York Millennium Yk M3 G4 Thru S6 S4 J2 Lb Se Sc J4 Users Manual 160.49 O2 (1296)

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OPERATING & MAINTENANCE

Supersedes: Nothing Form 160.49-O2 (1296)

MILLENNIUM

TM

CENTRIFUGAL LIQUID CHILLERS

MODEL YK M3 M3 G4 THRU YK S6 S4 J2 (STYLE C)

R-22 (COOLING ONLY)

MODEL YK LB LB G4 THRU YK SE SC J4 (STYLE C)

R-134a (COOLING ONLY)

WITH MICROCOMPUTER CONTROL CENTER

PART #371-01200-010, 371-01200-011 & 371-01200-015

FOR ELECTRO-MECHANICAL STARTER,

SOLID STATE STARTER & VARIABLE SPEED DRIVE

WW

WW

WARNINGARNING

ARNINGARNING

ARNING

SYSTEM CONTAINS REFRIGERANT UNDER PRESSURE.

SERIOUS INJURY COULD RESULT IF PROPER PROCEDURES ARE NOT

FOLLOWED WHEN SERVICING SYSTEM. ALL SERVICE WORK SHALL

BE PERFORMED BY A QUALIFIED SERVICE TECHNICIAN IN ACCOR-

DANCE WITH YORK INSTALLATION/OPERATION MANUAL.

27385A

2 YORK INTERNATIONAL

TT

TT

TABLE OF CONTENTSABLE OF CONTENTS

ABLE OF CONTENTSABLE OF CONTENTS

ABLE OF CONTENTS

SECTION 1 – Description of System and

Fundamentals of Operation ......................................... 4

SECTION 2 – MicroComputer Control Center ...................................... 6

SECTION 3 – System Operating Procedures..................................... 30

SECTION 4 – System Component Description .................................. 37

SECTION 5 – Operational Maintenance ............................................. 42

SECTION 6 – Trouble Shooting........................................................... 44

SECTION 7 – Maintenance ................................................................. 49

SECTION 8 – Preventive Maintenance............................................... 58

REFERENCE INSTRREFERENCE INSTR

REFERENCE INSTRREFERENCE INSTR

REFERENCE INSTRUCTIONSUCTIONS

UCTIONSUCTIONS

UCTIONS

DESCRIPTION FORM NO.

Solid State Starter – Operation & Maintenance 160.46-OM3.1

Variable Speed Drive – Operation 160.00-O1

Installation 160.49-N5

Installation and Operation of Printers 160.49-N7

Wiring Diagram – Unit with Electro-Mechanical Starter 160.49-PW7

Wiring Diagram – Field Connections (E-M Starter) 160.49-PW10

Wiring Diagram – Field Control Modifications 160.49-PW13

Wiring Diagram – Control Center with SS Starter 160.49-PW8

Wiring Diagram – Field Connections (SS Starter) 160.49-PW11

Wiring Diagram – Solid State Starter 160.49-PW14

Wiring Diagram – Unit with Solid State Starter 160.49-PW8

Wiring Diagram – Unit with Variable Speed Drive 160.49-PW9

Wiring Diagram – Field Connections (V.S.D.) 160.49-PW12

Wiring Diagram – Variable Speed Drive 160.49-PW15

Page

YORK INTERNATIONAL 3

FORM 160.49-O2

R-22 UNITS

YK N2 N1 H1 – CX C

DESIGN LEVEL (C)

POWER SUPPLY

– for 60 HZ

5 for 50 HZ

COMPRESSOR CODE

G4, H0, H1, H2, J1, J2

CONDENSER CODE

M3, M4, N3, N4, P3, P4, Q3, Q4, R3, R4, S3, S4

COOLER CODE

M3, M4, N3, N4, P3, P4, P5, P6, Q3, Q4, Q5, Q6,

R3, R4, R5, R6, S5, S6

MODEL

{MOTOR CODE:

60 HZ 50 HZ

CH CX 5CE 5CT

CJ CY 5CF 5CU

CK CZ 5CG 5CV

CL CA 5CH 5CW

CM CB 5CI 5CX

CN DA 5CJ 5DA

CP DB 5CK 5DB

CR DC 5CL 5DC

CS DD 5CM 5DD

CT DE 5CN 5DE

CU DF 5CO 5OF

CV DH 5CP 5OG

CW DJ 5CQ 5OH

5CR 5OJ

5CS

R-134a

YK NB PB H1 – CX C

DESIGN LEVEL (C)

POWER SUPPLY

– for 60 HZ

5 for 50 HZ

COMPRESSOR CODE

G4, H0, H1, H2, J1, J2, J3, J4

CONDENSER CODE

LB, LC, MB, MC, NB, NC,

PB, PC, QB, QC, RB, RC, SB, SC

COOLER CODE

LB, LC, MB, MC, NB, NC, PB, PC, PD, PE,

QB, QC, QD, QE, RB, RC, RD, RE, SD, SE

MODEL

{MOTOR CODE:

60 HZ 50 HZ

CH CX 5CE 5CT

CJ CY 5CF 5CU

CK CZ 5CG 5CV

CL CA 5CH 5CW

CM CB 5CI 5CX

CN DA 5CJ 5DA

CP DB 5CK 5DB

CR DC 5CL 5DC

CS DD 5CM 5DD

CT DE 5CN 5DE

CU DF 5CO 5DF

CV DH 5CP 5DG

CW DJ 5CQ 5DH

5CR 5OJ

5CS

NOMENCLATURE

4 YORK INTERNATIONAL

SECTION 1

DESCRIPTION OF SYSTEM AND FUNDAMENTALS OF OPERATION

FIG. 1 – MODEL YK MILLENNIUM CHILLER

SYSTEM OPERATION DESCRIPTION (See Fig. 2)

The YORK Model YK Millennium Chiller is commonly

applied to large air conditioning systems, but may be

used on other applications. The chiller consists of an

open motor mounted to a compressor (with integral

speed increasing gears) condenser, cooler and flow

control chamber.

The chiller is controlled by a modern state of the art

MicroComputer Control Center which monitors its op-

eration. The Control Center is programmed by the op-

erator to suit job specifications. Automatic timed start-

ups and shutdowns are also programmed to suit

nighttime, weekends, and holidays. The operating sta-

tus, temperatures, pressures, and other information per-

tinent to operation of the chiller are automatically dis-

played and read on a 40 character alphanumeric

message display. Other displays can be observed by

pressing the keys as labeled on the Control Center.

The chiller with the MicroComputer Control Center is

applied with an electro-mechanical starter, YORK Solid

State Starter (optional), or Variable Speed Drive (op-

tional).

In operation, a liquid (water or brine to be chilled) flows

through the cooler, where boiling refrigerant absorbs

heat from the water. The chilled liquid is then piped to

fan coil units or other air conditioning terminal units,

where it flows through finned coils, absorbing heat from

the air. The warmed liquid is then returned to the chiller

to complete the chilled liquid circuit.

The refrigerant vapor, which is produced by the boiling

action in the cooler, flows to the compressor where the

rotating impeller increases its pressure and tempera-

ture and discharges it into the condenser. Water flowing

through the condenser tubes absorbs heat from the re-

frigerant vapor, causing it to condense. The condenser

water is supplied to the chiller from an external source,

usually a cooling tower. The condensed refrigerant drains

from the condenser into the flow control chamber, where

the flow restrictor meters the flow of liquid refrigerant

to the cooler to complete the refrigerant circuit.

The major components of a chiller are selected to handle

the refrigerant which would be evaporated at full load

CONTROL

CENTER

COMPRESSOR

MOTOR

COOLER

27382A

DISCHARGE LINE PRE-ROTATION

VANE

ACTUATOR

CONDENSER

OIL RESERVOIR/

PUMP

27385A

YORK INTERNATIONAL 5

FORM 160.49-O2

7619A(D)

DETAIL A – COMPRESSOR PREROTATION VANES

design conditions. However, most systems will be called

upon to deliver full load capacity for only a relatively

small part of the time the unit is in operation.

CAPACITY CONTROL

The major components of a chiller are selected for full

load capacities, therefore capacity must be controlled to

maintain a constant chilled liquid temperature leaving

the cooler. Prerotation vanes (PRV), located at the en-

trance to the compressor impeller, compensate for varia-

tion in load (See Fig. 2. Detail A).

The position of these vanes is automatically controlled

through a lever arm attached to an electric motor lo-

cated outside the compressor housing. The automatic

adjustment of the vane position in effect provides the

performance of many different compressors to match

various load conditions from full load with vanes wide

open to minimum load with vanes completely closed.

FIG. 2 – REFRIGERANT FLOW-THRU CHILLER

PREROTATION VANES

(See Detail A)

SUCTION

COOLER

ELIMINATOR

OIL COOLER

LD00924

FLOW CONTROL

ORIFICE

SUB-COOLER

CONDENSER

DISCHARGE

BAFFLE

DISCHARGE

COMPRESSOR

6 YORK INTERNATIONAL

SECTION 2

MICROCOMPUTER CONTROL CENTER

LD00953

26879A

FIG. 3 – MICROCOMPUTER CONTROL CENTER AND KEYPAD

NOTE: This instruction covers operation of chillers equipped with Electro-Mechanical or Solid State Starters. If chiller

is equipped with Variable Speed Drive, Form 160.00-O1 is to be used in conjunction with this manual.

WARNING

This equipment generates, uses and can radiate radio frequency energy and if not installed and used in accor-

dance with the instructions manual, may cause interference to radio communications. Operation of this equip-

ment in a residential area is likely to cause interference in which case the user at his own expense will be

required to take whatever action may be required to correct the interference.

Additionally, any electronic equipment can generate EMI (electromagnetic interference) which, depending upon

the installation and magnitude, may affect other electronic equipment. The amount of EMI generated is deter-

mined by the source inductance, load inductance, and circuit impedances. Responsibility for assuring the

satisfactory operation of other equipment included in the same power source as the YORK equipment rests

solely with the user. YORK disclaims any liability resulting from any interference or for the correction thereof.

YORK INTERNATIONAL 7

FORM 160.49-O2

INTRODUCTION

The YORK MicroComputer Control Center is a micro-

processor based control system for R-22 or R134a cen-

trifugal chillers. It controls the leaving chilled water tem-

perature via pre-rotation vane control and has the ability

to limit motor current via control of the pre-rotation vanes.

Further, it is compatible with YORK Solid State Starter

(optional), Variable Speed Drive (optional), and electro-

mechanical starter applications.

A keypad mounted on the front of the Control Center

(see Fig. 3) allows the operator to display system oper-

ating parameters on a 40 character alphanumeric dis-

play that is part of the keypad. These readings are dis-

played via “Display” keypad as follows: (In the English

mode; temperatures in °F, pressures in (PSIG) (in the

metric mode, temperatures in °C, Pressures in KPa).

If unit is equipped with EPROM version C.02F(T).12 or

later, the Control Center can be equipped with an op-

tional Chinese language display, either as a field retrofit

or factory supplied option on new units. This display

mounts on the control center door, directly above the

standard display. Both the standard and Chinese dis-

play will be present, providing display messages simul-

taneously in both English and Chinese language.

The Control Center must be configured for Chinese dis-

play by a qualified service technician. Instructions are

contained in YORK service manual, Form 160.49-M3.

• CHILLED LIQUID TEMPERATURES – LEAVING AND

RETURN

• REFRIGERANT PRESSURES – EVAPORATOR AND

CONDENSER

• DIFFERENTIAL OIL PRESSURE

• CONDENSER LIQUID TEMPERATURES – OPTIONAL

FIELD INSTALLED – LEAVING AND RETURN

• OPTIONS

• PRINT *

• HISTORY PRINT *

• MOTOR CURRENT IN % OF FULL LOAD AMPS

• SATURATION TEMPERATURES – EVAPORATOR AND

CONDENSER

• DISCHARGE TEMPERATURE

• OIL TEMPERATURE

• HIGH & LOW OIL PRESSURE TRANSDUCER PRES-

SURE

• SOLID STATE STARTER MOTOR CURRENT / VOLTS

(When Supplied)

• CONDENSER REFRIGERANT LEVEL

The system setpoints (see Fig. 3) are operator entered

on the front control center Setpoints keypad. These

setpoints can also be displayed on the 40 character al-

phanumeric display. The system setpoints are:

• CHILLED LIQUID TEMPERATURE (LCWT)

• % CURRENT LIMIT

• PULLDOWN DEMAND LIMIT

• CLOCK (TIME-OF-DAY)

• DAILY SCHEDULE (7 DAY TIME-CLOCK PROGRAM-

MING)

• HOLIDAY

• REMOTE RESET TEMPERATURE RANGE

• DATA LOGGER

• CONDENSER REFRIGERANT LEVEL

The cause of all system shutdowns (safety or cycling) is

preserved (until the system is reset or restarts) in the

microcomputer’s memory for subsequent viewing on the

keypad display. The operator is continually advised of

system operating conditions by various background and

warning messages. The keypad contains special ser-

vice keys for use by the service technician when per-

forming system troubleshooting.

The MicroComputer Control Center is designed to be

compatible with most Energy Management Systems

(EMS) in use today. The standard design allows for the

following EMS interface:

1. Remote Start

2. Remote Stop

3. Remote LCWT Setpoint (Pulse Width Modulated sig-

nal)

4. Remote Current Limit Setpoint (Pulse Width Modulated

signal)

5. A “Remote Mode Ready to Start” Status Contacts

6. Safety Shutdown Status Contacts

7. Cycling Shutdown Status Contacts

As an enhancement to the standard EMS features, an

optional card file with plug-in printed circuit boards is

available. These optional cards will accept a remote

LCWT 0 to 10°F or 0 to 20°F setpoint offset and/or re-

mote current limit setpoint interface from three user in-

put choices.

1. 4-20mA

2. 0-10VDC

3. Contact Closures

* These keys provide a print-out when the customer connects a com-

patible printer to the Micro Board RS-232 serial port. (See Form

160.49-N7.)

8 YORK INTERNATIONAL

CONTROL CENTER

The Control Center front panel layout consists of five

key groups, one switch and a 1 line by 40 character al-

phanumeric vacuum fluorescent display: (see Fig. 3.)

CHARACTERISTIC DISPLAY – The alphanumeric

vacuum fluorescent display is located to the right of the

STATUS key. All messages, parameters, set points, and

data can be viewed at this location. The main communi-

cations between the operator or service technician and

the MicroComputer Control Center occurs on this dis-

play.

DISPLAY – Provide a direct readout of each monitored

parameter on the alphanumeric display.

ENTRY – These keys are used to enter the values for

the operator programmed setpoints. These keys are used

in conjunction with the Setpoint keys while in PRO-

GRAM mode.

SETPOINTS – These keys are used as follows:

1. To view each setpoint, in any mode, or

2. To select the individual setpoints that are programmed

by the operator in PROGRAM mode only.

Pressing the appropriate key enables the operator to

program that setpoint pressing the Entry keys.

SERVICE – Included in this group of keys are those func-

tions that are only relevant to servicing the chiller.

Typically, these keys would not be used for daily chiller

operation.

ACCESS CODE – Permits operator to access the pro-

gram.

PROGRAM – Permits operator to program the Control

Center.

MODE – Permits operator to check what mode the Con-

trol Center is presently in (LOCAL, REMOTE or SER-

VICE).

1. Service – allows manual PRV control with visual

display readout of PRV operation.

2. Local – allows manual compressor start from the

COMPRESSOR switch on the Control Center front.

3. Program – allows operator programming of system

setpoints.

4. Remote – allows remote start, remote stop of com-

pressor and remote reset of LCWT and % current

limit.

COMPRESSOR-START, RUN, STOP/RESET

SWITCH – This 3-position rocker switch is used to start

(except in REMOTE mode), stop/run/reset the system.

OPERATION

DISPLAYING SYSTEM PARAMETERS

The Display keys are used to display selected

monitored parameters as follows: (Refer to Fig. 3.)

• Press and release the appropriate Display key – the

message will be displayed for 2 seconds.

– or –

• Press and hold the appropriate Display key – the mes-

sage will be displayed and updated every 0.5 sec-

onds until the Display key is released.

– or –

• Press and release appropriate Display key, then press

and release the DISPLAY HOLD key – the message

will be displayed and updated every 2 seconds until

the DISPLAY HOLD key is again pressed and re-

leased, or 10 minutes have elapsed, whichever comes

first.

NOTE: If the display actually displays X’s, then the

monitored parameter is out of normal operat-

ing range (refer to Fig. 4). If the “English/Metric”

jumper is installed on the Micro Board, all tem-

peratures are displayed in degrees Fahrenheit

(°F) and all pressures are displayed in pounds

per sq. inch gauge (PSIG) except oil pressure

which is displayed in pounds per sq. inch differ-

ential (PSID). If the “English/Metric” jumper is

not installed, all temperatures are displayed in

degrees Centigrade (°C) and all pressures are

displayed in Kilo-Pascals (kPa).

YORK INTERNATIONAL 9

FORM 160.49-O2

To Display CHILLED LIQUID TEMPERATURES:

Press CHILLED LIQUID TEMPS display key as de-

scribed on page 7 to produce the following alphanu-

meric display message:

CHILLED LEAVING = XXX.X°F, RETURN = XXX.X°F

To Display REFRIGERANT PRESSURE:

Use REFRIGERANT PRESSURE display key as

described on page 7 to produce the following alpha-

numeric display message:

EVAP = XXX.X PSIG; COND = XXX.X PSIG

To Display OIL PRESSURE:

Use OIL PRESSURE display key as described on

page 7 to produce the following alphanumeric dis-

play message:

OIL PRESSURE = XXXX.X PSID

The differential pressure displayed is the pressure dif-

ference between the high side oil pressure transducer

(output of oil filter) and the low side oil pressure trans-

ducer (compressor housing). Displayed value includes

offset pressure derived from auto-zeroing during

“START SEQUENCE INITIATED”. If either transducer

is out-of-range, XX.X is displayed. Oil pressure is

calculated as follows:

______ PSID = (HOP – LP) – OFFSET PRESSURE

OFFSET PRESSURE: Pressure differential between

the HOP transducer and LOP transducer outputs dur-

ing a 3 second period beginning 10 seconds after the

start of “START SEQUENCE INITIATED”. During this

time, the transducers will be sensing the same pres-

sure and their outputs should indicate the same pres-

sure. However, due to accuracy tolerances in trans-

ducer design, differences can exist. Therefore, to com-

pensate for differences between transducers and as-

sure differential pressure sensing accuracy, the OFF-

SET PRESSURE is subtracted algebraically from the

differential pressure. The offset pressure calculation

will not be performed if either transducer is out-of-range.

The offset value will be taken as 0 PSI in this instance.

To Display OPTIONS:

This key is not used.

NO OPTIONS INSTALLED

is displayed when this key is pressed.

To Display SSS MOTOR CURRENT / VOLTS:

(Solid State Starter Applications Only)

If chiller is equipped with a YORK Solid State Starter,

use SSS MOTOR CURRENT / VOLTS key to dis-

play 3-phase compressor motor current and 3-phase

Solid State Starter input line voltage.

Continuously pressing this key will display the mo-

tor current and line voltage alternately. When used

with the DISPLAY HOLD key, motor current and

line voltage will alternately be displayed each time

this key is pressed. The messages are as follows:

A AMPS = XXXX; B AMPS = XXXX; C AMPS = XXXX

V A-B = XXXX; V B-C = XXXX; V C-A = XXXX

If chiller is not equipped with a Solid State Starter,

this key produces the following message:

SOLID STATE STARTER NOT INSTALLED

In PROGRAM mode, this key is used to display the

applicable line voltage range (200-208VAC, 220-

240VAC, 380VAC, 400VAC, 415VAC, 440-480VAC,

500-600VAC, Supply Voltage Range Disabled). The

correct line voltage range is programmed at the

YORK factory and is checked by the service tech-

nician at start-up. For security reasons, a special

access code is required to program the line volt-

age range. The line voltage range is used to deter-

mine a low line voltage threshold for cycling shut-

down. Refer to “System Setpoints” for Trip/Reset

values.

