Carrier 25HCR 2si User Manual To The 0ed6864e A73a 4822 969e F1a1950130c2

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25HCR
COMFORTt SERIES R---22 HEAT PUMPS
SIZES 18 TO 60
1---1/2 TO 5 NOMINAL TONS

Installation Instructions
TABLE OF CONTENTS
PAGE
SAFETY CONSIDERATIONS . . . . . . . . . . . . . . . . . . . . . . . 2
INSTALLATION RECOMMENDATIONS . . . . . . . . . . . . . 2
INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 -- 10
Step 1 -- Check Equipment & Jobsite . . . . . . . . . . . . . . . 3
Step 2 -- Install on Solid Pad . . . . . . . . . . . . . . . . . . . . . . 3
Step 3 -- Clearance Requirements . . . . . . . . . . . . . . . . . . 3
Step 4 -- Operating Ambient . . . . . . . . . . . . . . . . . . . . . . 3
Step 5 -- Install TXV . . . . . . . . . . . . . . . . . . . . . . . . . 3 -- 4
Step 6 -- Check Defrost Thermostat . . . . . . . . . . . . . . . . . 4
Step 7 -- Make Piping Connections . . . . . . . . . . . . . . 4 -- 6
Step 8 -- Make Electrical Connections . . . . . . . . . . . . 6 -- 7
Step 9 -- Compressor Crankcase Heater . . . . . . . . . . . . . 7
Step 10 -- Install Electrical Accessories . . . . . . . . . . . . . . 7
Step 11 -- Start--Up . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 -- 9
Step 12 -- Check Charge . . . . . . . . . . . . . . . . . . . . . . . . . 10
Step 13 -- Final Checks . . . . . . . . . . . . . . . . . . . . . . . . . . 10
CARE AND MAINTENANCE . . . . . . . . . . . . . . . . . . . . . . 10

Fig. 1 --- 25HCR

A05341

NOTE: Read the entire instruction manual before starting the
installation.

INSTALLATION RECOMMENDATIONS
NOTE: In some cases noise in the living area has been traced to
gas pulsations from improper installation of equipment.
1. Locate unit away from windows, patios, decks, etc. where
unit operation sound may disturb customer.
2. Ensure that vapor and liquid tube diameters are
appropriate for unit capacity.
3. Run refrigerant tubes as directly as possible by avoiding
unnecessary turns and bends.
4. Leave some slack between structure and unit to absorb
vibration.
5. When passing refrigerant tubes through the wall, seal
opening with RTV or other pliable silicon--based caulk.
(See Fig. 2.)
6. Avoid direct tubing contact with water pipes, duct work,
floor joists, wall studs, floors, and walls.
7. Do not suspend refrigerant tubing from joists and studs
with a rigid wire or strap which comes in direct contact
with tubing.(See Fig. 2.)
8. Ensure that tubing insulation is pliable and completely
surrounds vapor tube.
9. When necessary, use hanger straps which are 1 in. wide
and conform to shape of tubing insulation. (See Fig. 2.)
10. Isolate hanger straps from insulation by using metal
sleeves bent to conform to shape of insulation.

25HCR

SAFETY CONSIDERATIONS
Improper
installation,
adjustment,
alteration,
service,
maintenance, or use can cause explosion, fire, electrical shock, or
other conditions which may cause death, personal injury, or
property damage. Consult a qualified installer, service agency, or
your distributor or branch for information or assistance. The
qualified installer or agency must use factory--authorized kits or
accessories when modifying this product. Refer to the individual
instructions packaged with the kits or accessories when installing.
Follow all safety codes. Wear safety glasses, protective clothing,
and work gloves. Use quenching cloth for brazing operations.
Have fire extinguisher available. Read these instructions
thoroughly and follow all warnings or cautions included in
literature and attached to the unit. Consult local building codes
and National Electrical Code (NEC) for special requirements.
Recognize safety information. This is the safety--alert symbol ! .
When you see this symbol on the unit and in instructions or
manuals, be alert to the potential for personal injury.
Understand these signal words; DANGER, WARNING, and
CAUTION. These words are used with the safety--alert symbol.
DANGER identifies the most serious hazards which will result in
severe personal injury or death. WARNING signifies hazards
which could result in personal injury or death. CAUTION is used
to identify unsafe practices which may result in minor personal
injury or product and property damage. NOTE is used to
highlight suggestions which will result in enhanced installation,
reliability, or operation.