DISPLAY

READS

CONDENSER PRESS. = < 6.8 PSIG, or > 300 PSIG XX.X PSIG

EVAPORATOR PRESS. = < 50 PSIG, or > 125 PSIG XX.X PSIG

EVAP. PRESS. (BRINE) = < 25 PSIG, or > 100 PSIG XX.X PSIG

HOP TRANSDUCER = < 59.1 PSIG, or > 314.9 PSIG XX.X PSIG

LOP TRANSDUCER = < 23.2 PSIG, or > 271.8 PSIG XX.X PSIG

DISCHARGE TEMP. = < 20.3°F; > 226.4°F XXX.X°F

OIL TEMP. = < 20.3°F; > 226.4°F XXX.X°F

LEAVING CONDENSER

WATER TEMP. = < 8.4°F; > 134.1°F XXX.X°F

ENTERING CONDENSER

WATER TEMP. = < 8.4°F; > 134.1°F XXX.X°F

LEAVING EVAPORATOR = < 0°F XX.X°F

WATER TEMP. = > 81.1°F XX.X°F

ENTERING EVAPORATOR = < .1°F XX.X°F

WATER TEMP. = > 93°F XX.X°F

FIG. 4 – SYSTEM PARAMETERS – OUT OF

RANGE READINGS

10 YORK INTERNATIONAL

To Display CONDENSER LIQUID TEMPERATURES

(Field Installed Option Package):

Use CONDENSER LIQUID TEMPS display key as

described above to produce the following alphanu-

meric display message:

COND LEAVING = XXX.X°F; RETURN = XXX.X°F

NOTE: If the condenser liquid thermistors are not con-

nected, or both thermistors are “out of range”,

the display will blank when this key is pressed.

To Initiate a PRINT to Printer:

Press the PRINT key to initiate a printout to an op-

tional printer. When the key is pressed,

PRINT ENABLE

is displayed.

Refer to “MicroComputer Control Center – System

Status Printers” instruction, Form 160.49-N7 for de-

tails of the optional printers.

To Display MOTOR CURRENT:

Press the % MOTOR CURRENT display key as

described above to display motor current as a per-

cent of Full Load Amps (FLA). The message is as

follows:

MOTOR CURRENT = XXX% FLA

NOTE: • Liquid-Cooled Solid State Starter Applications

– the % Motor Current displayed is the highest

of three line currents divided by the programmed

chiller FLA value x 100%.

• Electro-Mechanical Starter Applications – the

% Motor Current displayed is the highest of the

three line currents.

To Display OPERATING HOURS and STARTS

COUNTER:

Use the OPERATING HOURS key as described on

page 8, to produce the following message:

OPER. HOURS = XXXXX; START COUNTER = XXXXX

NOTE: The operating hours and starts counter can be

reset to zero. Refer to “Programming the Micro-

Computer Control Center”, page 14. However,

the purpose of the OPERATING HOURS key

is to display the total accumulated chiller run

time. Therefore, the operating hours should not

be arbitrarily reset.

SYSTEM SETPOINTS

The system setpoints may be programmed by the sys-

tem operator. The Setpoints keys are located on the

Control Center keypad (see Fig. 3). To program, see “Pro-

gramming System Setpoints”, page 14. The following

is a description of these setpoints (with the English/

Metric jumper installed on the Micro Board):

CHILLED LIQUID TEMP – This key displays the leav-

ing chilled water temperature (LCWT) setpoint in degrees

Fahrenheit. If not programmed, the default value is 45°F.

See “Programming System Setpoints”, page 15).

NOTE: If an Energy Management System is interfaced

to the Control Center for the purpose of remote

LCWT setpoint reset, then the operator-pro-

grammed chilled liquid temperature will be the

base or lowest setpoint available to the Energy

Management System (EMS). This chilled liquid

temperature value must also be entered into the

EMS. Further, any subsequent change to this

value must also be entered into the EMS.

% CURRENT LIMIT – This key displays the maximum

value of motor current permitted by its programmed set-

ting. The value is in terms of percent of Full Load Amps

(FLA). If not programmed, the default value is 100%. (See

“Programming System Setpoints”, page 15.)

If chiller is equipped with a YORK Solid State Starter,

the system FLA is also displayed. This value is pro-

grammed by the factory and should never be changed.

The Micro Board uses this value to calculate and dis-

play the % motor current parameter that is displayed

when the % MOTOR CURRENT display key is pressed.

Also, proper current limit control depends on the cor-

rectly programmed FLA value. For security reasons, a

special access code is required to program the FLA value.

It should only be changed by a service technician.

PULL DOWN DEMAND – This function is used to pro-

vide energy savings following the chiller start-up. This

key displays a programmable motor current limit and a

programmable period of time. Operation is as follows:

Whenever the system starts, the Pull Down Demand

Limit is maintained for the programmed time, then the

current limit control returns to % current limit setpoint.

The maximum permitted motor current is in terms of %

FLA. The duration of time that the current is limited is in

YORK INTERNATIONAL 11

FORM 160.49-O2

terms of minutes (to a maximum of 255). If not pro-

grammed, the default value is 100% FLA for 00 min-

utes. (See “Programming Systems Setpoints”, page 16.)

Thus, no pull down demand limit is imposed following

system start, and the % current limit setpoint is used.

CLOCK – This key displays the day of the week, time of

day and calendar date. If not programmed, the default

value is

SUNDAY 12:00 AM 1/1/92 .

(See “Programming System Setpoints”, page 16.)

DAILY SCHEDULE – This key displays the programmed

daily start and stop times, from Sunday thru Saturday

plus Holiday. If desired, the Control Center can be pro-

grammed to automatically start and stop the chiller as

desired. This schedule will repeat on a 7-day calendar

basis. If the Daily Schedule is not programmed, the de-

fault value is 00:00 AM start and stop times for all days

of the week and the holiday. (Note that the system will

not automatically start and stop on a daily basis with

these default values because 00:00 is an “Impossible”

time for the Micro Board. See “Programming System

Setpoints”, page 17.) Finally, one or more days in the

week can be designated as a holiday (see description

under HOLIDAY setpoint) and the Control Center can

be programmed (usually Daily Schedule setpoint) to

automatically start and stop the chiller on those days so

designated. The operator can override the time clock

at any time using the COMPRESSOR switch.

Note that if only a start time is entered for a particular

day, the compressor will not automatically stop until a

scheduled stop time is encountered on a subsequent

day.

HOLIDAY – This key indicates which days in the upcom-

ing week are holidays. On those designated days, the

chiller will automatically start and stop via the holiday

start and stop times programmed in the DAILY SCHED-

ULE setpoint. It will do this one time only and the follow-

ing week will revert to the normal daily schedule for that

day.

REMOTE / RESET TEMP RANGE – This key displays

the maximum offset of remote LCWT setpoint reset. This

offset is either 10° or 20°F as programmed. When in the

REMOTE mode, this value is added to the operator pro-

grammed CHILLED LIQUID TEMP setpoint and the sum

equals the temperature range in which the LCWT can

be reset. For example, if the operator programmed

CHILLED LIQUID TEMP setpoint is programmed with a

value of 10°F, then the CHILLED LIQUID TEMP setpoint

can be remotely reset over a range of 46°F to 56°F (46

+ 10 = 56). If not programmed, the default value for this

parameter is 20°F.

For additional information on remote LCWT reset, refer

to Form 160.49-PW13.

NOTE: If an Energy Management System is interfaced

to the Control Center for the purpose of remote

LCWT setpoint reset, then the operator pro-

grammed REMOTE RESET TEMP RANGE

value determines the maximum value of tem-

perature reset controlled by the Energy Man-

agement System.

DATE LOGGER – This key is used when an optional

printer is connected to the MicroComputer Control Cen-

ter. Refer to Form 160.49-N7 for operation instructions.

SSS MOTOR CURRENT/VOLTS – This key is used on

Solid State Starter applications only. Although this is a

display key, it is used to program the applicable AC

power line voltage range (380VAC, 400VAC, 415VAC,

440-480VAC, 550-600VAC). The MicroComputer Con-

trol Center uses this entry to determine the under-volt-

age and overvoltage shutdown threshold. For each

line voltage category, there is an undervoltage and ov-

ervoltage shutdown threshold. If the AC power line volt-

age exceeds these thresholds for 20 continuous sec-

onds, the chiller shuts down and displays

MON 10:00 AM LOW LINE VOLTAGE

– or –

MON 10:00 AM HIGH LINE VOLTAGE

This overvoltage and undervoltage protection can be

disabled. Refer to chart below:

For security reasons, a special access code is required

to program the supply voltage range. The supply voltage

range is programmed at the factory and should only be

changed by a service technician.

LOW / HIGH LINE VOLTAGE TRIP / RESET VALUES

COMPRESSOR LOW LINE VOLTAGE HIGH LINE VOLTAGE

MOTOR OPERATING POINT OPERATING POINT

SUPPLY VOLTAGE CUTOUT-(V) CUTIN-(V) CUTOUT-(V) CUTIN-(V)

RANGE – (V) (ON FALL) (ON RISE) (ON RISE) (ON FALL)

380 305 331 415 414

400 320 349 436 435

415 335 362 454 453

440-480 370 400 524 523

550-600 460 502 655 654

Supply Voltage NONE 0 NONE 0

Range Disabled

12 YORK INTERNATIONAL

DISPLAYING SYSTEM SETPOINTS

The currently programmed Setpoint values can be

viewed at any time (see page 22) in SERVICE, LOCAL

or REMOTE operating mode as follows:

• Press and release the appropriate Setpoint key – the

message will be displayed for 2 seconds.

– or –

• Press and hold the appropriate Setpoint key – the

message will be displayed as long as the key is

pressed.

– or –

• Press and release the appropriate Setpoint key, then

press and release the DISPLAY HOLD key. The mes-

sage will be displayed until the DISPLAY HOLD key is

again pressed and released, or 10 minutes have

elapsed, whichever comes first.

To Display CHILLED LIQUID TEMP Setpoint:

Use CHILLED LIQUID TEMP setpoint key as de-

scribed on page 10 to produce the following mes-

sage:

LEAVING SETPOINT = XX.X °F

NOTE: The value displayed is the actual LCWT setpoint.

For example, the value displayed in LOCAL

or

PROGRAM modes is that which is operator pro-

grammed. The value displayed in the REMOTE

mode is that base setpoint with added tempera-

ture reset by an Energy Management System,

via remote LCWT setpoint (PWM signal) if a re-

mote reset signal was received within 30 min-

utes.

To Display % CURRENT LIMIT Setpoint:

Use % CURRENT LIMIT setpoint key as described

above to produce the following message:

CURRENT LIMIT = XXX % FLA

NOTE: The value displayed is the actual % current limit

setpoint. For example, the value displayed in

LOCAL or PROGRAM mode is that which is

operator programmed. The value displayed in

the REMOTE mode is that which has been pro-

grammed by the Energy Management System

via the remote current limit setpoint input.

If chiller is equipped with a YORK Solid State Starter,

the message is:

CURRENT LIMIT = XXX % FLA; *MTR CUR = 000 FLA

NOTE: On Solid State Starter applications, this value is

programmed at the YORK factory. A special ac-

cess code is required.

To Display PULL DOWN DEMAND Setpoint:

Use PULL DOWN DEMAND setpoint key as de-

scribed on page 10 to produce the following mes-

sage:

SETPOINT = XXX MIN @ XX % FLA XXX MIN LEFT

To Display CLOCK Setpoint (Time of Day):

Use CLOCK setpoint key as described above to

produce the following message:

TODAY IS DAY XX:XX AM/PM 1/1/92

To Display DAILY SCHEDULE Setpoints:

• Press and hold the DAILY SCHEDULE setpoint key.

The chiller start and stop times for each day of the

week are sequentially displayed, beginning with Sun-

day and ending with Holiday. The display will continu-

ously scroll until the DAILY SCHEDULE key is re-

leased. – or –

• Press and release the DAILY SCHEDULE setpoint key.

Then press and release the DISPLAY HOLD key. The

chiller start and stop times for each day of the week

are sequentially displayed beginning with Sunday and

ending with Holiday. The display will continuously scroll

until the DISPLAY HOLD key is again pressed and

released, or 10 minutes have elapsed, whichever

comes first.

The display message for DAILY SCHEDULE will scroll

in the following sequence:

SUN START = 08:30 AM STOP = 06:00 PM

MON START = 05:00 AM STOP = 07:00 PM

YORK INTERNATIONAL 13

FORM 160.49-O2

TUE START = 05:00 AM STOP = 07:00 PM

WED START = 05:00 AM STOP = 07:00 PM

THU START = 05:00 AM STOP = 07:00 PM

FRI START = 05:00 AM STOP = 07:00 PM

SAT START = 05:00 AM STOP = 01:00 PM

HOL START = 00:00 AM STOP = 00:00 PM

To Display HOLIDAY Setpoints:

Use HOLIDAY setpoint key as described in the be-

ginning of this section to produce the following mes-

sage:

S_ M_ T_ W_ T_ F_ S_ HOLIDAY NOTED BY *

NOTE: On the days that are designated by an *, the

chiller will automatically start and stop per the

holiday schedule established in DAILY SCHED-

ULE setpoints.

To Display REMOTE RESET TEMP RANGE Setpoint:

Use REMOTE RESET TEMP RANGE setpoint key

as described above to produce the following mes-

sage:

REMOTE RESET TEMP RANGE = 10°F

– or –

REMOTE RESET TEMP RANGE = 20°F

To Display DATA LOGGER setpoints:

Refer to YORK, Form 160.49-N7 for operation of this

key.

To Display UNDERVOLTAGE setpoints:

(Solid State Starter Applications Only)

Press SSS MOTOR CURRENT/VOLTS key in PRO-

GRAM mode to display the selected voltage range.

One of the following messages will be displayed.

SUPPLY VOLTAGE RANGE 380

– or –

SUPPLY VOLTAGE RANGE 400

– or –

SUPPLY VOLTAGE RANGE 415

– or –

SUPPLY VOLTAGE RANGE 440-480

– or –

SUPPLY VOLTAGE RANGE 550-600

– or –

SUPPLY VOLTAGE RANGE DISABLED

A special access code is required to program the Sup-

ply Voltage Range. The Supply Voltage Range is pro-

grammed at the factory and checked at system start-up.

(Note to service technician: Refer to programming in-

structions in Service Instruction, Form 160.49-M3.)

14 YORK INTERNATIONAL

PROGRAMMING

THE MICROCOMPUTER CONTROL CENTER

FIG. 5 – KEYPAD – PROGRAMMING SYSTEM

SETPOINTS

PROGRAMMING SYSTEM SETPOINTS

The system setpoints can be entered at any time . . . . .

even when the system is running. Proceed as follows to

enter system setpoints. (Refer to Fig. 5.)

1. Press ACCESS CODE key.

2.

ENTER VALID ACCESS CODE _ _ _ _

is displayed.

3. Using ENTRY keys, enter 9 6 7 5.

4. As each digit is entered, the characters Y O R K are

displayed.

NOTE: If digits other than 9 6 7 5 are entered,

YORKis still displayed.

NOTE: For ease in remembering the code, note that

the letters YORKcorrespond to the dig-

its 9675on a telephone dial

.

5. Press ENTER key.

NOTE: If digits other than 9675 were entered in step

No. 4,

INVALID ACCESS CODE

is displayed

when the ENTER key is pressed. If this oc-

curs, enter the correct access code (9675)

and proceed.

6.

ACCESS TO PROGRAM KEY AUTHORIZED

is displayed.

NOTE: Unless terminated by pressing the ACCESS

CODE key again, the operator will have ac-

cess to the PROGRAM key for 10 minutes.

When 10 minutes have elapsed, access to

PROGRAM key will be automatically disabled

and the operator must return to step No. 1 to

gain access.

7. Press PROGRAM key.

8.

PROGRAM MODE, SELECT SETPOINT

is displayed.

9. Enter setpoints as detailed below. If you make a mis-

take when entering a value, press CANCEL key and

then ENTER key. The display will revert to the default

values and the cursor will return to the first change-

able digit. You can then proceed to enter the correct

values. If the entered value exceeds acceptable lim-

its,

OUT OF RANGE – TRY AGAIN!

message will be displayed for 2 seconds, then the

PROGRAM MODE, SELECT SETPOINT

message will re-

appear.

10.When all the desired setpoints have been entered,

press the ACCESS CODE key to exit PROGRAM

mode and terminate access to PROGRAM mode.

ACCESS TO PROGRAM MODE DISABLED

is displayed.

The Control Center will automatically return to LO-

CAL, REMOTE or SERVICE mode . . . . whichever

was last selected.

LD00954

YORK INTERNATIONAL 15

FORM 160.49-O2

To enter CHILLED LIQUID TEMP Setpoint: (Refer to

Fig. 6.)

1. Press and release CHILLED LIQUID TEMP setpoint

key. The following program prompt message will be

displayed:

LEAVING SETPOINT = XX.X °F (BASE)

(BASE) refers to the base or lowest setpoint avail-

able to an Energy Management System. If any En-

ergy Management System is applied, this value must

be entered into the Energy Management System.

Refer to previous explanation or REMOTE/RESET

TEMP RANGE, page 11.

2. Use ENTRY keys to enter desired value.

3. Press and release ENTER key.

PROGRAM MODE, SELECT SETPOINT

message is displayed.

FIG. 6 – KEYPAD – PROGRAMMING “LEAVING

CHILLED WATER TEMP” SETPOINT

To Enter % CURRENT LIMIT Setpoint:

(Electro-Mechanical Starter, refer to Fig. 7)

1. Press and release % CURRENT LIMIT setpoint key.

The following program prompt message is displayed:

CURRENT LIMIT = XXX% FLA

2. Use ENTRY keys to enter desired value.

3. Press and release ENTER key.

PROGRAM MODE, SELECT SETPOINT

message is displayed.

(Solid State Starter, refer to Fig. 7)

1. Press and release % CURRENT LIMIT setpoint key.

The following program prompt message is displayed:

CURRENT LIMIT = XXX% FLA; MTR CUR = _ _ _ FLA

2. Use ENTRY keys to enter desired value.

NOTE: Motor Current FLA value is entered by YORK

factory and checked at system start-up. It

cannot be changed without special access

code. (Note to service technician: refer to

“Programming Instructions” in Service in-

struction, Form 160.49-M3.

3. Press and release ENTER key.

PROGRAM MODE, SELECT SETPOINT

message is displayed.

FIG. 7 – KEYPAD – PROGRAMMING “% CURRENT

LIMIT” SETPOINT

LD00955

LD00956

16 YORK INTERNATIONAL

To Enter PULL DOWN DEMAND Setpoint:

(Refer to Fig. 8.)

1. Press and release PULL DOWN DEMAND setpoint

key. The following program prompt message is dis-

played:

SETPOINT = XXX MIN @ XXX % FLA, XXX MIN LEFT

2. Use Entry keys to enter desired values. For expla-

nation, see PULL DOWN DEMAND, page 12. Note

that “XX min left” is not an operator entered value.

3. Press and release ENTER key.

PROGRAM MODE, SELECT SETPOINT

message is displayed.