NOTE: Avoid contact between tubing and structure

WARNING

OUTDOOR WALL

INDOOR WALL

CAULK

LIQUID TUBE

ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal
injury or death.

VAPOR TUBE

Before installing, modifying, or servicing system, main
electrical disconnect switch must be in the OFF
position. There may be more than 1 disconnect switch.
Lock out and tag switch with a suitable warning label.

INSULATION
THROUGH THE WALL
JOIST
HANGER STRAP
(AROUND VAPOR
TUBE ONLY)

INSULATION
VAPOR TUBE

1″ MIN.
LIQUID TUBE
SUSPENSION

Fig. 2 --- Connecting Tubing Installation

A94028

When outdoor unit is connected to factory--approved indoor unit,
outdoor unit contains system refrigerant charge for operation with
ARI rated indoor unit when connected by 15 ft. of field--supplied
or factory accessory tubing. For proper unit operation, check
refrigerant charge using charging information located on control
box cover and/or in the Check Charge section of this instruction.
IMPORTANT: Maximum liquid--line size is 3/8--in. OD for all
residential applications including line line.
IMPORTANT: Always install the factory--supplied liquid--line
filter drier. Obtain replacement filter driers from your distributor
or branch.

INSTALLATION
STEP 1 —Check Equipment and Job Site
Unpack Unit
Move to final location. Remove carton taking care not to damage
unit.
Inspect Equipment
File claim with shipping company prior to installation if shipment
is damaged or incomplete. Locate unit rating plate on unit corner
panel. It contains information needed to properly install unit.
Check rating plate to be sure unit matches job specifications.
STEP 2 —Install on a Solid, Level Mounting Pad
If conditions or local codes require the unit be attached to pad, tie
down bolts should be used and fastened through knockouts
provided in unit base pan. Refer to unit mounting pattern in Fig.
3 to determine base pan size and knockout hole location.
For hurricane tie downs, contact distributor for details and PE
Certification (Professional Engineer), if required.
On rooftop applications, mount on level platform or frame. Place
unit above a load--bearing wall and isolate unit and tubing set
from structure. Arrange supporting members to adequately
support unit and minimize transmission of vibration to building.
Consult local codes governing rooftop applications.
Roof mounted units exposed to winds above 5 mph may require
wind baffles. Consult the Service Manual -- Residential Split
System Air Conditioners and Heat Pumps for wind baffle
construction.
NOTE: Unit must be level to within ±2° (±3/8 in./ft.) per
compressor manufacturer specifications.
STEP 3 —Clearance Requirements
When installing, allow sufficient space for airflow clearance,
wiring, refrigerant piping, and service. Allow 30--in. clearance to
service end of unit and 48 in. above unit. For proper airflow, a
6--in. clearance on 1 side of unit and 12 in. on all remaining sides
must be maintained. Maintain a distance of 24 in. between units.
Position so water, snow, or ice from roof or eaves cannot fall
directly on unit.

On rooftop applications, locate unit at least 6 in. above roof
surface.
STEP 4 —Operating Ambient
The minimum outdoor operating ambient in cooling mode is
55°F, and the maximum outdoor operating ambient in cooling
mode is 125°F. The maximum outdoor operating ambient in
heating mode is 66 °F.
STEP 5 —Install TXV
NOTE: Applies to non--TXV indoor units only. If installing a
rated and approved indoor coil without a factory installed R--22
TXV, remove and replace the fixed orifice or PuronR TXV
expansion device with an R--22 TXV.

CAUTION

Failure to follow this caution may result in equipment damage
or improper operation.
All indoor coil units must be installed with a hard shut off
R--22 TXV metering device.
IMPORTANT: If not factory installed, the TXV should be
mounted as close to the indoor coil as possible and in a vertical,
upright position. Avoid mounting the inlet tube vertically down.
Valve is more susceptible to malfunction due to debris if inlet
tube is facing down. A factory--approved filter drier must be
installed in the liquid line.
Installing TXV in Place of Piston
1. Pump system down to 2 psig and recover refrigerant.
2. Remove hex nut from piston body. Use backup wrench on
fan coils.
3. Remove and discard factory--installed piston. Be sure
Teflon seal is in place.
4. Reinstall hex nut. Finger tighten nut plus 1/2 turn.
NOTE: If the piston is not removed from the body, TXV will
not function properly.

3/8 ---in. Dia. Tiedown
Knockouts in Basepan
(2) Places

CAUTION

EQUIPMENT DAMAGE HAZARD
Failure to follow this caution may result in equipment
damage or improper operation.
Use a brazing shield and wrap TXV with wet cloth or
use heat sink material.
5. Install TXV on indoor coil liquid line. Sweat swivel
adapter to inlet of indoor coil and attach to TXV outlet.
Use backup wrench to avoid damage to tubing or valve.
Sweat inlet of TXV, marked “IN” to liquid line. Avoid
excessive heat which could damage valve.
6. Install vapor elbow with equalizer adapter to suction tube
of line set and suction connection to indoor coil. Adapter
has a 1/4--in. male connector for attaching equalizer tube.
7. Connect equalizer tube of TXV to 1/4--in. equalizer fitting
on vapor line adapter.
8. Attach TXV bulb to horizontal section of suction line
using clamps provided. Insulate bulb with field--supplied
insulation tape. See Fig. 4 for correct positioning of
sensing bulb.
9. Proceed with remainder of unit installation.

View From Top

UNIT BASE PAN
DIMENSIONS

TIEDOWN KNOCKOUT LOCATIONS
A

26 X 26

9–1/8

4–7/16

21–1/4

31–1/2 X 31–1/2

9–1/8

6–9/16

24–11/16

35 X 35

9–1/8

6–9/16

28–7/16

Fig. 3 --- Clearance Requirements

A05177

25HCR

UNIT OPERATION HAZARD

STEP 6 —Check Defrost Thermostat
Check defrost thermostat to ensure it is properly located and
securely attached. There is a liquid header with a brass distributor
and feeder tube going into outdoor coil. At the end of the one of
the feeder tubes, there is a 3/8 in. O.D. stub tube approximately 2
in. long. (See Fig. 5.) The defrost thermostat should be located on
stub tube. Note that there is only one stub tube used with liquid
header, and on most units it is the bottom circuit.