FIG. 8 – KEYPAD – PROGRAMMING “PULL DOWN

DEMAND” SETPOINT

To Enter CLOCK Setpoint: (Refer to Fig. 9.)

1. Assure Micro Board Program jumper J57 is in

“CLKON” position.

2. Press and release CLOCK setpoint key. The follow-

ing program prompt message is displayed:

TODAY IS MON 10:30 PM 1/1/92

3. Press ADVANCE DAY / SCROLL key until the pro-

gram per day of week appears on the display.

4. Use Entry keys to enter proper time of day.

5. Press AM/PM key to change the AM to PM or vice

versa.

6. Use Entry keys to enter proper calendar date,

(MONTH/DAY/YR). If month and day are single digit

entries, precede the entry with “0”. For example,

02/04/88.

7. Press and release ENTER key.

PROGRAM MODE, SELECT SETPOINT

message is displayed.

FIG. 9 – KEYPAD – PROGRAMMING “CLOCK”

SETPOINT

LD00957

LD00958

YORK INTERNATIONAL 17

FORM 160.49-O2

To Enter DAILY SCHEDULE Setpoint:

(Refer to Fig. 10.)

1. Press and release DAILY SCHEDULE setpoint key.

The following prompt message is displayed:

SUN START = XX:XX AM, STOP = XX:XX AM

2. If the displayed start and stop time is not the desired

schedule, enter the desired start and stop times as

follows:

a. If you do not want the chiller to automatically start

and stop on this day, press CANCEL key.

b. Use the Entry keys to enter desired hours and

minutes start time.

c. If necessary, press the AM/PM key to change “AM”

to “PM” or vice versa.

d. Use the Entry keys to enter desired hours and

minutes stop time.

e. If necessary, press the AM/PM key to change “AM”

to “PM” or vice versa.

3. Press and release ADVANCE DAY/SCROLL key. The

following prompt message is displayed:

MON START = XX:XX AM, STOP = XX:XX AM

4. Enter the desired start and stop time per Step 2.

5. Press and release ADVANCE DAY/SCROLL key. The

following prompt message is displayed:

REPEAT MON SCHEDULE MON-FRI? YES = 1; NO = 0

a. If you press the 1 Entry key, Monday’s start and

stop time will be automatically entered for Tues-

day through Friday.

– or –

b. If you press the 0 Entry key, Tuesday through Fri-

day can be programmed with different start and

stop times.

6. Use the ADVANCE DAY / SCROLL key with proce-

dure in Step 2. To enter start and stop times for

remainder of the week plus a holiday schedule if

required.

7. Press the ENTER key.

PROGRAM MODE, SELECT SETPOINT

is displayed.

FIG. 10 – KEYPAD – PROGRAMMING “DAILY

SCHEDULE” SETPOINT

LD00959

18 YORK INTERNATIONAL

To Enter HOLIDAY Setpoint: (Refer to Fig. 11.)

1. Press and release HOLIDAY setpoint key. The fol-

lowing program prompt message is displayed:

S_ M_ T_ W_ T_ F_ S_ HOLIDAY NOTED BY

r

2. Press and release ADVANCE DAY/SCROLL key to

move cursor to the day that you wish to designate as

a holiday.

3. Press and release r entry key. An r will appear

next to the selected day.

4. After you have placed an r next to each of the days

that you wish to designate a holiday, press ENTER

key

PROGRAM MODE, SELECT SETPOINT

message is displayed.

To cancel all of the designated holidays: perform Step

1, press CANCEL key, and then press ENTER key.

PROGRAM MODE, SELECT SETPOINT

message is displayed.

To cancel one of the designated holidays: perform

Step 1, press ADVANCE DAY / SCROLL key until

the cursor appears to the right of the desired day,

press the

r key, then press the ENTER key.

FIG. 11 – KEYPAD – PROGRAMMING “HOLIDAY”

SETPOINT

To Enter REMOTE/ RESET TEMP RANGE Setpoint:

(Refer to Fig. 12.)

1. Press and release REMOTE/RESET TEMP RANGE

setpoint key. The following program prompt message

is displayed:

REMOTE TEMP SETPOINT RANGE = XX °F

2. Use Entry keys desired value (10 or 20).

3. Press and release ENTER key.

PROGRAM MODE, SELECT SETPOINT

message is displayed.

To Enter DATA LOGGER Setpoint:

Refer to Form 160.49-N7 for operation of this key.

FIG. 12 – KEYPAD – PROGRAMMING “REMOTE

RESET” TEMP RANGE

LD00961

LD00962

YORK INTERNATIONAL 19

FORM 160.49-O2

FIG. 13 – KEYPAD – SERVICE KEYS LOCATION

The Service keys are provided for the service techni-

cian’s use when performing routine maintenance or when

troubleshooting the system. The WARNING RESET and

PRE-ROTATION VANES keys are enabled in SERVICE

mode only. The remainder of the Service keys are en-

abled in SERVICE, LOCAL or REMOTE mode.

PRE-ROTATION VANES KEYS

If chiller is equipped with the REFRIGERANT LEVEL

CONTROL (and EPROM version C.02F(T).13 or later),

the pre-rotation vanes keys can be used to manually

control the refrigerant level variable orifice or the pre-

rotation vanes. The procedure to select either manual

vane or manual variable orifice control is contained in

“Special Setpoints and Programming Procedures” sec-

tion of Service manual, Form 160.49-M3 and must be

performed by a qualified service technician only.

OPEN – Press and release this key to drive the pre-

rotation vanes open. If the chiller is running,

SYSTEM RUN – VANES OPENING

is displayed. If chiller is

not running,

SYS READY TO START – VANES OPENING

is

displayed. The vanes will continue to open until the

CLOSE, HOLD, or AUTO (if temperature error requires

it) keys are pressed and released.

HOLD – Press and release this key to hold the pre-

rotation vanes in their present position. If the chiller is

running,

SYSTEM RUN – VANES HOLDING

is displayed.

If chiller is not running,

SYS READY TO START – VANES HOLDING

is displayed. The

vanes will remain stationary until the OPEN, HOLD, or

AUTO keys are pressed and released.

AUTO – Press and release this key to put the pre-rota-

tion vanes under LCWT control as long as the current

limit setpoint is not reached, which causes the current

limit function to override the LCWT control. If system is

running,

SYSTEM RUN – AUTO VANES

is displayed. The

actual opening and closing of the vanes is indicated on

the display. When the vanes are opening,

SYSTEM RUN – VANES OPENING

is displayed. If the vanes

are closing,

SYSTEM RUN – VANES CLOSING

is displayed.

Whenever the Control Center is in LOCAL, REMOTE or

PROGRAM mode, the vane control circuitry is automati-

cally placed in AUTO mode and the vanes operate to

control the leaving chilled water temperature to the pro-

grammed setpoint.

CLOSE – Press and release this key to drive the pre-

rotation vanes closed. If the chiller is running,

SYSTEM RUN – VANES CLOSING

is displayed. If chiller is

not running,

SYS READY TO START – VANES CLOSING

is

displayed. When the vanes are full closed,

SYS READY TO START – VANES CLOSED

is displayed. The

vanes will continue to close until the OPEN, HOLD, or

AUTO keys are pressed.

SERVICE KEYS

LD00963

20 YORK INTERNATIONAL

OTHER SERVICE KEYS

WARNING RESET – Press and release this key to re-

set any “WARNING” or “STATUS” message that can be

reset with this key, unless the condition still exists. To

reset any cycling or warning message, place the Con-

trol Center in SERVICE mode and press WARNING

RESET key. To reset any safety shutdown message,

press WARNING RESET key in SERVICE mode with

the COMPRESSOR switch in the STOP/RESET posi-

tion.

MANUAL OIL PUMP – This key is operational in any

mode. Press and release this key to run the oil pump.

Press and release the key again to stop the oil pump. A

10-minute maximum is imposed on the running of the oil

pump (i.e., the oil pump will automatically shut off after

10 minutes). If a longer running time is desired, the key

must be pressed again. The manual oil pump feature is

disabled during “START SEQUENCE INITIALIZED” to

allow for auto-zeroing of oil pressure transducers.

DISPLAY DATA – This key is operational in any three

of the Control Center modes of operation (SERVICE,

LOCAL or REMOTE). It is used to display certain sys-

tem operating parameters that are relevant to trouble-

shooting the chiller system.

Press and the DISPLAY DATA key. The following mes-

sages will sequentially scroll on the display. Each mes-

sage will be displayed for 2 seconds.

Messages 1 and 2 are only displayed if unit is equipped

with EPROM version C.02F(T).13 or later and Refriger-

ant Level Control has been enabled by a qualified ser-

vice technician using the “Special Setpoints and Pro-

gramming” procedures section of Service manual, Form

160.49-M3.

NO. 1

MANUAL VANE OPERATION ALLOWED

– Displayed when the

PRE-ROTATION VANES service keys have been se-

lected for manual VANE control. This allows these keys

to manually control the vanes in Service mode. The pro-

cedure to select manual vanes control is in Service

manual, Form 160.49-M3 and should be performed only

by a qualified service technician.

– or –

NO. 1

MANUAL LEVEL CONTROL ALLOWED

– Displayed when the

PRE-ROTATION VANES keys have been selected for

manual REFRIGERANT LEVEL control. This allows

these keys to manually control the refrigerant level con-

trol variable orifice in Service mode. When manual re-

frigerant level control is selected, the pre-rotation vanes

Service keys cannot be used to control the vanes. The

procedure to select manual refrigerant level control is in

Service manual, Form 160.49-M3 and should be per-

formed only by a qualified service technician.

NO. 2

PULLDN LEVEL = XXX%; SETP = XXX%; ACTUAL = XXX%

– Displayed when there is a refrigerant level setpoint

pulldown (ramp) in effect. PULLDN LEVEL is the refrig-

erant level setpoint that is presently in effect. SETP is

the refrigerant level setpoint that has been programmed

by the service technician and ACTUAL is the refrigerant

level in the condenser. The pulldown period is 15 min-

utes in duration. During the pulldown period, a linearly

increasing ramp is applied to the level setpoint. This

causes the setpoint to increase from 0% to the pro-

grammed value over a period of 15 minutes. After the 15

minutes have elapsed, the setpoint remains the pro-

grammed value and this message is replaced by the

message

ACTUAL = XXX%; LEVEL SETP = XXX%

as

described below.

A refrigerant level setpoint pulldown is put into effect when

the vanes are driven from a fully closed to an open posi-

tion, if the actual refrigerant level is less than the level

setpoint when the vane motor end switch (VMS) opens.

If the actual level is greater than the setpoint when the

VMS opens, the level is controlled to the programmed

setpoint. Whenever the vanes go to the fully closed po-

sition (VMS closed), any pulldown that is in effect is can-

celled.

– or –

NO. 2

ACTUAL LEVEL = XXX%; LEVEL SETP = XXX%

– Displays

the actual refrigerant level in the condenser and the re-

frigerant level setpoint programmed by the service tech-

nician. This message replaces the previous message

after a refrigerant level setpoint pulldown period termi-

nates.

NO. 3

SAT TEMPS EVAP = XX.X°F; COND = XX.X°F

– This is the

refrigerant saturation temperatures for the evaporator and

condenser.

NO. 4

DISCHARGE TEMP = XXX.X°F; OIL TEMP = XXX.X°F

NO. 5

HOP = XX.X PSIG; LOP = XX.X PSIG

– This is the low oil

pressure (LOP) as measured at the oil sump and the

high oil pressure (HOP) as measured at the compres-

sor bearing input.

YORK INTERNATIONAL 21

FORM 160.49-O2

NO. 6

ACTUAL POS = XX MILS; REF = YY MILS

– ACTUAL POS is

the distance between the high speed thrust collar and

the proximity probe that is used to measure the position.

REF is the reference position established at time of com-

pressor manufacture.

NO. 7

HIGH SPEED DRAIN TEMP = XXX.X °F

– Temperature of oil

in high speed drain line.

To hold any of the above messages, press the DISPLAY

DATA key, then press the DISPLAY HOLD key. The

message will be displayed and updated every 2 sec-

onds until the DISPLAY DATA key is pressed again,

whereupon the next message is displayed. To return to

the normal foreground messages, press the DISPLAY

HOLD key.

HISTORY PRINT – This key is used to initiate a history

print to the optional printer. Refer to Form 160.49-N7 for

operation of this key.

OPERATING MODES

The MicroComputer Control Center can be operated in

four different operating modes as follows:

SERVICE – enables all the Service keys except DIS-

PLAY DATA, MANUAL OIL PUMP, and HISTORY

PRINT, which are enabled in all modes. See “Service

Keys”, page 20.

LOCAL – This is the normal operating mode. The com-

pressor can be started and stopped from the Control

Center. Also, the Display and Setpoints parameters can

be displayed.

PROGRAM – Allows the operator to program the Set-

points parameters, and change operating modes.

REMOTE – In this mode, the Control Center will ac-

cept control signals from a remote device (i.e., Energy

Management System) or cycling input. The control sig-

nal inputs are:

1. Remote Start

2. Remote Stop

3. Remote LCWT Setpoint

4. Remove Current Limit Setpoint

NOTE: The compressor can be stopped by the COM-

PRESSOR switch, regardless of the operating

mode. The switch must be in RUN position to

enable REMOTE mode. The operator cannot

locally start the compressor using the COM-

PRESSOR switch when in the REMOTE mode.

To determine which operating mode the Control Center

is presently in, simply press the MODE key.

• If the Control Center is in LOCAL mode,

LOCAL OPERATING MODE IN EFFECT

is displayed.

• If the Control Center is in REMOTE mode,

REMOTE OPERATING MODE IN EFFECT

is displayed.

• If the Control Center is in SERVICE mode,

SERVICE OPERATING MODE IN EFFECT

is displayed.

To change operating mode, proceed as follows:

1. Press ACCESS CODE key.

2.

ENTER VALID ACCESS CODE _ _ _ _

is displayed.

3. Using Entry keys, enter 9 6 7 5.

4. As each digit is entered, the characters Y O R K are

displayed.

NOTE: If digits other than 9 6 7 5 are entered, YORK

is still displayed.

5. Press ENTER key.

NOTE: If digits other than 9 6 7 5 were entered in

step No. 4,

INVALID ACCESS CODE

is dis-

played when the ENTER key is pressed. If

this occurs, enter the correct access code

(9675) and proceed.

6.

ACCESS TO PROGRAM KEY AUTHORIZED

is displayed.

NOTE: Unless terminated by pressing the ACCESS

CODE key again, the operator will have ac-

cess to the PROGRAM key for 10 minutes.

When 10 minutes have elapsed, access to

PROGRAM key will be automatically dis-

abled and the operator must return to step

No. 1 to gain access.

22 YORK INTERNATIONAL

7. Press PROGRAM key.

8.

PROGRAM MODE, SELECT SETPOINT

is displayed.

9. Press MODE key.

10.The mode that has been previously selected will be

displayed as follows:

LOCAL MODE SELECTED

– or –

SERVICE MODE SELECTED

– or –

REMOTE MODE SELECTED

11.Press ADVANCE DAY key to scroll to desired mode.

Each time this key is pressed, a different mode is

displayed as above:

12.When the desired mode is displayed, press EN-

TER key.

13.

PROGRAM MODE, SELECT SETPOINT

is displayed.

14.Press ACCESS CODE key to exit PROGRAM mode

and terminate access to PROGRAM mode.

15.

ACCESS TO PROGRAM MODE DISABLED

is displayed.

COMPRESSOR SWITCH

(See Fig. 13, page 19.)

This rocker switch is used to locally operate the com-

pressor. It is used to start, run and stop the compres-

sor. Also, it resets the Control Center after a safety

shutdown.

To START* chiller compressor in LOCAL mode:

Move COMPRESSOR switch from STOP/RESET

to START position. Switch will spring-return to RUN

position.

To STOP compressor:

Move switch from RUN to STOP/RESET position.

To RESET Control Center:

Following a safety shutdown, the operator is re-

quired to reset the Control Center prior to restart-

ing the system. Move switch from RUN to STOP/

RESET position.

*NOTE: The operator cannot start the compressor (us-

ing this switch) when the Control Center is in

REMOTE mode.

DISPLAY MESSAGES

The following displayed messages will be automatically

displayed unless the operator is requesting additional

information via the keypad.

SYSTEM RUN - CURRENT LIMIT IN EFFECT

Displayed when the chiller is running, and the motor

current is equal-to or greater-than the operator-pro-

grammed “XXX % FLA” current limit value. When the

motor current reaches 100% of this value, the pre-

rotation vanes are not permitted to open further. If the

current continues to rise to 104% of this value, the

vanes will be driven closed – not fully closed; only far

enough to allow the current to decrease to a value less

than 104% of the operator-programmed “XXX % FLA”

current limit.

For example:

With the operator-programmed “% CURRENT LIMIT”

set at 50% and the FLA of the chiller equal to 200A, the

current limit circuit would perform as follows:

(100%) (50% x FLA) = Vanes inhibited from open-

ing further.

(104%) (50% x FLA) = Vanes driven toward close

position.

YORK INTERNATIONAL 23

FORM 160.49-O2

Therefore:

(100%) (50% x 200) = 100A = Vanes stop open-

ing

(104%) (50% x 200) = 104A = Vanes driven to-

ward close position.

SYSTEM RUN – AUTO VANES

Displayed when the chiller is running, the MicroCom-

puter Control Center is in SERVICE mode, and the

vanes are operating in AUTO mode.

SYSTEM RUN – VANES OPENING

Displayed when the chiller is running, the MicroCom-

puter Control Center is in SERVICE mode with:

• The vanes operating in AUTO mode and opening to

maintain the leaving chilled water temperature

setpoint. – or –

• The operator has pressed the vanes OPEN key on

the keypad.

SYSTEM RUN – VANES CLOSING

Displayed when the chiller is running, the MicroCom-

puter Control Center is in SERVICE mode with:

• The vanes operating in AUTO mode and closing to

maintain the leaving chilled water temperature

setpoint. – or –

• The operator has pressed the vanes CLOSE key on

the keypad.

SYSTEM RUN - VANES HOLDING

Displayed when the chiller is running, the MicroCom-

puter Control Center is in SERVICE mode, and the

operator has pressed the vanes HOLD key.

SYS READY TO START – VANES OPENING

Displayed when the chiller is running and the operator

has pressed the vanes OPEN key on the keypad.

SYS READY TO START – VANES CLOSING

Displayed when the chiller is not running and the op-

erator has pressed the vanes CLOSE key on the key-

pad.

SYS READY TO START – VANES HOLDING

Displayed when the chiller is running and the operator

has pressed the vanes HOLD key on the keypad.

SYSTEM RUN – LEVEL VALVE OPENING

Displayed as a foreground message when manual re-

frigerant level control has been selected using the “Spe-

cial Setpoints Procedure” in Service manual, Form

160.49-M3 and operating in SERVICE mode. Indicates

an “OPEN” command is being output to the variable

orifice. Manual level control should be selected only by

a qualified service technician.

SYSTEM RUN – LEVEL VALVE CLOSING

Displayed as a foreground message when manual re-

frigerant level control has been selected using the “Spe-

cial Setpoints Procedure” in Service manual, Form

160.49-M3 and operating in SERVICE mode. Indicates

a “CLOSE” command is being output to the variable

orifice. Manual level control should be selected only by

a qualified service technician.

SYSTEM RUN – AUTO LEVEL CONTROL

Displayed as a foreground message when manual re-

frigerant level control has been selected using the “Spe-

cial Setpoints Procedure” in Service manual, Form

160.49-M3 and operating in SERVICE mode. Indicates

that neither a “CLOSE” nor “OPEN” command is being

output to the variable orifice but is in “AUTO” mode.

Manual level control should be selected only by a quali-

fied service technician.

SYSTEM RUN – LOW PRESSURE LIMIT IN EFFECT

Displayed when the chiller is running and the evapora-

tor pressure falls to 56.2 PSIG (R-22); 27 PSIG (R-

134a). Simultaneously, the pre-rotation vanes will be

prevented from further opening. This action maintains

chiller operation to prevent low-evaporator-pressure

shutdown at 54.3 PSIG (R-22); 25 PSIG (R-134a).

When the evaporator pressure rises to 57.5 PSIG (R-

22); 28 PSIG (R-134a), the vanes will be permitted to

open. Low pressure limit feature is not used when pro-

gram jumper (JP3) is cut (Brine application).

SYSTEM RUN – HIGH PRESSURE LIMIT IN EFFECT

Displayed when the chiller is running and the condenser

pressure rises to 246.3 PSIG (R-22); 162.5 PSIG (R-

134a). Simultaneously, the pre-rotation vanes will be

inhibited from further opening. This action occurs to

prevent system shutdown on high condenser pressure

24 YORK INTERNATIONAL

at 265 PSIG (R-22); 180 PSIG (R-134a). When the con-

denser pressure falls to 245 PSIG (R-22); 160 PSIG

(R-134a), the vanes will be permitted to open.

SYSTEM RUN – PRESSURE STATUS

Displayed when the chiller is running. It instructs the

operator to press the STATUS key, whereupon one of

the following messages will be displayed:

•

WARNING: COND OR EVAP TRANSDUCER ERROR

Indicates a probable condenser or evaporator trans-

ducer problem, because the output is unreasonable.

The microprocessor arrives at this conclusion by

subtracting the evaporator transducer output from

the condenser transducer output. The result must be

zero or some positive number. If the result is a nega-

tive number, it concludes that there is a probable

condenser or evaporator transducer problem. This

function is inhibited for the first 10 minutes of chiller

run-time, and is checked every 10 minutes thereaf-

ter. Message is reset by pressing the WARNING RE-

SET key in the Service mode.

NOTE: If the STATUS key is arbitrarily pressed, with-

out the operator being prompted by the

PRESS STATUS

message, the following message shall be displayed.

NO MALFUNCTION DETECTED

WARNING – REFRIGERANT LEVEL OUT OF RANGE

Displayed when the refrigerant level sensor output goes

to > 4.4VDC. While this is displayed, the variable ori-

fice is driven open until the level is within range. This

message is automatically cleared when output is within

range.

SYSTEM RUN – LEAVING TEMP CONTROL

Displayed while the chiller is running. Indicates that

the pre-rotation vanes are being controlled by the leaving

chilled water temperature (LCWT). This is the normal

mode of chiller operation. Thus, if the LCWT is above

the setpoint, but pulling down rapidly, the vanes will

pulse closed as the LCW nears the setpoint.

SYSTEM READY TO START

Indicates that the system is not running, but will start

upon application of a start signal.

SYSTEM SHUTDOWN – PRESS STATUS

Displayed when chiller is shut down on a cycling shut-

down, safety shutdown (operator must move the COM-

PRESSOR switch to STOP/RESET in order to restart)

or operator-initiated shutdown (within 30 minutes of

initial start-up). The status message consists of the

day and time of shutdown, cause of shutdown, and

type of restart required. Upon pressing STATUS key,

System Shutdown Message will be displayed for 2 sec-

onds and then return to

SYSTEM SHUTDOWN – PRESS STATUS

Display can be held indefinitely by depressing DIS-

PLAY key. For examples of System Shutdown Mes-

sages, see below.

Chiller was shut down on Monday at 10:00 AM be-

cause the LCWT has decreased to a value that is 4°F

below the operator-programmed chilled liquid tempera-

ture setpoint. However, if the setpoint is less than 40°F,

the chiller will always shut down at 36°F. Further, if the

chiller is running and the setpoint is changed, the (Low

Water Temperature) cutout will be 36°F for 10 minutes

in order to eliminate nuisance trips. Finally, for brine

chilling applications, the LWT cutout is always 4°F be-

low the setpoint. (The water jumper on the Micro Board

must be removed for a brine unit.)

MON XX:XX AM – FLOW SWITCH – AUTOSTART

Chiller is shut down because a chilled-liquid flow switch

has opened. The flow switch must open for a minimum

of 2 seconds in order to cause a shutdown. The flow

switch is checked 25 seconds into “Start Sequence

Initiated” and continuously thereafter.

MON XX:XX AM – SYSTEM CYCLING – AUTOSTART

A remote command (computer relay contact or manual

switch) connected to the Remote/Local cycling input

of the digital input board has shut down the chiller.

MON XX:XX AM – MULTI UNIT CYCLING – AUTOSTART

Lead/Lag sequence control accessory has shut down

the chiller.

MON XX:XX AM – POWER FAILURE – AUTOSTART

The chiller is shut down because there has been a

power interruption or failure. The chiller will automati-

cally restart when power is restored. This message

SYSTEM SHUTDOWN MESSAGES

Day of Week Cause of Shutdown

Time of Day Type of Restart

MON 10:00 AM – LOW WATER TEMP – AUTOSTART

YORK INTERNATIONAL 25

FORM 160.49-O2

will be displayed if the Micro Board is configured for

AUTO-RESTART AFTER POWER FAILURE. The Mi-

cro Board is factory set for manual restart after power

failure. To convert it to auto-restart after power failure,

remove one of the two-pin program jumpers from the

cloth bag located inside the Control Center and place it

on the terminals labeled “Auto R” (J60) on the Micro

Board.

MON XX:XX AM – POWER FAILURE

The chiller is shut down because there has been a

power interruption or failure. When power is restored,

the chiller can be restarted by pressing the COMPRES-

SOR switch to STOP/RESET position and then to

START position. This message will be displayed if the

Micro Board is configured for MANUAL RESTART AF-

TER POWER FAILURE. The Micro Board is factory

set for manual restart after power failure. This has been

accomplished by removing the two-pin jumper from

the terminals labeled “Auto R” (J60) on the Micro Board.

AC UNDERVOLTAGE – AUTOSTART

The chiller is shut down because the MicroComputer

Control Center was in RUN mode, displaying

SYSTEM RUN – LEAVING TEMP CONTROL

, but the motor

current was less than 10% FLA for 25 continuous sec-

onds. This is indicative of an AC undervoltage condi-

tion that has caused the start relay (1R) in the Micro-

Computer Control Center to de-energize. This condi-

tion is checked when the MicroComputer Control Cen-

ter goes into RUN mode (after 30 second pre-lube).

This condition can be caused by failure of any compo-

nent that would cause a loss of the start signal from

the Control Center. In essence, this check assures

that the compressor is running when the Control Cen-

ter is displaying

SYSTEM RUN – LEAVING TEMP CONTROL .

This check is not performed when program jumper JP4

is removed (Steam Turbine applications).

MON XX:XX AM – INTERNAL CLOCK – AUTOSTART

The operator-programmed daily stop schedule has shut

down the chiller. The chiller will automatically restart

when the operator-programmed daily start schedule

indicates a start. It can be overriddden by pressing the

COMPRESSOR switch to the START position.

REMOTE STOP

This message will be displayed when a remote device

(typically an Energy Management System) has com-

manded the chiller to shut down. The chiller will restart

upon application of a separate start signal from the

remote device. This message will only be displayed

when Control Center is in REMOTE mode.

ANTI-RECYCLE, XX MIN LEFT

The chiller may not restart more frequently than every

30 minutes. Displayed when chiller is shut down and

there is time remaining on the anti-recycle timer. In

normal operation, chiller cannot be restarted until

ANTI-RECYCLE, 00 MIN LEFT

is displayed. However, when

servicing the chiller, it may be desirable to inhibit this

30-minute timer. If so, simply install a jumper plug in

the unmarked terminals of the Micro Board directly

under Auto-Restart jack.

This feature eliminated when program jumper JP4 is

removed (Steam Turbine applications).

WARNING: Remove this jumper after servicing.

Failure to do this voids the Warranty.

MON XX:XX AM – LOW EVAP PRESSURE

The chiller is shut down because the evaporator pres-

sure has decreased to 54.3 PSIG (R-22); 25.0 PSIG

(R-134a). The chiller will be allowed to start when the

pressure increases to 54.4 PSIG (R-22); 25.1 PSIG

(R-134a). To restart chiller, press the COMPRESSOR

switch to the STOP/RESET position and then to the

START position.

MON XX:XX AM – LOW EVAP PRESSURE – BRINE

The chiller is shut down because the brine Low Evapo-

rator Pressure (LEP, not included with standard Con-

trol Center) safety contacts have opened. The brine

LEP safety is located external to the Control Center.

Safety cut-out settings will vary with the brine applica-

tion. To restart the chiller, wait until the safety contacts

close, press the COMPRESSOR switch to the STOP/

RESET position and then to the START position.

MON XX:XX AM – LOW OIL PRESSURE

The chiller is shut down because the oil pressure has

decreased to 15 PSID while running, or never achieved

25 PSID prior to compressor start during the oil pump

pre-lube run. The chiller will be allowed to restart when

the pressure increases to 25 PSID. Differential pres-

sure is sensed by two pressure transducers. To re-

start chiller, press COMPRESSOR switch to STOP/

RESET position and then to the START position.

MON XX:XX AM – HIGH PRESSURE

The chiller is shut down because condenser pressure

26 YORK INTERNATIONAL

has increased to 265 PSIG (R-22); 180 PSIG (R-134a).

System will be allowed to restart when pressure de-

creases to 205 PSIG (R-22); 120 PSIG (R-134a). Pres-

sure is sensed by a High Pressure (HP) safety control

that is located on a mounting bracket above the oil-

pump starter located on the condenser. This message

is prompted by the opening of the HP safety control

contacts. To restart chiller, press COMPRESSOR

switch to the STOP/RESET position and then to the

START position.

MON XX:XX AM – EVAP TRANS OR PROBE ERROR

The chiller is shut down because the leaving chilled

water temperature minus the evaporator saturation tem-

perature is outside the range of –2.5°F to +25°F con-

tinuously for 10 minutes. To restart the chiller, press

COMPRESSOR switch to STOP/RESET switch to

STOP/RESET position and then to START position. On

Brine applications (program jumper JP3 removed), this

check is not performed when the evaporator transducer

is reading a pressure below its “out-of-range” thresh-

old.

On Steam Turbine applications (Micro Board program

jumper JP4 removed), with EPROM version C.02F

(T).12 or later, this check is bypassed for the first 20

minutes of chiller run time and then performed at the

regular 10 minute intervals thereafter. This is to allow

for the additional time required to decrease the evapo-

rator pressure due to the longer acceleration time of

the steam turbine.

MON XX:XX AM – MOTOR CONTROLLER – EXT. RESET

The chiller is shut down because a current module

(CM-2 Electro-Mechanical starter application), or the

YORK Solid State Starter or the Variable Speed Drive

initiated a shutdown. To restart system, reset the ex-

ternal device that caused the shutdown. The chiller will

then automatically restart.

NOTE: The following motor controller shutdowns do

not require an external reset to restart chiller.

Solid State Starter 110°F start inhibit. Anytime the

chiller has been shut down for any reason, this mes-

sage will be displayed until the SCR heatsink tempera-

tures decrease to below 110°F.

MON XX:XX AM – POWER FAULT – AUTOSTART

The chiller is shut down because of a Solid State Starter

or current module (CM-2 Electro-Mechanical starter

application) “Power Fault” shutdown. The chiller will

automatically restart. This function is sensed by the

motor controller input to the digital input board. A power-

fault shutdown is initiated by the motor controller con-

tacts (CM-1) opening and reclosing in one second. If

Solid State Starter application, the shutdown could have

been caused by any of the following reasons. The ap-

propriate light on the Solid State Starter Logic Board

will be illuminated.

• Phase rotation/loss

• Trigger Board out of lock (OOL)

• Power Fault

• Half Phase

MON XX:XX AM – HIGH DISCHARGE TEMP

The chiller is shut down because the discharge tem-

perature has increased to 220°F. The system will be

allowed to restart when the temperature has decreased

to 219°F. Temperature is sensed by a thermistor RT2.

To restart the chiller, press COMPRESSOR switch to

STOP/RESET position and then to the START posi-

tion.

MON XX:XX AM – HIGH OIL TEMP

The chiller is shut down because the oil temperature

has increased to 180°F. The system will be allowed to

restart when the temperature decreases to 179°F. The

temperature is sensed by thermistor RT3. To restart

the chiller, press COMPRESSOR switch to STOP/RE-

SET position and then to the START position.

MON XX:XX AM – OIL PRESSURE TRANSDUCER

The chiller is shut down because the oil pressure has

increased to 125 PSID (during the first 7 minutes of

compressor operation) 60 PSID (after the first minutes

of compressor operation). The chiller will be allowed to

restart when the oil pressure decreases to 59 PSID. To

restart the chiller, press COMPRESSOR switch to

STOP/RESET position and then to the START posi-

tion.

MON XX:XX AM – FAULTY COND PRESSURE XDCR

The chiller is shut down because the condenser trans-

ducer is indicating a pressure of less than 24.2 PSIG

(R-22), 6.8 PSIG (R-134a); or a pressure greater than

300 PSIG (R-22 or R-134a). This is generally indica-

tive of a defective condenser transducer or the trans-

ducer has been disconnected. After the problem has

been corrected, the chiller can be restarted. To restart,

press COMPRESSOR switch to STOP/RESET posi-

tion and then to START position.

MON XX:XX AM – FAULTY OIL PRESSURE XDCR

The chiller is shut down because either the high side

or low side oil pressure transducer was out-of-range

(displaying x’s) while chiller was running. To restart

YORK INTERNATIONAL 27

FORM 160.49-O2

chiller, press COMPRESSOR switch to STOP/RESET

position and then to START position.

VANE MOTOR SWITCH OPEN

The chiller is shut down because a system-start se-

quence has been initiated, but the pre-rotation vanes

are not fully closed.

MON XX:XX AM – STARTER MALFUNCTION DETECTED

The chiller is shut down because the Control Center

has detected a motor-current value greater than 15%

FLA for 10 seconds minimum anytime when the com-

pressor-start signal is not energized. To restart the

chiller, press COMPRESSOR switch to STOP/RESET

position and then to the START position.

MON XX:XX AM – PROGRAM INITIATED RESET

The chiller is shut down because Micro Board did not

receive a hardware-generated interrupt on schedule.

Typical is an Analog/Digital Converter interrupt. This

message is indicative of a Micro Board hardware fail-

ure or electrical noise on Micro Board. The chiller will

automatically restart. This message indicates that the

watchdog timer-circuit has reset the microprocessor.

This occurs when the time needed to step through pro-

gram is longer than allowable, thus the software pro-

gram is initialized at its beginning.

SYSTEM READY TO START – PRESS STATUS

The chiller was shut down on a safety shutdown and

will start upon application of a local or remote start

signal. Since the message states that the chiller is

“Ready to Start”, it means that the shutdown no longer

exists and the Control Center has been manually re-

set. When the STATUS key is pressed, a message is

displayed that describes the reason for shutdown. The

message will be displayed for 2 seconds and then re-

turn to

SYSTEM READY TO START – PRESS STATUS

.

Those messages that could be displayed are any of

the previously described safety-shutdown messages

or warning messages. They can be cleared from the

display by entering Service mode and pressing WARN-

ING RESET key. Or, the message will be cleared by

initiating a compressor start.

START SEQUENCE INITIATED

Indicates that the Micro Board has received a local or

remote start signal and has initiated the chiller start-

up routine.

This is the compressor pre-lube period. The duration

of this period is controlled by the “Prerun” (JP6) wire

jumper on the Micro Board as follows:

FUNCTION JUMPER POSITION

50 Sec. Oil Pump Prerun Installed

180 Sec. Oil Pump Prerun Cut

SYSTEM COASTDOWN

Displayed while motor is decelerating after a chiller

shutdown. The oil pump is running during this period.

The duration of this period is 150 seconds.

If unit is configured for a Steam Turbine application

(program jumper JP4 removed), this period is extended

to allow for a longer coastdown time. EPROM version

C.02F(T).11 provides a 6 minute coastdown period.

EPROM version C.02F(T).12 or later provides a 10

minute coastdown period.

MON XX:XX AM – MTR PHASE CURRENT UNBALANCE

(Solid State Starter applications only)

The chiller is shut down because the compressor-motor

current was unbalanced while the chiller was running.

The current balance is only checked after the motor

has been running for a minimum of 45 seconds and the

motor current is 80% FLA or greater. If the current in

any phase deviates from the average (a + b3+ c ) current

by greater than 30% for a minimum of 45 consecutive

seconds, a shutdown is initiated. To restart the sys-

tem, press the COMPRESSOR switch to STOP/RE-

SET position and then to the START position. An ex-

ample of the conditions for shutdown is as follows:

IF:

I∅A= 200A

I∅B= 200A

I∅C= 118A

THEN:

IAV = 200 + 200 + 118

3

IAV = 173A

IACCEPTABLE = 173 ± 30% = 121A or 225A

THEREFORE:

Since I∅C = 118A which is less than the accept-

able 121A, the chiller would shut down if this

unbalance exists for 45 consecutive seconds.

MON XX:XX AM – LOW LINE VOLTAGE

(Solid State Starter applications only)

Chiller is shut down because the voltage in any phase

of line voltage has decreased below the under-volt-

age-shutdown threshold for 20 consecutive seconds,

28 YORK INTERNATIONAL

or failed to achieve the minimum required starting line-

voltage. Refer to explanation under “System Setpoints

– SSS Motor Current/Volts”, page 11. The system will

automatically restart when all phases of line voltage

increase to the minimum required starting voltage.

MON XX:XX AM

–

HIGH LINE VOLTAGE

(Solid State Starter applications only)

Chiller is shut down because the voltage in any phase

of line voltage has increased above the over-voltage

threshold for 20 consecutive seconds. Refer to expla-

nation under “System Setpoints – SSS Motor Current/

Volts”, page 11. The system will automatically restart

when all phases of line voltage decrease to the maxi-

mum allowable line voltage to start the chiller.

MON 09:30 AM – LOW OIL TEMPERATURE – AUTOSTART

The chiller is running and the oil temperature (as indi-

cated by thermistor RT3) falls below 55°F, the chiller

will shut down and display this message. The chiller

will automatically restart when the oil temperature in-

creases to >71°F AND is greater than the condenser

saturated temperature by 20°F or 30°F depending upon

how long the chiller was shut down. Refer to the mes-

sage “

MON XX:XX AM LOW OIL TEMP DIFF – AUTOSTART

”.

MON XX:XX AM – LOW OIL TEMP DIFF – AUTOSTART

Indicates the chiller is shut down for one of the follow-

ing reasons:

1. The chiller has been shut down for 30 minutes or

less and the oil temperature minus the condenser

saturation temperature is less than 30°F.

– or –

2. The chiller has been shut down for more than 30

minutes and the oil temperature minus the con-

denser saturation temperature is less than 40°F.

– or –

3. Following a power failure, the oil temperature mi-

nus the condenser saturation temperature is less

than 40°F.

The chiller will restart automatically after the condition

clears if the COMPRESSOR switch is in the RUN po-

sition.

NOTE: This check is made only when the chiller is

shut down. It is not checked when the chiller is

running or in “Start Sequence Initiated”.