10 O'CLOCK
2 O'CLOCK
SENSING BULB
STRAP

SUCTION TUBE
8 O'CLOCK
7⁄
8

IN. OD & SMALLER

FEEDER TUBE

4 O'CLOCK
LARGER THAN

25HCR

Fig. 4 --- Position of Sensing Bulb

7⁄8

STUB TUBE

IN. OD
A81032

Replacing TXV on Puron Indoor Coil
1. Pump system down to 2 psig and recover refrigerant.
2. Remove coil access panel and fitting panel from front of
cabinet.
3. Remove TXV support clamp using a 5/16--in. nut driver.
Save the clamp.
4. Remove Puron TXV using a backup wrench on flare
connections to prevent damage to tubing.
5. Using wire cutters, cut equalizer tube off flush with vapor
tube inside cabinet.
6. Remove bulb from vapor tube inside cabinet.
7. Braze equalizer stub--tube closed. Use protective barrier as
necessary to prevent damage to drain pan.
IMPORTANT: Route the equalizer tube of R--22 TXV through
suction line connection opening in fitting panel prior to replacing
fitting panel around tubing.
8. Install TXV with 3/8--in. copper tubing through small hole
in service panel. Use wrench and backup wrench, to avoid
damage to tubing or valve, to attach TXV to distributor.
9. Reinstall TXV support clamp (removed in item 3).
10. Attach TXV bulb to vapor tube inside cabinet, in same
location as original was when removed, using supplied
bulb clamps (nylon or copper). See Fig. 4 for correct
positioning of sensing bulb.
11. Route equalizer tube through suction connection opening
(large hole) in fitting panel and install fitting panel in
place.
12. Sweat inlet of TXV, marked IN to liquid line. Avoid
excessive heat which could damage valve.
13. Install vapor elbow with equalizer adapter to vapor line of
line set and vapor connection to indoor coil. Adapter has
a 1/4--in. male connector for attaching equalizer tube.
14. Connect equalizer tube of TXV to 1/4--in. equalizer fitting
on vapor line adapter. Use backup wrench to prevent
damage to equalizer fitting.
15. Proceed with remainder of unit installation.

DEFROST
THERMOSTAT

Fig. 5 --- Defrost Thermostat Location

A97517

STEP 7 —Make Piping Connections

WARNING

PERSONAL INJURY AND ENVIRONMENTAL
HAZARD
Failure to follow this warning could result in personal
injury or death.
Relieve pressure and recover all refrigerant before
system repair or final unit disposal. Use all service
ports and open all flow--control devices, including
solenoid valves.

CAUTION

UNIT DAMAGE HAZARD
Failure to follow this caution may result in equipment
damage or improper operation.
If ANY refrigerant tubing is buried, provide a 6--in. vertical
rise at service valve. Refrigerant tubing lengths up to 36--in.
may be buried without further special consideration. Do not
bury lines longer than 36 in.

CAUTION

UNIT DAMAGE HAZARD
Failure to follow this caution may result in equipment
damage or improper operation.
To prevent damage to unit or service valves, observe the
following:
S Use a brazing shield
S Wrap service valves with wet cloth or use a heat sink
material.

Remove plastic retainer holding outdoor piston in liquid service
valve, leaving the piston and piston retainer inside the valve.
Connect sweat/flare adapter provided, to valve. (See Fig. 6.)
Connect refrigerant tubing to fittings on outdoor unit vapor and
liquid service valves. Service valves are closed from factory and
ready for brazing. After wrapping service valve with a wet cloth,
tubing set can be brazed to service valve using either silver
bearing or non--silver bearing brazing material. Do not use soft
solder (materials which melt below 800°F). Consult local code
requirements. Refrigerant tubing and indoor coil are now ready
for leak testing. This check should include all field and factory
joints.

Outdoor units may be connected to indoor section using
accessory tubing package or field--supplied refrigerant grade
tubing of correct size and condition. For tubing requirements
beyond 80 ft., substantial capacity and performance losses can
occur. Following the recommendations in the Application
Guideline and Service Manual--Residential Split--System Air
Conditioners and Heat Pumps will reduce these losses. Refer to
Table 1 for accessory requirements. Refer to Table 2 for field
tubing diameters.
There are no buried--line applications greater than 36 in.
If refrigerant tubes or indoor coil are exposed to atmosphere, they
must be evacuated to 500 microns to eliminate contamination and
moisture in the system.
Outdoor Unit Connected to Factory--Approved Indoor Unit
Outdoor unit contains correct system refrigerant charge for
operation with approved ARI rated indoor unit when connected
by 15 ft. of field--supplied or factory--accessory tubing, and
factory supplied filter drier. Check refrigerant charge for
maximum efficiency.
Refrigerant Tubing and Sweat Connections
Connect vapor tube to fitting on outdoor unit vapor service
valves (see Table 2). Connect liquid tubing to adapter tube on
liquid service valve. Use refrigerant grade tubing.

25HCR

PISTON BODY

PISTON
PISTON
RETAINER

CAUTION

SWEAT/FLARE ADAPTER

UNIT DAMAGE HAZARD
Failure to follow this caution may result in equipment
damage or improper operation.

Fig. 6 --- Liquid Service Valve

Service valves must be wrapped in a heat--sinking
material such as a wet cloth while brazing.

A05226

Table 1—Accessory Usage

Crankcase Heater

REQUIRED FOR LOW---AMBIENT APPLICATIONS
(Below 55 °F)
Yes

Evaporator Freeze Thermostat

Yes

Winter Start Control

Yes

Accessory

REQUIRED FOR LONG LINE APPLICATIONS* (Over 80 ft.)
Yes

Accumulator

Compressor Start Assist Capacitor and Relay

Yes

Support Feet

Recommended

No
No
No
Yes
No

Liquid Line Solenoid Valve

See Long --- Line Application Guideline

* For Tubing Set lengths between 80 and 200 ft. horizontal or 20 ft. vertical differential (250 ft. Total Equivalent Length), refer to the Long Line Guidelines for Air
Conditioners and Heat Pumps using R---22.

Table 2—Refrigerant Connections and Recommended Liquid and Vapor Tube Diameters (in.)
UNIT SIZE
018, 024
030, 036
042, 048
060

LIQUID

VAPOR (up to 80 ft.*)

Connection Diameter

Tube
Diameter

Connection Diameter

Rated Tube Diameter

3/8
3/8
3/8
3/8

5/8
3/4
7/8
7/8

5/8
3/4
7/8
1-- 1/8

Notes:
1. Tube diameters are for total equivalent lengths up to 80 ft..
2. Do not apply capillary tube or fixed orifice indoor coils to these units.
* For Tubing Set lengths between 80 and 200 ft. horizontal or 20 ft. vertical differential (250 ft.Total Equivalent Length), refer to the Longline Guideline --- Air
Conditioners and Heat Pumps using R---22

STEP 8 —Make Electrical Connections

IMPORTANT: Check to be certain factory tubing on both
indoor and outdoor unit has not shifted during shipment. Ensure
tubes are not rubbing against each other or any sheet metal. Pay
close attention to feeder tubes, makings sure wire ties on feeder
tubes are secure and tight.
Be sure field wiring complies with local and national fire, safety,
and electrical codes, and voltage to system is within limits shown
on unit rating plate. Contact local power company for correction
of improper voltage. See unit rating plate for recommended
circuit protection device.
NOTE: Operation of unit on improper line voltage constitutes
abuse and could affect unit reliability. See unit rating plate. Do
not install unit in system where voltage may fluctuate above or
below permissible limits.

25HCR

WARNING

ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal
injury or death.
Do not supply power to unit with compressor terminal
box cover removed.
NOTE: Use copper wire only between disconnect switch and
unit.
NOTE: Install branch circuit disconnect of adequate size per
NEC to handle unit starting current. Locate disconnect within
sight from and readily accessible from unit, per Section 440--14
of NEC.
Route Ground and Power Wires
Remove access panel to gain access to unit wiring. Extend wires
from disconnect through power wiring hole provided and into
unit control box.
Connect Ground and Power Wires
Connect ground wire to ground connection in control box for
safety. Connect power wiring to contactor as shown in Fig. 8.

CAUTION

UNIT DAMAGE HAZARD
Failure to follow this caution may result in equipment
damage or improper operation.
Installation of filter drier in liquid line is required.
Install Liquid Line Filter Drier Indoor
Refer to Fig. 7 and install filter drier as follows:
1. Braze 5 in. liquid tube to the indoor coil.
2. Wrap filter drier with damp cloth.
3. Braze filter drier to 5 in. long liquid tube from step 1.
4. Connect and braze liquid refrigerant tube to the filter drier.