DAY – TIME – OIL PRESSURE XDCR ERROR

Indicates the chiller has shut down because the differ-

ence between the High Side Oil Pressure Transducer

Output and the Low Side Transducer Output was greater

than 15.0 PSID during the “Transducer Auto-Zeroing

Sequence” that occurs 10 seconds after a chiller start

is initiated. Message is displayed immediately after the

Auto-Zeroing sequence has completed. This indicates

that one of the transduce outputs is incorrect, possibly

due to an incorrect or defective transducer. To restart

the chiller, press COMPRESSOR switch to STOP/

RESET position and then to START position.

MON XX:XX AM – FAULTY DISCHARGE TEMP SENSOR

Whenever the discharge temperature falls below 30°F,

or the discharge temperature sensor is disconnected

from the Micro Board, the preceding message will ap-

pear. To restart the system when the discharge tem-

perature rises or the sensor has been connected, press

the COMPRESSOR switch to the STOP/RESET posi-

tion and then to the START position.

MON XX:XX AM – PROX SENSOR SAFETY SHUTDOWN

The chiller is shut down because the “Proximity/Tem-

perature Sensor” has detected that the distance be-

tween the compressor high speed thrust collar and the

sensor probe has increased > 10 mils or decreased >

20 mils (25 mils with EPROM version C.02F(T).12 or

later) from the “Reference Position”.

NOTE: With EPROM version C.02F (T).11, if the ref-

erence position is < 42 mils, the minimum al-

lowed distance is 22 mils. With EPROM ver-

sion C.02F(T).12 or later, if the reference posi-

tion is < 44 mils, the minimum allowed distance

is 19 mils.

IMPORTANT: If the chiller has shut down displaying

this message, it cannot be restarted until a qualified

service technician performs a visual inspection of the

high speed thrust bearing and performs a special reset

procedure. This special reset procedure is detailed in

YORK Service manual, Form 160.49-M3. Failure to

perform the visual inspection prior to restarting the

chiller could result in severe compressor damage!!!

DAY – TIME – FAULTY PROXIMITY PROBE

The chiller has shut down because the “Proximity/Tem-

perature Sensor” has detected that the distance be-

tween the compressor high speed thrust collar and the

sensor probe has decreased to ≤ 17 mils.

YORK INTERNATIONAL 29

FORM 160.49-O2

IMPORTANT!!!: Although this message is generally

indicative of a defective proximity probe, it is possible

that the compressor has been damaged. If the high

speed thrust bearing is not inspected by a qualified

service technician prior to starting the chiller, further

severe compressor damage could result. The chiller

cannot be restarted until the “Special Reset Proce-

dure” in YORK Service manual, Form 160.49-M3 is per-

formed by a qualified service technician.

MON XX:XX AM – HIGH SPEED DRAIN TEMP

The chiller has shut down because the “Proximity/Tem-

perature Sensor” has detected the temperature of the

high speed drain line has reached 250.0°F or greater.

IMPORTANT: If the chiller has shut down displaying

this message, it cannot be restarted until a qualified

service technician performs visual inspection of the

high speed thrust bearing and performs a special reset

procedure. This special reset procedure is detailed in

YORK Service manual, Form 160.49-M3. Failure to

perform the visual inspection prior to restarting the

chiller could result in severe compressor damage!!!

MON XX:XX AM – OPEN DRAIN TEMP THERMOCOUPLE

The chiller is shut down because the “Proximity/Tem-

perature Sensor” thermocouple or high speed drain tem-

perature wiring between the “Proximity/Temperature

Sensor” module and the MicroComputer Control Cen-

ter has been disconnected or has a poor electrical con-

nection.

IMPORTANT: Open thermocouple shutdowns would

typically indicate hardware or wiring defects and should

not result in any damage to the compressor high speed

thrust bearing. Therefore, a bearing inspection is not

required. However, due to the critical nature of these

circuits, anytime this shutdown occurs, a special re-

set procedure must be performed by a qualified ser-

vice technician before the chiller can be restarted.

This procedure is detailed in Service manual, Form

160.49-M3.

MON XX:XX AM – DC UNDERVOLTAGE

The “Proximity/Temperature Sensor” module becomes

unstable in operation when the +24VDC supply de-

creases to +17VDC. Therefore, the Micro Board moni-

tors the +24VDC supply and when it decreases to

+19VDC, it shuts down the chiller and displays this

message, preventing invalid “Proximity Sensor Safety”

or “High Speed Drain Temp” safety shutdowns. The

chiller will automatically restart when the voltage in-

creases to greater than +19.7 VDC.

MON XX:XX AM – AUX SAFETY SHUTDOWN

The system is shut down because an external device,

connected to digital input board TB1-31 (Auxiliary Safety

Shutdown Input), has initiated a system shutdown. This

input is a general purpose input that can be used to

annunciate a user-defined safety shutdown. To restart

chiller, press COMPRESSOR switch to STOP-RESET

position and then to START position.

REPLACE RTC. U16 – REPROGRAM SETPOINTS

Indicates that the battery located inside the REAL-

TIME CLOCK IC chip (U16 on the Micro Board) is

defective. This battery provides back-up power to the

RTC memory (RAM) in the event of a utility AC power

failure. This assures the system setpoints will be main-

tained. If this message appears, the RTC IC chip (U16)

on the Micro Board must be replaced. If there had been

a power failure while this message is displayed, the

setpoints will have been lost and must be repro-

grammed. Order a replacement RTC IC chip (YORK

part number 031-00955-000) from the YORK Parts Dis-

tribution Center. With AC power removed from system,

locate RTC chip U16 on the Micro Board and remove

existing RTC chip from socket and discard. Observe

anti-static precautions and install new RTC chip in

socket. Assure proper IC orientation – orientation notch

must be UP. (Refer to Fig. 14.)

FIG. 14 – MICROCOMPUTER CONTROL CENTER

LOCATION OF REAL TIME CLOCK U16

RTC IC CHIP

24673A

MICRO BOARD

U16 RTC

IC CHIP

REAL

TIME

CLOCK

30 YORK INTERNATIONAL

SECTION 3

SYSTEM OPERATING PROCEDURES

WARNING

OIL HEATERS

If the oil heater is de-energized during a shut-

down period, they must be energized for 12 hours

prior to starting compressor, or remove all oil and

recharge compressor with new oil. (See “Charg-

ing Unit With Oil”, page 43.)

NOTE: The oil heater is thermostatically controlled

and remains energized as long as the

fused disconnect switch to the starter or

turbo-modulator is energized.

CHECKING THE OIL LEVEL IN THE OIL

RESERVOIR

Proper operating oil level – the middle of the up-

per sight glass.

If the oil is excessively high after start-up, the

excess oil may be drained from the oil filter drain

valve while the compressor is running.

If oil level is low, oil should be added to the com-

pressor. (See “Charging Unit With Oil”, page 43.)

START-UP PROCEDURE

PRE-STARTING

Prior to starting the chiller, observe the MicroCom-

puter Control Center. Make sure the display reads

SYSTEM READY TO START

.

To pre-start the chiller, use the following procedure:

1. Oil Heater – The oil heater must be energized for

12 hours prior to starting the chiller. The unit will

not start if the oil is less than 71°F. If not possible

the compressor oil should be drained and new oil

must be charged into the oil sump. (See “Charging

Unit With Oil”, page 43.)

2. Oil Pump – To check, press and release the

MANUAL OIL PUMP key under Service on the

Control Center. The oil pump will run for 10 min-

utes and shut down. Press and release the

MANUAL OIL PUMP key to stop the operation of

the oil pump for less than 10 minutes of operation.

3. Pre-Rotation Vanes – To perform this test the

starter interlock terminals 3 and 4 must be

jumpered to allow vanes to open (remove the

jumper after test). Make sure the Control Center

is in the SERVICE mode, then press the prerotation

vanes OPEN and CLOSE keys to observe the

operation of the prerotation vanes. The Control

Center supplies a signal to operate the prerotation

vanes. The movement of the vanes will be dis-

played on the Control Center. The display readout

is active whenever power is supplied to the Con-

trol Center. Return from the SERVICE mode to

LOCAL, PROGRAM, or REMOTE mode to suit

the method of operation selected for the chiller

application. Refer to “Section 2”.

4. % Current Limit – Press the % CURRENT LIMIT

setpoint key on the Control Center. The “Display”

should read

CURRENT LIMIT = 100% FLA

on (Solid

State Starter units only, the display is

CURRENT LIMIT = 100% FLA, MTR CUR = XXXX FLA

)

if the Control Center was not programmed. If the

setpoint is not 100% and was predetermined for

the job application the Control Center should be

programmed to that specification. To program, re-

fer to “Section 2”.

5. All Control Center setpoints should be programmed

before the chiller is started. (Refer to “Section 2”.)

Prior to start, the clock must be programmed for

the proper day and time. Any setpoints which are

desired to be changed may be programmed. If not

programmed the “default” value setpoints are as

follows:

LCWT = 45°F

% Current Limit = 100% FLA

Pulldown Demand = None

Clock = Sun 12:00 A.M.

Daily Schedule = None

Holiday = None

Remote Reset Temp. Range = 20°F

Data Logger = No operation

YORK INTERNATIONAL 31

FORM 160.49-O2

START-UP

1. If the chilled water pump is manually operated,

start the pump. The Control Center will not allow

the chiller to start unless chilled liquid flow is es-

tablished through the unit. (A field supplied chilled

water flow switch is required.) If the chilled liquid

pump is wired to the MicroComputer Control Cen-

ter the pump will automatically start, therefore,

this step is not necessary.

2. To start the chiller, press the COMPRESSOR

START switch. This switch will automatically spring

return to the RUN position. (If the unit was previ-

ously started, press the STOP/RESET side of the

COMPRESSOR switch and then press the START

side of the switch to start the chiller.) When the

start switch is energized, the Control Center is

placed in an operating mode and any malfunction

will be noted by messages on the 40 character

alphanumeric display. (See Fig. 3.)

NOTE: Any malfunctions which occur during

STOP/RESET are also displayed.

When the chiller is shut down, the prerotation vanes

will close automatically to prevent loading the com-

pressor on start-up. When the prerotation vanes

are fully closed the “Display” will read

SYSTEM READY TO START – VANES CLOSED

when in SERVICE mode.

When the chiller starts to operate, the following auto-

matic sequences are initiated: (Refer to Fig. 15, “Chiller

Starting & Shutdown Sequence Chart”.)

1. The MicroComputer Control center alphanumeric

display message will read

START SEQUENCE INITIATED

for the first 50 seconds of the starting sequence,

(3 minutes if Micro Board JP6 removed).

2. The compressor vent line solenoid valve will open

after the first 5.83 minutes of operation. The sole-

noid will close automatically after the compressor

shuts down.

3. The 1R-1 contacts of the 1R start relay will re-

main open for the first 50 seconds of oil pump

operation. These contacts will close, starting the

compressor motor and the condenser water pump

at the end of the 50 second period.

4. The oil pump will start to circulate oil for a 50

second pre-run to establish oil flow and adequate

lubrication to all bearings, gears, and rotating sur-

faces within the compressor.

The high and low oil pressure transducers (OP)

and the oil temperature sensor (RT3) will sense

any malfunction in the lubrication system and ac-

tivate one of the following display messages:

DAY 10:30 AM – LOW OIL PRESSURE

DAY 10:30 AM – HIGH OIL TEMPERATURE

DAY 10:30 AM – LOW OIL TEMP – AUTOSTART

DAY 11:30 AM – OIL PRESSURE TRANSDUCER

5. The anti-recycle timer software function will oper-

ate after the 50 seconds of pre-run time. At this

time, the timer will be initiated and will run for 30

minutes after the compressor starts. If the chiller

shuts down during this period of time, it cannot be

started until the timer completes the 30 minute

cycle.

6. The chilled liquid pump contacts will close start-

ing the chilled liquid pump to allow liquid flow

through the cooler when the COMPRESSOR start

switch is energized.

7. After the first 50 seconds of operation, the com-

pressor will start and the Control Center display

message will read

SYSTEM RUN – CURRENT LIMIT IN EFFECT

while the

motor is accelerating to full speed. When the mo-

tor reaches full speed and the current falls below

100% FLA the message will read

SYSTEM RUN – LEAVING TEMP. CONTROL

8. For additional display messages and information

pertaining to the operation of the MicroComputer

Control Center, refer to “Section 2”.

9. Low Oil Temp. Differential.

CHILLER OPERATION

After the compressor reaches its operating speed, the

Prerotation Vanes will begin to open under the control

of the Microprocessor Board which senses the leaving

chilled liquid temperature. The unit capacity will vary

to maintain the leaving CHILLED LIQUID TEMPERA-

TURE setpoint. The Prerotation Vanes are modulated

by an actuator under the control of the Microprocessor

Board. The vane control routine employs proportional

plus derivative (rate) control action. A drop in chilled

liquid temperature will cause the actuator to close the

Prerotation Vanes to decrease chiller capacity. When

the chilled liquid temperature rises, the actuator will

open the Prerotation Vanes to increase the capacity of

the chiller.

32 YORK INTERNATIONAL

However, the current draw (amperes) by the compres-

sor motor cannot exceed the setting of the % CUR-

RENT LIMIT at any time during the unit operation, since

the MicroComputer Control Center 40 to 100% three-

phase peak current limit software function, plus the 3-

phase 100% solid state overload current limiter (CM-

2) on Electro-Mechanical Starter applications or the

Solid State Starter current Limit function will override

the temperature control function and prevent the Pre-

rotation Vanes from opening beyond the % CURRENT

LIMIT setting.

If the load continues to decrease, after the Prerotation

Vanes are entirely closed, the chiller will be shut down

by the Low Water Temperature control (LWT) function

which is displayed on the Control Center as:

MON 10:30 AM – LOW WATER TEMPERATURE – AUTOSTART

This occurs when the leaving water temperature falls

to 4°F below setpoint or 36°F, whichever is higher. The

LWT is part of the Micro Board.

NOTE: If the temperature setpoint has been repro-

grammed within the last 10 minutes, the LWT

cutout is 36°F for 10 minutes.

Condenser Water Temperature Control

The YORK Millennium chiller is designed to use less

power by taking advantage of lower than design tem-

peratures that are naturally produced by cooling tow-

ers throughout the operating year. Exact control of con-

denser water such as a cooling tower bypass, is not

necessary for most installations. The chiller requires

only that the minimum condenser water temperature

SYSTEM STARTING & SHUTDOWN SEQUENCE

OPERATOR INITIATED

FIG. 15 – CHILLER STARTING SEQUENCE & SHUTDOWN SEQUENCE

NOTES: 1. REF. MICROBOARD PROGRAM JUMPER JP6

2. REF. MICROBOARD PROGRAM JUMPER JP4

(NOTE 2)

LD00952

YORK INTERNATIONAL 33

FORM 160.49-O2

be no lower than the value determined by referring to

the formula below:

100

Min. ECWT = LCHWT—C RANGE + 5 + (15 x % LOAD)

where:

ECWT = entering condensing water temperature

LCHWT = leaving chilled water temperature

C RANGE = condensing water temperature range

At start-up, the entering condenser water temperature

may be as much as 25°F colder than the standby re-

turn chilled water temperature. Cooling tower fan

cycling will normally provide adequate control of the

entering condenser water temperature on most instal-

lations.

CHECKING OPERATION

During operation, the following conditions should be

periodically checked:

1. On starting, the prerotation vanes should remain

closed until the compressor motor is up to speed

on the run winding; then the vane motor should cause

the vanes to modulate with load requirements.

2. Be sure the oil pump is operating while unit is run-

ning.

3. Check Oil Pressure display. A gradual decrease in

bearing oil pressure of 5 to 10 psi (with constant

suction and discharge pressures) may be an indi-

cation of a dirty filter. The filter should be replaced

when pressure loss is 30% or more of the original

pressure. The actual bearing oil pressure will vary

with compressor suction and discharge pressures.

When a new system is first operated under normal

full load conditions, the bearing oil pressure should

be recorded as a reference point with which to com-

pare subsequent readings.

OPERATING LOG SHEET

A permanent daily record of system operating condi-

tions (temperatures and pressures) recorded at regu-

lar intervals throughout each 24 hour operating period

should be kept.

An optional status printer is available for this purpose

or Fig. 16 shows a log sheet used by YORK Personnel

for recording test data on chiller systems. It is avail-

able from the factory in pads of 50 sheets each under

Form 160.44-F6 and may be obtained through the nearest

FIG. 16 – LIQUID CHILLER LOG SHEETS

*NOTE: These items can be printed by an electronic printer connected to TB8 of the Micro Board and pressing the PRINT key on the

Micro Board or automatically using the Data Logger feature.

LD00467 23889A

34 YORK INTERNATIONAL

YORK office. Automatic data logging is possible by

connecting the optional printer and programming the

DATA LOGGER function; refer to Form 160.49-N7.

An accurate record of readings serves as a valuable

reference for operating the system. Readings taken

when a system is newly installed will establish normal

conditions with which to compare later readings.

For example, an increase in condenser approach tem-

perature (condenser temperature minus leaving con-

denser water temperature) may be an indication of dirty

condenser tubes.

OPERATING INSPECTIONS – See Section 2

By following a regular inspection using the display read-

ings of the MicroComputer Control Center, and main-

tenance procedure, the operator will avoid serious op-

erating difficulty. The following list of inspections and

procedures should be used as a guide.

Daily

1. Check MicroComputer Control Center displays.

2. If the compressor is in operation, check the bear-

ing oil pressure by pressing OIL PRESSURE key

to read the display on the Control Center. Also check

the oil level in the oil reservoir. Operating oil level

should be between the upper and lower sight

glasses. Drain or add oil if necessary.

3. Check entering and leaving condenser water pres-

sure and temperatures for comparison with job de-

sign conditions. Condenser water temperatures can

be checked by pressing CONDENSER LIQUID

TEMPERATURES display key.

4. Check the entering and leaving chilled liquid tem-

peratures and evaporator pressure for comparison

with job design conditions. This can be accomplished

by pressing the CHILLED LIQUID TEMPS key and

the REFRIGERANT PRESSURES key.

5. Check the condenser saturation temperature (based

upon condenser pressure sensed by the condenser

transducer). Press the DISPLAY DATA key. This

key may be depressed repeatedly after depressing

the DISPLAY HOLD key to display three different

parameters.

6. Check the compressor discharge temperature.

Press DATA DISPLAY key. During normal opera-

tion discharge temperature should not exceed 220°F.

7. Check the compressor motor voltage and current

(amps) at E-M starter (or Variable Speed Drive), or

on the Control Center display for Solid State Starter

units.

8. Check for any signs of dirty or fouled condenser

tubes. (The temperature difference between water

leaving condenser and liquid refrigerant leaving the

condenser should not exceed the difference re-

corded for a new unit by more than 4°F.)

9. Press the STATUS key whenever the display indi-

cates so. This allows any warning messages to be

displayed.

Weekly

1. Check the refrigerant charge. (See “Checking The

Refrigerant Charge”, page 52.)

Quarterly

1. Perform chemical analysis of oil.

Semi-Annually (or more often as required)

1. Change and inspect compressor oil filter element.

2. Oil return system.

a. Change dehydrator.

b. Check nozzle of eductor for foreign particles.

3. Check controls and safety cutouts.

Annually (more often if necessary)

1. Drain and replace the oil in the compressor oil

sump. (See “Charging The Unit With Oil”, page 43.)

2. Cooler and Condenser.

a. Inspect and clean water strainers.

b. Inspect and clean tubes as required.

c. Inspect end sheets.