WARNING

ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal
injury or death.
The unit cabinet must have an uninterrupted or unbroken
ground to minimize personal injury if an electrical fault
should occur. The ground may consist of electrical wire or
metal conduit when installed in accordance with existing
electrical codes.
Connect ground wire to ground connection in control box for
safety. Connect power wiring to contactor as shown in Fig. 8.
DISCONNECT
PER N. E. C. AND/OR
LOCAL CODES
CONTACTOR
FIELD POWER
WIRING

Fig. 7 --- Liquid Line Filter Drier

FIELD GROUND

A05227

WIRING

GROUND
LUG

Fig. 8 --- Line Connections

A94025

STEP 11 —Start--Up

Connect Control Wiring
Route 24v control wires through control wiring grommet and
connect leads to control wiring. See Thermostat Installation
Instructions for wiring specific unit combinations. (See Fig. 9.)
Use No. 18 AWG color--coded, insulated (35°C minimum) wire.
If thermostat is located more than 100 ft. from unit, as measured
along the control voltage wires, use No. 16 AWG color--coded
wire to avoid excessive voltage drop.
All wiring must be NEC Class 1 and must be separated from
incoming power leads.
Use furnace transformer, fan coil transformer, or accessory
transformer for control power, 24v/40va minimum.
NOTE: Use of available 24v accessories may exceed the
minimum 40va power requirement. Determine total transformer
loading and increase the transformer capacity or split the load
with an accessory transformer as required.
Final Wiring Check
IMPORTANT: Check factory wiring and field wire connections
to ensure terminations are secured properly. Check wire routing
to ensure wires are not in contact with tubing, sheet metal, etc.
STEP 9 —Compressor Crankcase Heater
When equipped with a crankcase heater, furnish power to heater a
minimum of 24 hr before starting unit. To furnish power to heater
only, set thermostat to OFF and close electrical disconnect to
outdoor unit.
A crankcase heater is required if refrigerant tubing is longer than
80 ft. Refer to the Long Line Guideline--Residential Split--System
Air Conditioners and Heat Pumps.
STEP 10 —Install Electrical Accessories
Refer to the individual instructions packaged with kits or
accessories when installing.

CAUTION

PERSONAL INJURY HAZARD
Failure to follow this caution may result in personal
injury.
Wear safety glasses, protective clothing, and gloves when
handling refrigerant and observe the following:
S Front seating service valves are equipped with Schrader
valves.

CAUTION

ENVIRONMENTAL HAZARD
Failure to follow this caution may result in environmental
damage.
Federal regulations require that you do not vent refrigerant to
the atmosphere. Recover during system repair or final unit
disposal.

CAUTION

UNIT OPERATION AND SAFETY HAZARD
Failure to follow this caution may result in minor personal
injury, equipment damage or improper operation.
To prevent compressor damage or personal injury,
observe the following:
S Do not overcharge system with refrigerant.
S Do not operate unit in a vacuum or at negative pressure.
S Do not disable low pressure switch in scroll compressor
applications.
S Dome temperatures may be hot.
Follow these steps to properly start up system:
1. After system is evacuated, fully open liquid and vapor
service valves.
2. Unit is shipped with valve stem(s) front seated (closed)
and caps installed. Replace stem caps after system is
opened to refrigerant flow (back seated). Replace caps
finger--tight and tighten with wrench an additional 1/12
turn.
3. Close electrical disconnects to energize system.
4. Set room thermostat at desired temperature. Be sure set
point is below indoor ambient temperature.
5. Set room thermostat to HEAT or COOL and fan control to
ON or AUTO mode, as desired. Operate unit for 15
minutes. Check system refrigerant charge.

25HCR

HP THERMOSTAT

24 VAC HOT

24 VAC COM

W2 *

HEAT STAGE 2

25HCR

HEAT
PUMP

TYPICAL
FAN COIL

COOL/HEAT
STAGE 1

INDOOR FAN

RVS COOLING

EMERGENCY
HEAT

W3 *
G

* IF AVAILABLE

LEGEND
24-V FACTORY WIRING
24-V FIELD WIRING
FIELD SPLICE CONNECTION
ODT

OUTDOOR THERMOSTAT
EHR

EMERGENCY HEAT RELAY

SHR

SUPPLEMENTAL HEAT RELAY

A02325 / A97413

Fig. 9 --- Generic Wiring Diagrams
(See Thermostat Installation Instructions for specific unit combinations)

OF1

DFT

OF2

T2 C C O
T1
Y

O R W2 Y C

P1
30

120

DFT

QUIET
SHIFT

90
INTERVAL TIMER OFF

SPEEDUP

Speedup
Pins

HK32EA003
Quiet
Shift

Defrost interval
DIP switches

Fig. 10 --- Defrost Control

A05378

Quiet Shift
Quiet shift is a field selectable defrost mode (factory set to OFF),
which will eliminate occasional noise that could be heard at the
start of defrost cycle and restarting of heating cycle. It is selected
by placing DIP switch 3 on defrost board (see Fig. 12) in the ON
position.
When Quiet Shift switch is placed in ON position, and a defrost is
initiated, the following sequence of operation will occur.
Reversing valve will energize, compressor will turn off for 30
seconds, and then turn back on to complete defrost. At the start of
heating after conclusion of defrost, reversing valve will
de--energize, compressor will turn off for another 30 seconds, and
the fan will turn off for 40 seconds, before starting in the heating
mode.
Defrost
The defrost control is a time/temperature control which has field
selectable settings of 30, 60, 90, or 120 minutes, factory set to
90 minutes. These settings represent the amount of time that must
pass after closure of the defrost thermostat before the defrost
sequence begins.
The defrost thermostat senses coil temperature throughout the
heating cycle. When the coil temperature reaches the defrost
thermostat setting of approximately 32 degrees F, it will close,
which energizes the DFT terminal and begins the defrost timing
sequence. When the DFT has been energized for the selected
time, the defrost cycle begins.
Defrost cycle is terminated when defrost thermostat opens, or
automatically after 10 minutes.
Defrost Speedup
To initiate a forced defrost, speedup pins (J1) must be shorted
with a flat head screwdriver for 5 seconds and RELEASED. If
the defrost thermostat is open, a short defrost cycle will be
observed (actual length depends on Quiet Shift switch position).
When Quiet Shift is off, only a short 30 second defrost cycle is
observed. With Quiet Shift ON, the speedup sequence is one
minute; 30 second compressor off period followed by 30 seconds
of defrost with compressor operation. When returning to heating
mode, the compressor will turn off for an additional 30 seconds
and the fan for 40 seconds.
If the defrost thermostat is closed, a complete defrost cycle is
initiated. If the Quiet Shift switch is turned on, the compressor
will be turned off for two 30 second intervals as explained
previously.

NOTE: If the indoor blower off delay is enabled, it will run up
to an additional 90 seconds to increase system efficiency.
Heating
On a call for heating, thermostat makes circuits R--Y and R--G.
Circuit R--Y sends low voltage through the safeties and energizes
the T1 terminal on the circuit board. T1 energizes the defrost
logic circuit. If the compressor has been off for 5 minutes, or
power
has not been cycled for 5 minutes, the OF2 relay and T2 terminal
will energize. This will close the contactor, start the outdoor fan
motor and compressor.
When the cycle is complete, R--Y is turned off , stopping the
compressor and outdoor fan. The 5 minute time guard begins
counting. Compressor will not come on again until this time
delay expires. In the event of a power interruption, the time guard
will
not allow another cycle for 5 minutes.