3. Compressor Drive Motor (See motor manufactur-

ers maintenance and service instruction supplied

with unit)

a. Clean air passages and windings per manufac-

turers instructions.

b. Meg motor windings – See Fig. 23 for details.

c. Re-lubricate ball bearings.

YORK INTERNATIONAL 35

FORM 160.49-O2

4. Inspect and service electrical components as nec-

essary.

5. Perform chemical analysis of system.

NEED FOR MAINTENANCE OR SERVICE

If the system is malfunctioning in any manner or the

unit is stopped by one of the safety controls, consult

the “Operation Analysis Chart”, pages 47 through 48

of this instruction. After consulting this chart, if you

are unable to make the proper repairs or adjustments

to start the compressor or the particular trouble con-

tinues to hinder the performance of the unit, please

call the nearest YORK District Office. Failure to report

constant troubles could damage the unit and increase

the cost of repairs considerably.

NORMAL AND SAFETY SYSTEM SHUTDOWNS

Normal and safety system shutdowns have been built

into the chiller to protect it from damage during certain

operating conditions. Therefore, it should be understood

that at certain pressures and temperatures the sys-

tem will be stopped automatically by controls that re-

spond to high temperatures, low temperatures, and low

and high pressures, etc. Table 1 is an explanation of

each specific shutdown. If the chiller shuts down on a

“Safety” shutdown, the display will read

SYSTEM SHUTDOWN – PRESS STATUS

Upon pressing the STATUS key, the day-of-week, time-

of-day and cause of shutdown is displayed. Safety shut-

downs require the operator to manually reset the Con-

trol Center prior to restarting the chiller. When the dis-

play reads

START SEQUENCE INITIATED

, the cause of the

safety shutdown is automatically cleared from the

memory.

SAFETY SHUTDOWNS

• Power Failure (If auto restart programming jumper is

not installed on the Micro Board)

• Low Evaporator Pressure

• Low Oil Pressure

• High Condenser Pressure

• Evaporator Transducer or Probe Error

• High Discharge Temp

• High Oil Temp

• Oil Pressure Transducer

• Starter Malfunction Detected

• Faulty Discharge Temp Sensor

• Aux. Safety Shutdown

• Motor Phase Current Unbalance (Solid State Starter

Unit only)

• Proximity sensor

• Faulty Prox. Probe

• Open Drain Thermocouple

If the chiller shuts down on a “Cycling” shutdown the

display will read

SYSTEM SHUTDOWN – PRESS STATUS

.

Upon pressing the STATUS key, the day-of-week, time-

of-day and cause of shutdown are displayed. These

shutdowns do not require the operator to manually re-

set the Control Center prior to re-starting the chiller.

The chiller will automatically restart when the cycling

condition is removed.

CYCLING SHUTDOWNS

• Power Failure (If auto re-start programming jumper

is installed on the Micro Board)

• Low Water Temp

• Flow Switch

• System Cycling

• Multi-Unit Cycling

• Internal Clock

• Anti-Recycle

• Motor Controller (Manual reset of the CM-2 module

on E-M starter units; the logic board of the Solid

State Starter may be required)

• Power Fault

• Program Initiated Reset

• Low Oil Temp

• AC Undervoltage

• DC Undervoltage

• Low Line Voltage (Solid State Starter units only)

• High Line Voltage (Solid State Starter units only)

• Low Oil Temp. Differential

STOPPING THE SYSTEM (See Fig. 3, page 6)

The MicroComputer Control Center can be programmed

to start and stop automatically (maximum, once each

day) whenever desired. Refer to “Section 2”. To stop

the chiller, proceed as follows:

1. Push the COMPRESSOR STOP/RESET switch. The

Control Center display will show

SYSTEM COASTDOWN

for 150 seconds. If unit is

configured for a STEAM TURBINE application (pro-

gram jumper JP4 removed), this period is extended

to allow for a longer coastdown time. EPROM ver-

sion C.02F(T).11 provides a 6 minute coastdown

36 YORK INTERNATIONAL

period. EPROM version C.02F(T).12 or later pro-

vides a 10 minute coastdown period. The compres-

sor, condenser water, and cooling tower fans will

stop automatically. The oil pump will continue to run

for coastdown period. The oil pump will then stop

automatically. Once stopped, the

SYSTEM COASTDOWN

display will be replaced by

SYSTEM READY TO START

.

2. Stop the chilled water pump (if not wired into the

MicroComputer Control Center, in which case it will

shut off automatically simultaneously with the oil

pump.) (The actual water pump contact operation

is dependent upon the postion of Micro Board jumper

J54.)

3. Open the switch to the cooling tower fan motors, if

used.

4. The compressor sump oil heater (thermostatically

controlled) is energized when the unit is stopped.

PROLONGED SHUTDOWN

If the chiller is to be shut down for an extended period

of time (for example, over the winter season), the fol-

lowing paragraphs outline the procedure to be followed.

1. Test all system joints for refrigerant leaks with a

leak detector. If any leaks are found, they should

be repaired before allowing the system to stand for

a long period of time.

During long idle periods, the tightness of the sys-

tem should be checked periodically.

2. If freezing temperatures are encountered while the

system is idle, carefully drain the cooling water from

the cooling tower, condenser, condenser pump, and

the chilled water system-chilled water pump and

coils.

Open the drains on the cooler and condenser liquid

heads to assure complete drainage. (If a Variable

Speed Drive, drain its water cooling system. If Solid

State Starter. drain water from starter cooling loop.)

3. Move jumper J-57 on the Micro Board from CLOCK

ON position (CLKON) to CLOCK OFF position

(CLKOFF) while 115VAC control power is applied.

This conserves the battery.

4. Open the main disconnect switches to the com-

pressor motor, condenser water pump and the chilled

water pump. Open the 115 volt circuit to the Control

Center.

START-UP AFTER PROLONGED SHUTDOWN

1. When putting the system into operation after pro-

longed shutdown (during the winter), remove all oil

from the compressor. Install a new filter element

and charge compressor with fresh oil. Move jumper

J-57 on the Micro Board from CLOCK OFF position

(CLKOFF) to CLOCK ON position (CLKON) and re-

set the clock. Energize the 115 volt circuit to the

Control Center to energize the compressor sump

oil heater for at least 12 hours.

2. Operate the Oil Pump (press and release the MAN-

UAL OIL PUMP key) until steady oil pressure is

established. Then press and release the OIL PUMP

key to stop operation of the oil pump. If the water

systems were drained, fill the condenser water cir-

cuit and chilled liquid circuit.

YORK INTERNATIONAL 37

FORM 160.49-O2

SECTION 4

SYSTEM COMPONENTS DESCRIPTION

27385A

FRONT VIEW

DUAL RELIEF

VALVES

MICROCOMPUTER

CONTROL CENTER

SUCTION

DISCHARGE

COMPRESSOR

ADAPTER MOTOR

SUPPORT & COVER

MOTOR

COOLER

REFRIGERANT

CHARGING VALVE

DEHYDRATOR

SIGHT

GLASSES

FIG. 17 – SYSTEM COMPONENTS

27382A

OIL PUMP

STARTER

DISCHARGE LINE

CONDENSER

OIL RESERVOIR/

PUMP

38 YORK INTERNATIONAL

GENERAL

The YORK Model YK Millennium Centrifugal Liquid

Chiller is completely factory-packaged including cooler,

condenser, compressor, motor, lubrication system,

MicroComputer Control Center, and all interconnect-

ing unit piping and wiring.

The initial charge of refrigerant and oil is supplied for

each unit. Oil is shipped in containers with the chiller.

Refrigerant is shipped to the jobsite in cylinders at the

time of installation.

The services of a YORK factory-trained, field service

representative are included to supervise the final leak

testing, charging and the initial start-up and concur-

rent operator instructions.

COMPRESSOR

The compressor is a single-stage centrifugal type pow-

ered by an open-drive electric motor.

The rotor assembly consists of a heat-treated alloy

steel drive shaft and impeller shaft with a cast alumi-

num, fully shrouded impeller. The impeller is designed

for balanced thrust and is dynamically balanced and

over-speed tested.

The inserted type journal and thrust bearings are fabri-

cated of aluminum alloy. Single helical gears with

crowned teeth are designed so that more than one tooth

is in contact at all times. Gears are integrally as-

sembled in the compressor rotor support and are film

lubricated. Each gear is individually mounted in its own

journal and thrust bearings.

The open-drive compressor shaft seal consists of a

spring-loaded, precision carbon ring, high temperature

elastomer “O” ring static seal, and stress-relieved, pre-

cision lapped collars. The seal is oil-flooded at all times

and is pressure-lubricated during operation.

CAPACITY CONTROL

Prerotation vanes (PRV) modulate chiller capacity from

100% to as low as 15% of design for normal air condi-

tioning applications. Operation is by an external, elec-

tric PRV actuator which automatically controls the vane

position to maintain a constant leaving chilled liquid

temperature.

COMPRESSOR LUBRICATION SYSTEM

(See Fig. 18)

The chiller lubrication system consists of the oil pump,

oil filter, oil cooler and all interconnecting oil piping and

passages. There are main points within the motor-com-

pressor which must be supplied with forced lubrication

as follows:

1. COMPRESSOR DRIVE SHAFT (Low Speed)

a. Shaft seal.

b. Front and rear journal bearings – one on each

side of driving gear.

c. Low speed thrust bearing (forward and reverse).

2. COMPRESSOR DRIVEN SHAFT (High Speed)

a. Forward and reverse high speed thrust bearing.

b. Two journal bearings.

3. SPEED INCREASING GEARS

a. Meshing surfaces of drive and pinion gear teeth.

To provide the required amount of oil under the neces-

sary pressure to properly lubricate these parts, a mo-

tor driven submersible oil pump is located in a remote

oil sump.

Upon pressing of the COMPRESSOR START switch

on the Control Center, the oil pump is immediately en-

ergized. After a 50 second delay to allow the system

oil pressure to stabilize, the compressor motor will start.

The oil pump will continue to run during the entire op-

eration of the compressor, and for 150 seconds during

compressor coastdown.

The submerged oil pump takes suction from the sur-

rounding oil and discharges it to the oil cooler where

heat is rejected. The oil flows from the oil cooler to the

oil filter. The oil leaves the filter and flows to the emer-

gency oil reservoir where it is distributed to the com-

pressor bearings. The oil lubricates the compressor

rotating components and is returned to the oil sump.

Since the emergency oil reservoir is at the highest

point in the lubrication system, it provides an oil sup-

ply to the various bearings and gears in the event of a

system shutdown due to power failure. The reservoir,

located on the top of the compressor, allows the oil to

be distributed through the passages by gravity flow,

thus providing necessary lubrication during the com-

pressor coastdown.

OIL PUMP

For normal operation, the oil pump should operate at

all times during chiller operation. Manual pump opera-

tion may be used to establish stable oil pressure be-

fore starting. When depressed and released, the

MANUAL OIL PUMP key will operate the oil pump for

10 minutes and then automatically shut off. To stop the

YORK INTERNATIONAL 39

FORM 160.49-O2

FIG. 18 – SCHEMATIC DRAWING – (YK) COMPRESSOR LUBRICATION SYSTEM LD00951

40 YORK INTERNATIONAL

oil pump sooner, depress the MANUAL OIL PUMP key

again.

On shutdown of the system for any reason, the oil pump

operates and continues to run for 150 seconds. The

system cannot restart during that time interval.

OIL HEATER

During long idle periods, the oil in the compressor oil

reservoir tends to absorb as much refrigerant as it can

hold, depending upon the temperature of the oil and

the pressure in the reservoir. As the oil temperature is

lowered, the amount of refrigerant absorbed will be in-

creased. If the quantity of refrigerant in the oil becomes

excessive, violent oil foaming will result as the pres-

sure within the system is lowered on starting. This foam-

ing is caused by refrigerant boiling out of the oil as the

pressure is lowered. If this foam reaches the oil pump

suction, the bearing oil pressure will fluctuate with pos-

sible temporary loss of lubrication, causing the oil pres-

sure safety cutout to actuate and stop the system. See

“Control Center, Section 2”.

To maintain the lowest possible concentration of re-

frigerant in the oil, the compressor oil reservoir is

equipped with a 115 volt electric reservoir oil heater.

The oil heater is thermostatically controlled at all times

during compressor shutdown to maintain the sump oil

at 145°F to 155°F. If the oil temperature falls below

55°F, the display will read

SYSTEM SHUTDOWN – PRESS STATUS

.

Pressing the STATUS key causes the message to read

DAY 10:00 AM – LOW OIL TEMP – AUTO START

. The system

will be allowed to automatically restart when oil tem-

perature rises to 30°F above condenser temperature.

MOTOR DRIVELINE

The compressor motor is an open-drip-proof, squirrel

cage, induction type constructed to YORK design speci-

fications. 60 hertz motors operate at 3570 rpm. 50 hertz

motors operate at 2975 rpm.

(For 60 hertz motors 1750 HP and smaller; and 50

hertz motors 1400 HP and smaller) . . . the open motor

is provided with a D-flange, factory mounted to a cast

iron adapter mounted on the compressor.

(For 2000 HP 60 hertz motors; and 50 hertz motors

above 1400 HP) . . . a separate structural steel base is

furnished to provide rigid mounting of the compressor

and motor, independent of the evaporator shell, to en-

sure controlled alignment of the assembly. Motor is

mounted with final alignment at start-up.

Motor drive shaft is directly connected to the com-

pressor shaft with a flexible disc coupling. Coupling

has all metal construction with no wearing parts to

assure long life, and no lubrication requirements to pro-

vide low maintenance.

For units utilizing remote electro-mechanical starters,

a terminal box is provided for field connected conduit.

Motor terminals are brought through the motor casing

into the terminal box. Jumpers are furnished for three-

lead type of starting. Motor terminal lugs are not fur-

nished. Overload/overcurrent transformers are fur-

nished with all units. For units furnished with factory

packaged Solid State Starters, (optional) see right.

HEAT EXCHANGERS

Evaporator and condenser shells are fabricated from

rolled carbon steel plates with fusion welded seams.

Heat exchanger tubes are internally enhanced type.

The evaporator is a shell and tube, flooded type heat

exchanger. A distributor trough provides uniform distri-

bution of refrigerant over the entire shell length. Alumi-

num mesh eliminators are located above the tube bundle

to prevent liquid refrigerant carryover into the com-

pressor. Two 1-1/2" liquid level sight glasses are lo-

cated on the side of the shell to aid in determining

proper refrigerant charge. The evaporator shell con-

tains a dual refrigerant relief valve.

The condenser is a shell and tube type, with a dis-

charge gas baffle to prevent direct high velocity im-

pingement on the tubes. A separate subcooler is lo-

cated in the condenser.

The removable compact water boxes are fabricated of

steel. The design working pressure is 150 psig and the

boxes are tested at 225 psig. Integral steel water baffles

provide the required pass arrangements. Stub-out wa-

ter nozzle connections with Victaulic grooves are

welded to the water boxes. These nozzle connections

are suitable for Victaulic couplings, welding or flanges,

and are capped for shipment. Plugged 3/4" drain and

vent connections are provided in each water box.

REFRIGERANT FLOW CONTROL

Refrigerant flow to the evaporator is controlled by a

single fixed-orifice (or variable orifice).

Chillers can be provided with a REFRIGERANT LEVEL

CONTROL (EPROM version C.02.F(T).13 or later sup-

ports this feature). A level sensor senses the refriger-

ant level in the condenser and outputs an analog volt-

YORK INTERNATIONAL 41

FORM 160.49-O2

age to the Micro Board that represents this level (0% =

empty; 100% = full). Under program control, the Micro

Board modulates a variable orifice to control the con-

denser refrigerant level to a programmed setpoint. Other

setpoints affect the control sensitivity and response.

These setpoints must be entered at chiller commis-

sioning by a qualified service technician. Only a quali-

fied service technician may modify these settings.

Manual operation of the refrigerant level control can be

selected. This allows the prerotation vanes keypad keys

to manually control the variable orifice. This manual

control can also be used to position the variable orifice

in a fixed position. Instructions for selecting manual

level control and entering the level control setpoints

are contained in the “Special Setpoints and Program-

ming Procedures” section of Service manual, Form

160.49-M3.

While the chiller is shut down, the orifice will be in the

fully open position causing the sensed level to be ap-

proximately 0%. When the chiller is started, after the

vane motor end switch (VMS) opens when entering

“SYSTEM RUN”, if actual level is less than the level

setpoint, a linearly increasing ramp is applied to the

level setpoint. This ramp causes the setpoint to go from

the initial refrigerant level (approximately 0%) to the

programmed setpoint over a period of 15 minutes. While

this ramp is in effect,

PULLDN LEVEL = XXX%; SETP = XXX%; ACTUAL = XXX%

is

one of the scrolled messages under the DISPLAY DATA

key. “PULLDN LEVEL” is the ramping setpoint that will

ramp up to the programmed setpoint “SETP”. “SETP”

is the level setpoint programmed by the service tech-

nician. “ACTUAL” is the present refrigerant level in the

condenser. After the 15 minute pulldown period has

elapsed, this message is replaced by

ACTUAL LEVEL = XXX%; LEVEL SETP = XXX%

.

If the actual level is greater than the setpoint when the

VMS opens, there is no pulldown period, it immedi-

ately begins to control to the programmed setpoint.

While the chiller is running, the refrigerant level is nor-

mally controlled to the level setpoint. However, any-

time the vanes fully close (VMS closes), normal level

control is terminated, any refrigerant level setpoint

pulldown in effect is cancelled and the outputs to the

level control will be opposite that which is supplied to

the vane motor (i.e., when a close pulse is applied to

the vane motor, an open pulse is applied to the level

control, etc.). When the VMS opens, if the refrigerant

level is less than the level setpoint, a refrigerant level

setpoint pulldown is initiated as described above. Oth-

erwise, the level is controlled to the programmed

setpoint.

If the refrigerant level sensor output ever goes to greater

than 4.4VDC, indicating a level greater than 100%,

WARNING-REFRIGERANT LEVEL OUT OF RANGE

is dis-

played and the level control actuator is driven open

until the level has decreased to a level within range.

When within range, the warning message is automati-

cally cleared and normal control is resumed.

MICROCOMPUTER CONTROL CENTER

(See Section 2)

The MicroComputer Control Center is factory mounted,

wired and tested. The electronic panel automatically

controls the operation of the unit in meeting system

cooling requirements while minimizing energy usage.

For detailed information on the Control Center, refer to

“Section 2” of this manual.

SOLID STATE STARTER (Optional)

The Solid State Starter is a reduced voltage starter

that controls and maintains a constant current flow to

the motor during start-up. It is mounted on the chiller.

Power and control wiring between the starter and chiller

are factory installed. Available for 380-600 volts, the

starter enclosure is NEMA-1 with a hinged access door

with lock and key. Electrical lugs for incoming power

wiring are provided.

VARIABLE SPEED DRIVE (Optional)

A 460V – 3-Ph – 60/50Hz Variable Speed Drive can be

factory packaged with the chiller. It is designed to vary

the compressor motor speed and prerotation vane po-

sition by controlling the frequency and voltage of the

electrical power to the motor. Operational information

is contained in Form 160.00-O1. The control logic au-

tomatically adjusts motor speed and compressor

prerotation vane position for maximum part load effi-

ciency by analyzing information fed to it by sensors

located throughout the chiller.

42 YORK INTERNATIONAL

SECTION 5

OPERATIONAL MAINTENANCE

OIL RETURN SYSTEM

The oil return system continuously maintains the proper

oil level in the compressor oil sump. (See Figs. 18 &

19.)