25HCR

Sequence of Operation
NOTE: Defrost control board is equipped with 5 minute lockout
timer that is initiated upon any interruption of power.
Turn on power to indoor and outdoor units. Transformer is
energized.
Cooling
On a call for cooling, thermostat makes circuits R--O, R--Y, and
R--G. Circuit R--O energizes reversing valve, switching it to
cooling position. Circuit R--Y sends low voltage through the
safeties and energizes the T1 terminal on the circuit board. If the
compressor
has been off for 5 minutes, or power has not been cycled for 5
minutes, the OF2 relay and T2 terminal will energize. This will
close the contactor, and start the outdoor fan motor and
compressor.
When the cycle is complete, R--Y is turned off, stopping the
compressor and outdoor fan. The 5 minute time guard begins
counting. Compressor will not come on again until this delay
expires. In the event of a power interruption, the time guard will
not allow another cycle for 5 minutes.

25HCR

STEP 12 —Check Charge
Factory charge and charging method are shown on unit rating
plate. To check charge in cooling mode, refer to Cooling Only
Procedure. To check charge in heating mode, refer to Heating
Check Chart Procedure.
Cooling Only Procedure
NOTE: If subcooling charging conditions are not favorable,
charge must be weighed in accordance with unit rating plate,
±0.6 oz./ft. of 3/8--in. liquid line above or below 15 ft.,
respectively. Favorable conditions fall within the ranges given on
the charging chart on the outdoor unit plate.
This system requires charging by the subcooling method.
1. Operate unit a minimum of 10 minutes before checking
charge.
2. Measure liquid service valve pressure by attaching an
accurate gage to service port.
3. Measure liquid line temperature by attaching an accurate
thermistor type or electronic thermometer to liquid line
near outdoor coil.
4. Refer to unit rating plate for required subcooling
temperature.
5. Refer to Table 3. Find the point where required subcooling
temperature intersects measured liquid service valve
pressure.
6. To obtain required subcooling temperature at a specific
liquid line pressure, add refrigerant if liquid line
temperature is higher than indicated or reclaim refrigerant
if temperature is lower. Allow a tolerance of ± 3°F.
Heating Check Chart Procedure
To check system operation during heating cycle, refer to the
Heating Check Chart on outdoor unit. This chart indicates
whether a correct relationship exists between system operating
pressure and air temperature entering indoor and outdoor units. If
pressure and temperature do not match on chart, system
refrigerant charge may not be correct. Do not use chart to adjust
refrigerant charge.
STEP 13 —Final Checks
IMPORTANT: Before leaving job, be sure to do the following:
1. Ensure that all wiring is routed away from tubing and
sh eet m et al ed g es t o p rev en t ru b -- t h ro u g h o r w i re
pinching.
2. Ensure that all wiring and tubing is secure in unit before
adding panels and covers. Securely fasten all panels and
covers.
3. Tighten service valve stem caps to 1/12--turn past finger
tight.
4. L eav e U sers M an u al w i t h o w n er. E x p l ai n sy st em
operation and periodic maintenance requirements outlined
in manual.
5. Fill out Dealer Installation Checklist and place in
customer file.

Table 3—Required Liquid--Line Temperature
Liquid
Pressure
at Service
Valve

Required Subcooling Temperature (°F)

(PSIG)

134

141

148

156

163

171

179

187

196

205

214

101

223

104

233

107

102

243

110

105

100

253

113

108

103

264

116

111

106

101

274

119

114

109

104

285

122

117

112

107

297

125

120

115

110

309

128

123

118

113

321

131

126

121

116

331

134

129

124

119

346

137

132

127

122

359

140

135

130

125

CARE AND MAINTENANCE
For continuing high performance and to minimize possible
equipment failure, periodic maintenance must be performed on
this equipment.
Frequency of maintenance may vary depending upon geographic
areas, such as coastal applications. See Users Manual for
information.

Printed in U.S.A.

Edition Date: 02/06

Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.

Catalog No: 25HCR-- 2SI
Replaces: 25HCR--1SI

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