High pressure condenser gas flows continuously

through the eductor inducing the low pressure, oil rich

liquid to flow from the evaporator, through the dehydra-

tor to the compressor sump.

CHANGING THE DEHYDRATOR

To change the dehydrator, use the following procedure:

1. Shut the stop valves on the condenser gas line, oil

return line to rotor support and inlet end of the de-

hydrator.

2. Remove the dehydrator. Refer to Fig. 19.

3. Assemble the new filter-drier.

4. Open condenser stop valve and check dehydrator

connections for refrigerant leaks.

5. Open all the dehydrator stop valves to allow the

liquid refrigerant to flow through the dehydrator and

condenser-gas through the eductor.

FIG. 19 – OIL RETURN SYSTEM

LD00950

YORK INTERNATIONAL 43

FORM 160.49-O2

THE OIL CHARGE

The nominal oil charge for the compressor is 20 gal.,

type “F” for R-22 application or type “K” for R-134a

application.

New YORK Refrigeration oil must be used in the cen-

trifugal compressor. Since oil absorbs moisture when

exposed to the atmosphere, it should be kept tightly

capped until used.

OIL CHARGING PROCEDURE

The oil should be charged into the oil reservoir using

the YORK Oil Charging Pump – YORK Part No. 070-

10654. To charge oil into the oil reservoir, proceed as

follows:

1. The unit must be shut down.

2. Immerse the suction connection of the oil charging

pump in a clean container of new oil and connect

the pump discharge connection to the oil charging

valve (A) located on the remote oil reservoir cover

plate. (See Fig. 20.) Do not tighten the connection

at the charging valve until after the air is forced out

by pumping a few strokes of the oil pump. This fills

the lines with oil and prevents air from being pumped

into the system.

3. Open the oil charging valve and pump oil into the

system until oil level in the compressor oil reser-

voir is about midway in the upper sight glass. Then,

close the charging valve and disconnect the hand

oil pump.

4. As soon as oil charging is complete, close the power

supply to the starter to energize the oil heater. (See

“Section 3, System Operating Procedures”.) This

will keep the concentration of refrigerant in the oil

to a minimum.

When the oil reservoir is initially charged with oil, the

oil pump should be started manually to fill the lines,

passages, oil cooler and oil filter. This will lower the oil

level in the reservoir. It will then be necessary to add

oil to bring the level back to the center of the upper

sight glass.

FIG. 20 – CHARGING OIL RESERVOIR WITH OIL

LD00472

OIL CHARGING

VALVE

25721A

44 YORK INTERNATIONAL

SECTION 6

TROUBLESHOOTING

TABLE 1 – CAUSES OF NORMAL AND SAFETY SYSTEM SHUTDOWNS IN ACCORDANCE WITH THE MICROCOMPUTER CONTROL,

CENTER DISPLAY

SHUTDOWN CAUSE GOVERNING CONTROL FUNCTION

CONTROL CENTER DISPLAY

OPERATING PROGRAMMED START-UP OF PROBABLE CAUSE

DAY OF TIME OF CAUSE OF METHOD OF DESCRIPTION POINT SETPOINTS SYSTEM AFTER AND SERVICE

WEEK DAY SHUTDOWN RESTART ON ON BY OPERATOR SHUTDOWN REQUIRED

RISE FALL

MON. 10:00 AM Low Water Autostart Low Water Chilled 4°F below 4°F below chilled Automatic Restart System load is less

Temp. (LWT) water chiller water setpoint when water reaches than minimum

setpoint water (If set to 40°F setpoint; if system capacity

setpoint would be 36°F) is running and set-

(36°F minimum point is increased

4°F, system will

continue to run, as

LWT cutout shifts

to a fixed 36°F for

10 minutes.

MON. 10:00 AM Flow Switch Autostart Flow Switch Automatic Restart Lack of water flow.

when water flow is Check operation of

Restored to close chilled water pump

flow switch.

MON. 10:00 AM System Autostart A remote com- Automatic Restart Contact-connected to

Cycling mand (computer upon remote the Remote/Local

relay contact or command. cycling input of the

manual switch) Digital input board

MON. 10:00 AM Multi-Unit Autostart (Optional) Lead- Automatic Restart Contact-connected to

Lag Sequence upon remote the Multi-Unit cycling

Control command. input of the Digital

input board

MON. 10:00 AM Internal Autostart Internal Clock Daily Schedule Will automatically Pressing Compressor

Clock Programmed to restart when pro- Start Switch over-

Shutdown Unit grammed schedule rides the program

permits

MON. 10:00 AM AC under- Autostart <15% FLA for Cycling shutdown oc-

voltage 25 continuous curs when motor cur-

seconds rent is >15% FLA for

25 seconds during

chiller operation

MON. 10:00 AM Power Fault Autostart CM-2 Current Will start automatic- Motor Controller con-

Module or tically following tacts opening and

Solid State coastdown closing in less than 3

Starter seconds due to a power

fault condition

Remote Stop Energy manage- Start up by start Remote Stop Contact

ment System signal from remote Closure

start switch

MON. Anti-Recycle, Anti-Recycle Will not start Will restart when Min. Time between

20 Min. Left timer until 30 Min. time left = 00 Min. successive compres-

timer is timed sor starts is 30 min.

YORK INTERNATIONAL 45

FORM 160.49-O2

MON. 10:00 AM Low Evap. Low Evap. 54.3 54.4 To restart, press See OPERATION

Pressure Pressure

PSIG (R-22) PSIG (R-22)

compressor switch ANALYSIS Table 2

Transducer 25 25.1 from STOP/RESET Symptom 2

(LEP)

PSIG (R-134a) PSIG (R-134a)

to START position

MON. 10:00 AM Low Evap. LEP external Set to Job Set to Job To restart, press See OPERATION

Pressure control (Brine Spec. Spec. compressor switch ANALYSIS Table 2

Brine units only) from STOP/RESET Symptom 2.

to START position

MON. 10:00 AM Low Oil Low Oil 25 15 Will restart when Refer to OPERATION

Pressure Pressure PSID PSID pressure increases ANALYSIS Table 2

Transducer to 25 PSID. To Symptoms 4, 5, 6, 7,

(OP) restart, press com- 9, 10, 11

pressor switch from

STOP/RESTART to

START position.

MON. 10:00 AM High High Pressure 265 205 Will restart when See Operational

Pressure Safety Control

PSIG (R-22) PSIG (R-22)

Pressure falls to Analysis Table 2

(HP) 180 120 205 PSIG. To restart Symptom 1 High

PSIG (R-134a) PSIG (R-134a)

press compressor Discharge Pressure

switch from STOP/

RESET to START

position

MON. 10:00 AM Evap. Trans. Evap. Pressure To restart press Defective Evap. Pressure

or Probe Transducer or compressor switch Transducer or Leaving

Error Leaving Chilled from STOP/RESET Chilled Water thermistor

Water Thermis- to START position (RS1). LCWT minus satu-

tor (RS1) ration temperature is less

than –2.5°F or greater than

25°F. Checked every 10

minutes following a 10 min.

bypass at start-up.

MON. 10:00 AM Motor Con- CM2 or Solid Reset the device CM2, or Solid State

troller – Ext. State Starter that caused the shut- Starter has shutdown

Reset (RT2) down. Chiller will chiller

start automatically.

MON. 10:00 AM High Discharge Temp. 220°F 219°F To restart press Condenser tubes dirty or

Discharge Thermistor compressor switch scaled or high condenser

Temp. (RT2) from STOP/RESET water temperature. (See

to START position. Symptom 1, Table 1.)

MON. 10:00 AM High Oil Oil Temperature 170°F 169°F To restart press Dirty oil filter or restricted

Temp. Thermistor compressor switch oil cooler line. Change oil

(RT3) from STOP/RESET filter. Refer to OPERATION

to START position ANALYSIS Table 2,

Symptom 9.

MON. 10:00 AM Power Auto-Restart Micro Board 8.29VDC 7.84VDC Optional AUTO Will restart automa- Power Failure.

Failure undervoltage Restart Plug is tically when voltage

circuit on 5V installed on reaches 8.29VDC.

unregulated Micro Board An undervoltage

supply circuit on the Micro

Board monitors the

5VC unregulated

supply for an under-

voltage condition.

MON. 10:00 AM Power Micro Board 8.29VDC 7.84VDC Auto restart plug To restart, press Power Failure

Failure undervoltage is removed on compressor switch

circuit on 5V Micro Board to STOP-RESET

unregulated Position and then to

supply START position (Continued on page 46)

46 YORK INTERNATIONAL

TABLE 1 – CAUSES OF NORMAL AND SAFETY SYSTEM SHUTDOWNS IN ACCORDANCE WITH THE MICROCOMPUTER CONTROL,

CENTER DISPLAY

SHUTDOWN CAUSE GOVERNING CONTROL FUNCTION

CONTROL CENTER DISPLAY

OPERATING PROGRAMMED START-UP OF PROBABLE CAUSE

DAY OF TIME OF CAUSE OF METHOD OF DESCRIPTION POINT SETPOINTS SYSTEM AFTER AND SERVICE

WEEK DAY SHUTDOWN RESTART ON ON BY OPERATOR SHUTDOWN REQUIRED

RISE FALL

MON. 10:00 AM Oil Pressure High Oil Press. 100 PSID (Dur- 59 Will start at 59 This Shutdown is provided

Transducer Transducer ing first 7 min. of PSID PSID when compr. to check on Oil Pressure

Error Compr. Oper.) switch is placed to Transducers for failure in

60 PSID (After STOP/RESET and the high state. Replace

first 7 min. of then START Oil Press. Transducer in

Compr. Oper.) oil sump or compressor

Vane Motor Autostart Vane Motor Restart automatically Vanes are set improperly,

Switch Open Switch after Vane Motor arm reset vane linkage check

linkage is set pro- vane positions using

perly. Press STOP/ the SERVICE key switch

RESET and then and proper keys on the

START switch MicroComputer Control

Center

MON. 10:00 AM Starter Motor Current > Press compressor Check motor starter

Malfunction 15% for 10 swc. STOP/RESET operation. Motor current

Detected with Control Cen- switch and then value greater than 15%

ter not calling for FLA

motor to run

MON. 10:00 AM Program Autostart Micro Board Watchdog timer circuit

Initiated has reset software pro-

Reset gram – Chiller will

automatically restart.

Replace RTC RTC-IC chip Reprogram the Con- Weak battery

IC chip trol Center Setponts Replace RTC-IC chip

Reprogram & proceed with U16

Setpoints Normal Start-up

MON. 10:00 AM Low Oil Autostart Oil Temp. 71.0°F 55°F Press STOP/ Oil Temp. Thermistor

Temperature Thermistor RESET switch & disconnected from

(RT3) then START Analog Input Board.

switch Reconnect or replace

open sensor.

MON. 10:00 AM Faulty Dis- Discharge Temp. 30.0°F 29.9°F Press STOP/ Faulty Discharge Temp.

charge Temp. Thermistor START switch & Thermistor (RT2) or dis-

Sensor (RT2) discon- then START connected from Analog

nected or faulty switch Input Board. Connect or

operating temp. replace open sensor.

= 32°F

MON. 100.00 AM Low Line SSS Logic See legend on wiring Chiller will automa- Low AC Line Voltage

Voltage (SSS Board diagram tically restart when

Units only) all phases of line vol-

tage increase to the

minimum required

starting level.

MON. 10:00 AM MTR Phase SSS Logic See “Section 2” Press STOP/START Motor Phase Current

Current Board switch then START Unbalance

unbalance switch

(SSS Units

only)

YORK INTERNATIONAL 47

FORM 160.49-O2

TABLE 2 – OPERATING ANALYSIS CHART

RESULTS POSSIBLE CAUSE REMEDY

1. SYMPTOM: ABNORMALLY HIGH DISCHARGE PRESSURE

Temperature difference between liquid Air in condenser.

refrigerant out and water off condenser

higher than normal.

High discharge pressure. Condenser tubes dirty or . Clean condenser tubes. Check water

scaled conditioning.

High condenser water Reduce condenser water inlet

temperature. temperature. (Check cooling tower

and water circulation.)

Temperature difference between conden- Insufficient condensing Increase the quantity of water through

ser water on and water off higher than water flow. the condenser to proper value.

normal, with normal cooler pressure.

2. SYMPTOM: ABNORMALLY LOW SUCTION PRESSURE

Temperature difference between leaving Insufficient charge of Check for leaks and charge

chilled water and refrigerant in cooler refrigerant. refrigerant into system.

greater than normal with high discharge Flow orifice blocked. Remove obstruction.

temperature.

Temperature difference between leaving Cooler tubes dirty or Clean cooler tubes.

chilled water and refrigerant in the cooler restricted.

greater than normal with normal discharge

temperature.

Temperature of chilled water too low with Insufficient load for Check prerotation vane motor opera-

with low motor amperes. system capacity. tion and setting of low water temper-

ature cutout.

3. SYMPTOM: HIGH COOLER PRESSURE

High chilled water temperature. Prerotation vanes fail to Check the prerotation vane motor

open. positioning circuit.

System overload. Be sure the vanes are wide open

(without overloading the motor) until

the load decreases.

4. SYMPTOM: NO OIL PRESSURE WHEN SYSTEM START BUTTON PUSHED

Low oil pressure displayed on control Oil pump running in wrong Check rotation of oil pump

center; compressor will not start. direction. (Electrical Connections).

Oil pump not running. Check electrical connections to oil

pump and press manual reset on oil

pump starter mounted on condenser

shell.

5. SYMPTOM: COMPRESSOR STARTS, NORMAL OIL PRESSURE DEVELOPS, FLUCTUATES FOR

SHORT WHILE, THEN COMPRESSOR STOPS ON OIL PRESSURE CUTOUT

Oil pressure normal, fluctuates then Unusual starting conditions Drain the oil from the compressor and

compressor stops on Oil Pressure exist, i.e., oil foaming in charge new oil into the compressor.

Cutout. Display reading resevoir and piping due to (Refer to “Charging The System With

LOW OIL PRESSURE .

lowered system pressure. Oil”, page 39.)

Burned out oil heater. Replace oil heater.

48 YORK INTERNATIONAL

TABLE 2 – OPERATING ANALYSIS CHART (Continued)

RESULTS POSSIBLE CAUSE REMEDY

6. SYMPTOM: USUALLY HIGH OIL PRESSURE DEVELOPS WHEN OIL PUMP RUNS

Unusually high oil pressure is displayed High oil pressure. Trans- Replace low or high oil pressure

when the oil pressure display key is ducer defective. Relief transducer. Adjust external relief

pressed when the oil pump is running. valve is misadjusted. valve.

7. SYMPTOM: OIL PUMP VIBRATES OR IS NOISY

Oil pump vibrates or is extremely noisy Misalignment of pump or Correct condition or replace faulty

with some oil pressure when pressing Mounting bolts loose. part.

OIL PRESSURE display key. Bent shaft.

Worn pump parts.

NOTE: When oil pump is run without Oil not reaching pump Check oil supply and oil piping.

an oil supply it will vibrate and suction inlet in sufficient

become extremely noisy. quantity.

8. SYMPTOM: OIL PRESSURE GRADUALLY DECREASES (Noted by Observation of Daily Log Sheets)

Oil pressure (noted when pressing OIL Oil filter is dirty. Change oil filter.

PRESSURE display key) drops to 70%

of oil pressure when compressor was Extreme bearing wear. Inspect compressor.

originally started.

9. SYMPTOM: OIL PRESSURE SYSTEM CEASES TO RETURN AN OIL/REFRIGERANT SAMPLE

Oil refrigerant return not functioning. Filter-drier in oil return Replace old filter-drier with new.

system dirty.

Jet or orifice of oil return Remove jet, inspect for dirt. Remove

jet clogged. dirt using solvent and replace.

10. SYMPTOM: OIL PUMP FAILS TO DELIVER OIL PRESSURE

No oil pressure registers when pressing Faulty oil pressure Replace oil pressure transducer.

OIL PRESSURE display key when oil transducer

pump runs. Faulty wiring/connectors.

11. SYMPTOM: REDUCED OIL PUMP CAPACITY

Oil pump pumping capacity. Excessive end clearance Inspect and replace worn parts.

pump.

Other worn pump parts.

Partially blocked oil supply Check oil inlet for blockage.

inlet.

YORK INTERNATIONAL 49

FORM 160.49-O2

SECTION 7

MAINTENANCE

RENEWAL PARTS

For any required Renewal Parts, refer to “Parts Lists”

shown in “Reference Instructions”, page 2.

CHECKING SYSTEM FOR LEAKS

LEAK TESTING DURING OPERATION

The refrigerant side of the system is carefully pres-

sure tested and evacuated at the factory.

After the system is in operation under load, the high

pressure components should be carefully leak tested

with a leak detector to be sure all joints are tight.

If any leaks are indicated, they must be repaired im-

mediately. Usually, leaks can be stopped by tightening

flare nuts or flange bolts. However, if it is necessary to

repair a welded joint, the refrigerant charge must be

removed. (See “Handling Refrigerant for Dismantling

and Repair”, page 53.)

CONDUCTING R-22 PRESSURE TEST

With the R-22 charge removed and all known leaks

repaired, the system should be charged with a small

amount of R-22 mixed with dry nitrogen so that a ha-

lide torch or electronic leak detector can be used to

detect any leaks too small to be found by the soap

test.

To test with R-22, proceed as follows:

1. With no pressure in the system, charge R-22 gas

into the system through the charging valve to a

pressure of 2 psig.

2. Build up the system pressure with dry nitrogen to

approximately 10 psig. To be sure that the concen-

tration of refrigerant has reached all part of the sys-

tem, slightly open the oil charging valve and test

for the presence of refrigerant with a leak detector.

3. Test around each joint and factory weld. It is impor-

tant that this test be thoroughly and carefully done,

spending as much time as necessary and using a

good leak detector.

4. To check for refrigerant leaks in the cooler and con-

denser, open the vents in the cooler and condenser

heads and test for the presence of refrigerant. If no

refrigerant is present, the tubes and tube sheets

may be considered tight. If refrigerant is detected

at the vents, the heads must be removed, the leak

located (by means of soap test or leak detector)

and repaired.

EVACUATION AND DEHYDRATION OF UNIT

FIG. 21 – EVACUATION OF CHILLER

27385A(D)

LD00949

50 YORK INTERNATIONAL

VACUUM TESTING

After the pressure test has been completed, the vacuum

test should be conducted as follows:

1. Connect a high capacity vacuum pump, with indi-

cator, to the system charging valve as shown in

Fig. 22 and start the pump. (See “Vacuum Dehydra-

tion”.)

2. Open wide all system valves, including the purge

and gauge valves. Be sure all valves to the atmo-

sphere are closed.

3. Operate the vacuum pump in accordance with

VACUUM DEHYDRATION until a wet bulb tempera-

ture of +32°F or a pressure of 5 mm Hg is reached.

See Table 3 for corresponding values of pressure.

4. To improve evacuation circulate hot water (not to

exceed 125°F) through the cooler and condenser

tubes to thoroughly dehydrate the shells. If a source

of hot water is not readily available, a portable wa-

ter heater should be employed. DO NOT USE

STEAM. A suggested method is to connect a hose

between the source of hot water under pressure

and the cooler head drain connection, out the cooler

vent connection, into the condenser head drain and

out the condenser vent. To avoid the possibility of

causing leaks, the temperature should be brought

up slowly so that the tubes and shell are heated

evenly.

5. Close the system charging valve and the stop valve

between the vacuum indicator and the vacuum

pump. Then disconnect the vacuum pump leaving

the vacuum indicator in place.

6. Hold the vacuum obtained in Step 3 in the system

for 8 hours; the slightest rise in pressure indicates

a leak or the presence of moisture, or both. If, after

8 hours the wet bulb temperature in the vacuum

indicator has not risen above 40°F or a pressure of

6.3 mm Hg, the system may be considered tight.

NOTE: Be sure the vacuum indicator is valved off

while holding the system vacuum and be

sure to open the valve between the vacuum

indicator and the system when checking

the vacuum after the 8 hour period.

7. If the vacuum does not hold for 8 hours within the

limits specified in Step 6 above, the leak must be

found and repaired.

TABLE 3 – SYSTEM PRESSURES

*GAUGE ABSOLUTE BOILING

INCHES OF TEMPERATURES

MERCURY (HG) MILLIMETERS OF

BELOW ONE PSIA OF MERCURY MICRONS WATER

STANDARD (HG) °F

ATMOSPHERE

0 14.696 760. 760,000 212

10.24" 9.629 500. 500,000 192

22.05" 3.865 200. 200,000 151

25.98" 1.935 100. 100,000 124

27.95" .968 50. 50,000 101

28.94" .481 25. 25,000 78

29.53" .192 10. 10,000 52

29.67" .122 6.3 6,300 40

29.72" .099 5. 5,000 35

29.842" .039 2. 2,000 15

29.882" .019 1.0 1,000 +1

29.901" .010 .5 500 –11

29.917" .002 .1 100 –38

29.919" .001 .05 50 –50

29.9206" .0002 .01 10 –70

29.921" 0 0 0

*One standard atmosphere = 14.696 PSIA

= 760 mm Hg. absolute pressure at 32°F

= 29.921 inches Hg. absolute at 32°F

NOTES: PSIA = Lbs. per sq. in. gauge pressure

= Pressure above atmosphere

PSIA = Lbs. per sq. in. absolute pressure

= Sum of gauge plus atmospheric pressure

YORK INTERNATIONAL 51

FORM 160.49-O2

VACUUM DEHYDRATION

To obtain a sufficiently dry system, the following in-

structions have been assembled to provide an effec-

tive method for evacuating and dehydrating a system

in the field. Although there are several methods of de-

hydrating a system, we are recommending the follow-

ing, as it produces one of the best results, and affords

a means of obtaining accurate readings as to the ex-

tent of dehydration.

The equipment required to follow this method of dehy-

dration consists of a wet bulb indicator or vacuum

gauge, a chart showing the relation between dew point

temperature and pressure in inches of mercury

(vacuum), (see Table 3) and a vacuum pump capable

of pumping a suitable vacuum on the system.

OPERATION

Dehydration of a refrigerant system can be obtained

by this method because the water present in the sys-

tem reacts much as a refrigerant would. By pulling down

the pressure in the system to a point where its satura-

tion temperature is considerably below that of room

temperature, heat will flow from the room through the

walls of the system and vaporize the water, allowing a

large percentage of it to be removed by the vacuum

pump. The length of time necessary for the dehydra-

tion of a system is dependent on the size or volume of

the system, the capacity and efficiency of the vacuum

pump, the room temperature and the quantity of water

present in the system. By the use of the vacuum indi-

cator as suggested, the test tube will be evacuated to

the same pressure as the system, and the distilled

water will be maintained at the same saturation tem-

perature as any free water in the system, and this tem-

perature can be observed on the thermometer.

If the system has been pressure tested and found to

be tight prior to evacuation, then the saturation tem-

perature recordings should follow a curve similar to

the typical saturation curve shown as Fig. 22.

The temperature of the water in the test tube will drop

as the pressure decreases, until the boiling point is

reached, at which point the temperature will level off

and remain at this level until all of the water in the shell

is vaporized. When this final vaporization has taken

place the pressure and temperature will continue to

drop until eventually a temperature of 35°F or a pres-

sure of 5 mm Hg. is reached.

When this point is reached, practically all of the air

has been evacuated from the system, but there is still

a small amount of moisture left. In order to provide a

medium for carrying this residual moisture to the

vacuum pump, nitrogen should be introduced into the

system to bring it to atmospheric pressure and the

indicator temperature will return to approximately am-

bient temperature. Close off the system again, and start

the second evacuation.

The relatively small amount of moisture left will be car-

ried out through the vacuum pump and the tempera-

ture or pressure shown by the indicator should drop

uniformly until it reaches a temperature of 35°F or a

pressure of 5 mm Hg.

When the vacuum indicator registers this temperature

or pressure, it is a positive sign that the system is

evacuated and dehydrated to the recommended limit.

If this level cannot be reached, it is evident that there

is a leak somewhere in the system. Any leaks must be

corrected before the indicator can be pulled down to

35°F or 5 mm Hg. in the primary evacuation.

During the primary pulldown, keep a careful watch on

the wet bulb indicator temperature, and do not let it fall

below 35°F. If the temperature is allowed to fall to 32°F,

the water in the test tube will freeze, and the result will

be a faulty temperature reading.

FIG. 22 – SATURATION CURVE

LD00474

52 YORK INTERNATIONAL

REFRIGERANT CHARGING

To avoid the possibility if freezing liquid within the

cooler tubes when charging an evacuated sys-

tem, only refrigerant vapor from the top of the

drum or cylinder must be admitted to the system

pressure until the system pressure is raised above

the point corresponding to the freezing point of

the cooler liquid. For water, the pressure corre-

sponding to the freezing point is 57.5 PSIG for R-

22 or 8.54 PSIG for R-134a (at sea level).

While charging, every precaution must be taken

to prevent moisture laden air from entering the

system. Make up a suitable charging connection

from new copper tubing to fit between the system

charging valve and the fitting on the charging drum.

This connection should be as short as possible

but long enough to permit sufficient flexibility for

changing drums. The charging connection should

be purged each time a full container of refrigerant

is connected and changing containers should be

done as quickly as possible to minimize the loss

of refrigerant.

Refrigerant may be furnished in drums containing

either 30, 50, 125 or 1750 lbs. of refrigerant. These

drums are not returnable and they should be

stored for future use if it should ever become nec-

essary to remove refrigeration from the system.

TABLE 4 – REFRIGERANT CHARGE

R-22

SHELL CODES LBS.

COOLER COND.

M M 1,425

M N 1,600

N M 1,675

N N 1,800

N P 1,800

P N 1,875

P P 1,875

P Q 2,175

Q P 2,225

Q Q 2,500

Q R 2,800

R Q 3,050

R R 3,300

R S 3,500

S R 3,500

S S 3,500

R-134a

SHELL CODES LBS.

COOLER COND.

L L 1,150

L M 1,150

M L 1,400

M M 1,400

M N 1,585

N M 1,650

N N 1,805

N P 1,805

P N 1,900

P P 1,900

P Q 2,205

Q P 2,235

Q Q 2,515

Q R 2,800

R Q 3,075

R R 3,325

R S 3,450

S R 3,450

S S 3,575

CHECKING THE REFRIGERANT CHARGE

DURING UNIT SHUTDOWN

The refrigerant charge is specified for each chiller model

(see Table 4). Charge the correct amount of refrigerant

and record the level in the cooler sight glass.

The refrigerant charge should always be checked and

trimmed when the system is shut down.

The refrigerant charge level must be checked after the

pressure and temperature have equalized between the

condenser and cooler. This would be expected to be 4

hours or more after the compressor and water pumps

are stopped. The level should be at the center of the

sight glass + 1/4 inch.

Charge the refrigerant in accordance with the method

shown under the “Refrigerant Charging”, above. The

refrigerant level should be observed and the level re-

corded after initial charging.

YORK INTERNATIONAL 53

FORM 160.49-O2

HANDLING REFRIGERANT FOR

DISMANTLING AND REPAIRS

MEGGING THE MOTOR

If it becomes necessary to open any part of the refriger-

ant system for repairs, it will be necessary to remove the

charge before opening any part of the unit.

While the main disconnect switch and compressor

motor starter are open, meg the motor as follows:

1. Using a megohm meter (megger), meg between

phases and each phase to ground (see Fig. 23);

these readings are to be interpreted using the graph

shown in Fig. 24.

2. If readings fall below shaded area, remove external

leads from motor and repeat test.

NOTE: Motor is to be megged with the starter at

ambient temperature after 24 hours of idle

standby.

FIG. 23 – DIAGRAM, MEGGING MOTOR WINDINGS

LD00475

54 YORK INTERNATIONAL

FIG. 24 – MOTOR STATOR TEMPERATURE AND INSULATION RESISTANCES

LD00476

TEMPERATURE – °F

MEGOHMS

Minimum Insulation Resistance vs. Temperature (per IEEE Std 43)

Open Motors

YORK INTERNATIONAL 55

FORM 160.49-O2

CONDENSERS AND COOLERS

GENERAL

Maintenance of condenser and cooler shells is impor-

tant to provide trouble free operation of the chiller. The

water side of the tubes in the shell must be kept clean

and free from scale. Proper maintenance such as tube

cleaning, and testing for leaks, is covered on the fol-

lowing pages.

CHEMICAL WATER TREATMENT

Since the mineral content of the water circulated

through coolers and condensers varies with almost

every source of supply, it is possible that the water

being used may corrode the tubes or deposit heat re-

sistant scale in them. Reliable water treatment compa-

nies are available in most larger cities to supply a wa-

ter treating process which will greatly reduce the cor-

rosive and scale forming properties of almost any type

of water.

As a preventive measure against scale and corrosion

and to prolong the life of cooler and condenser tubes, a

chemical analysis of the water should be made prefer-

ably before the system is installed. A reliable water

treatment company can be consulted to determine

whether water treatment is necessary, and if so, to

furnish the proper treatment for the particular water

condition.

CLEANING COOLER AND CONDENSER TUBES

COOLER

It is difficult to determine by any particular test whether

possible lack of performance of the water cooler is due

to fouled tubes alone or due to a combination of

troubles. Trouble which may be due to fouled tubes is

indicated when, over a period of time, the cooling ca-

pacity decreases and the split (temperature difference

between water leaving the cooler and the refrigerant

temperature in the cooler) increases. A gradual drop-

off in cooling capacity can also be caused by a gradual

leak of refrigerant from the system or by a combina-

tion of fouled tubes and shortage of refrigerant charge.

An excessive quantity of oil in the cooler can also con-

tribute to erratic performance.

CONDENSER

In a condenser, trouble due to fouled tubes is usually

indicated by a steady rise in head pressure, over a

period of time, accompanied by a steady rise in con-

densing temperature, and noisy operation. These symp-

toms may also be due to foul gas buildup. Purging will

remove the foul gas revealing the effect of fouling.

TUBE FOULING

Fouling of the tubes can be due to deposits of two

types as follows:

1. Rust or sludge – which finds its way into the tubes

and accumulates there. This material usually does

not build up on the inner tube surfaces as scale,

but does interfere with the heat transfer. Rust or

sludge can generally be removed from the tubes by

a thorough brushing process.

2. Scale – due to mineral deposits. These deposits,

even though very thin and scarcely detectable upon

physical inspection, are highly resistant to heat

transfer. They can be removed most effectively by

circulating an acid solution through the tubes.

TUBE CLEANING PROCEDURES

BRUSH CLEANING OF TUBES

If the tube consists of dirt and sludge, it can usually be

removed by means of the brushing process. Drain the

water sides of the circuit to be cleaned (cooling water

or chilled water) remove the heads and thoroughly clean

each tube with a soft bristle bronze brush. DO NOT

USE A STEEL BRISTLE BRUSH. A steel brush may

damage the tubes.

Improved results can be obtained by admitting water

into the tube during the cleaning process. This can be

done by mounting the brush on a suitable length of 1/8"

pipe with a few small holes at the brush end and con-

necting the other end by means of a hose to the water

supply.

The tubes should always be brush cleaned before acid

cleaning.

ACID CLEANING OF TUBES

If the tubes are fouled with a hard scale deposit, they

must be acid cleaned. It is important that before acid

cleaning, the tubes be cleaned by the brushing pro-

cess described above. If the relatively loose foreign

material is removed before the acid cleaning, the acid

solution will have less material to dissolve and flush

from the tubes with the result that a more satisfactory

cleaning job will be accomplished with a probable sav-

ing of time.

COMMERCIAL ACID CLEANING

In many major cities, commercial organizations now

offer a specialized service of acid cleaning coolers

and condensers. If acid cleaning is required, YORK

56 YORK INTERNATIONAL

recommends the use of this type of organization. The

Dow Industries Service Division of the Dow Chemical

Company, Tulsa, Oklahoma, with branches in principal

cities is one of the most reliable of these companies.

TESTING FOR COOLER AND CONDENSER

TUBE LEAKS

Cooler and condenser tube leaks in R-22 or R-134a

systems may result in refrigerant leaking into the wa-

ter circuit, or water leaking into the shell depending on

the pressure levels. If refrigerant is leaking into the

water, it can be detected at the liquid head vents after

a period of shutdown. If water is leaking into the refrig-

erant, system capacity and efficiency will drop off

sharply. If a tube is leaking and water has entered the

system, the cooler and condenser should be valved

off from the rest of the water circuit and drained imme-

diately to prevent severe rusting and corrosion. If a

tube leak is indicated, the exact location of the leak

may be determined as follows:

1. Remove the heads and listen at each section of

tubes for a hissing sound that would indicate gas

leakage. This will assist in locating the section of

tubes to be further investigated. If the probable lo-

cation of the leaky tubes has been determined, treat

that section in the following manner (if the location

is not definite, all the tubes will require investiga-

tions).

2. Wash off both tube heads and the ends of all tubes

with water.

NOTE: Do not use carbon tetrachloride for this pur-

pose since its fumes give the same flame

discoloration that the refrigerant does.

3. With nitrogen or dry air, blow out the tubes to clear

them of traces of refrigerant laden moisture from

the circulation water. As soon as the tubes are clear,

a cork should be driven into each end of the tube.

Repeat this with all of the other tubes in the sus-

pected section or if necessary, with all the tubes in

the cooler or condenser. Allow the cooler or con-

denser to remain corked up to 12 to 24 hours be-

fore proceeding. Depending upon the amount of leak-

age, the corks may blow from the end of a tube,

indicating the location of the leakage. If not, if will

be necessary to make a very thorough test with

the leak detector.

4. After the tubes have been corked for 12 to 24 hours,

it is recommended that two men working at both

ends of the cooler carefully test each tube – one

man removing corks at one end and the other at

the opposite end to remove corks and handle the

leak detector. Start with the top row of tubes in the

section being investigated, remove the corks at the

ends of one tube simultaneously and insert the ex-

ploring tube for 5 seconds – this should be long

enough to draw into the detector any refrigerant

gas that might have leaked through the tube walls.

A fan placed at the end of the cooler opposite the

detector will assure that any leakage will travel

through the tube to the detector.

5. Mark any leaking tubes for later identification.

6. If any of the tube sheet joints are leaking, the leak

should be indicated by the detector. If a tube sheet

leak is suspected, its exact location may be found

by using a soap solution. A continuous buildup of

bubbles around a tube indicates a tube sheet leak.

YORK INTERNATIONAL 57

FORM 160.49-O2

COMPRESSOR

ELECTRICAL CONTROLS

Maintenance for the compressor assembly consists of

checking the operation of the oil return system and

changing the dehydrator, checking and changing the

oil, checking and changing the oil filters, checking the

operation of the oil heater, checking the operation of

the oil pump, and observing the operation of the com-

pressor.

Internal wearing of compressor parts could be a seri-

ous problem caused by improper lubrication, brought

about by restricted oil lines, passages, or dirty oil fil-

ters. If the unit is shutting down on (HOT) High Oil

Temperature or Low Oil Pressure (OP), change the oil

filter element. Examine the oil filter element for the pres-

ence of aluminum particles. If aluminum particles are

noticeable and the same conditions continue to stop

the unit operation after a new filter element is installed,

notify the nearest YORK office to request the presence

of a YORK Service man.

For information covering the MicroComputer Control

Center operation, refer to “Section 2”.

The operating points of the pressure and temperature

cut outs are shown in the Wiring Diagrams. These

diagrams also contain a starting and stopping

sequence diagram.

58 YORK INTERNATIONAL

SECTION 8

PREVENTIVE MAINTENANCE

It is the responsibility of the owner to provide the nec-

essary daily, monthy and yearly maintenance require-

ments of the system.

IMPORTANT – If a unit failure

occurs due to improper maintenance during the war-

ranty period; YORK will not be liable for costs incurred

to return the system to satisfactory operation.

In any operating system it is most important to provide

a planned maintenance and inspection of its function-

ing parts to keep it operating at its peak efficiency.

Therefore, the following maintenance should be per-

formed when prescribed.

COMPRESSOR

1. Oil Filter – The oil filter must be changed when the

oil pressure drops 30% or semi-annually if not re-

quired earlier.

When the oil filter is changed, it should be inspected

thoroughly for any aluminum particles which would

indicate possible bearing wear. If aluminum particles

are found this should be brought to the attention of

the nearest YORK office for their further investiga-

tion and recommendations.

2. Oil Changing – The oil in the compressor must be

changed annually or earlier if it becomes dark or

cloudy.

COMPRESSOR MOTOR

1. Check motor mounting screws frequently to insure

tightness.

2. Meg motor windings annually to check for deterio-

ration of windings.

PRESSURE TESTING

The unit should be pressure tested annually. Any leaks

found must be repaired immediately. Air and moisture

are the worst enemies of these systems and experi-

ence has shown that units which are maintained tight,

are systems that provide trouble free efficient opera-

tion.

COOLER AND CONDENSER

The major portion of maintenance on the condenser

and cooler will deal with the maintaining the water side

of the condenser and cooler in a clean condition.

The use of untreated water in cooling towers, closed

water systems, etc. frequently results in one or more

of the following:

1. Scale Formation.

2. Corrosion or Rusting.

3. Slime and Algae Formation.

It is therefore to the benefit of the user to provide for

proper water treatment to provide for a longer and more

economical life of the equipment. The following recom-

mendation should be followed in determining the con-

dition of the water side of the condenser and cooler

tubes.

1. The condenser tubes should be cleaned annually

or earlier if conditions warrant. If the temperature

difference between the water off the condenser and

the condenser liquid temperature is more than 4°

greater than the difference recorded on a new unit,

it is a good indication that the condenser tubes re-

quire cleaning. They should be cleaned as instructed

on pages 38 to 39 of this manual.

2. The cooler tubes under normal circumstances will

not require cleaning. If however the temperature dif-

ference between the refrigerant and the chilled wa-

ter increases slowly over the operating season, it

is an indication that the cooler tubes may be fouling

or that there may be a water by-pass in the water

box requiring gasket relacement or refrigerant may

have leaked from the chiller.

OIL RETURN SYSTEM

1. Change the dehydrator in the oil return system semi-

annually or earlier if the oil return system fails to

operate.

2. When the dehydrator is changed, the nozzle of the

YORK INTERNATIONAL 59

FORM 160.49-O2

eductor should be checked for any foreign particles

that may be obstructing the jet.

ELECTRICAL CONTROLS

1. All electrical controls should be inspected for obvi-

ous malfunctions.

2. It is important that the factory settings of controls

(operation and safety) not be changed. If the set-

tings are changed without YORK’s approval, the

warranty will be jeopardized.

3. A 5-11 year life battery is part of the RTC-Real

Time Clock. To replace, refer to page 29.

P.O. Box 1592, York, Pennsylvania USA 17405-1592 Subject to change without notice. Printed in USA

Copyright © by York International Corporation 1997 ALL RIGHTS RESERVED

Form 160.49-O2 (1296)

Supersedes: Nothing