Carrier 58Mxa Users Manual

58MXA to the manual ac6e789f-aa43-418d-b838-c7ee32f0cfb6

2015-01-24

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58MXA
4-Way Multipoise Fixed-Capacity
Direct-Vent Condensing Gas Furnace
Visit www.carrier.com

Service and Maintenance Instructions
→ For Sizes 040—140, Series 130

ama

®
®

•••••

U L T R A

G A S

A93040

•••••

H I G H

•••••

C Y
E F F I C I E N

C E
F U R N A N

CANADIAN GAS ASSOCIATION

A PP R O VED
R

NOTE: Read the entire instruction manual before performing any
service or maintenance.
This symbol → indicates a change since the last issue.
Index

Page

SAFETY CONSIDERATIONS..................................................1-2
ELECTROSTATIC DISCHARGE (ESD) PRECAUTIONS........2
GENERAL......................................................................................2
CARE AND MAINTENANCE................................................2-11
Cleaning and/or Replacing Air Filter.......................................3
Blower Motor and Wheel Maintenance................................3-4
Cleaning Burners ...................................................................4-5
Cleaning Heat Exchangers ....................................................5-7
Primary Heat Exchangers ................................................5-7
Secondary Heat Exchangers................................................7
Flushing Collector Box and Drainage System ........................7
Servicing Hot Surface Ignitor ...............................................7-8
Electrical Controls and Wiring.................................................8
Troubleshooting................................................................8-9-10
Checking Heat Tape Operation (If Applicable) ....................10
Winterizing ........................................................................10-11
WIRING DIAGRAM...................................................................12
SERVICE LABEL .......................................................................13
TROUBLESHOOTING GUIDE ............................................14-15
SAFETY CONSIDERATIONS
Installing and servicing heating equipment can be hazardous due to
gas and electrical components. Only trained and qualified personnel should install, repair, or service heating equipment.
Untrained personnel can perform basic maintenance functions
such as cleaning and replacing air filters. All other operations must
be performed by trained service personnel. When working on
heating equipment, observe precautions in the literature, on tags,
and on labels attached to or shipped with the unit and other safety
precautions that may apply.
Follow all safety codes. In the United States, follow all safety
codes including the National Fuel Gas Code (NFGC) NFPA
54-1996/ANSI Z223.1-1996 and the Installation Standards, Warm
Air Heating and Air Conditioning Systems (NFPA 90B)
ANSI/NFPA 90B. In Canada, refer to the CAN/CGA-B149.1- and

As an ENERGY STAR®
Partner, Carrier Corporation
has determined that this product meets the ENERGY
STAR® guidelines for energy
efficiency.

A93007

REGISTERED QUALITY SYSTEM

Fig. 1—Multipoise Furnace in Upflow Orientation
.2-M95 National Standard of Canada, Natural Gas and Propane
Installation Codes (NSCNGPIC). Wear safety glasses and work
gloves. Have a fire extinguisher available during start-up and
adjustment procedures and service calls.
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 the 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 would 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.

Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.
Book 1 4
PC 101
Catalog No. 535-745
Printed in U.S.A.
Form 58MXA-6SM
Pg 1
5-99
Replaces: 58MXA-5SM
Tab 6a 8a

GENERAL
These instructions are written as if the furnace is installed in an
upflow application. An upflow furnace application is where the
blower is located below the combustion and controls section of the
furnace, and conditioned air is discharged upward. Since this
furnace can be installed in any of the 4 positions shown in Fig. 2,
you may need to revise your orientation to component location
accordingly.

The ability to properly perform maintenance on this equipment requires certain expertise, mechanical skills, tools, and
equipment. If you do not possess these, do not attempt to
perform any maintenance on this equipment other than those
procedures recommended in the User’s Manual. FAILURE
TO FOLLOW THIS WARNING COULD RESULT IN
POSSIBLE DAMAGE TO THIS EQUIPMENT, SERIOUS
PERSONAL INJURY, OR DEATH.

AIRFLOW

Never store anything on, near, or in contact with the furnace,
such as:
1. Spray or aerosol cans, rags, brooms, dust mops, vacuum
cleaners, or other cleaning tools.
2. Soap powders, bleaches, waxes or other cleaning compounds, plastic or plastic containers, gasoline, kerosene,
cigarette lighter fluid, dry cleaning fluids, or other volatile
fluids.
3. Paint thinners and other painting compounds, paper bags,
or other paper products.
Failure to follow this warning can cause corrosion of the heat
exchanger, fire, personal injury, or death.

UPFLOW

HORIZONTAL
LEFT

HORIZONTAL
RIGHT
DOWNFLOW

AIRFLOW

ELECTROSTATIC DISCHARGE (ESD) PRECAUTIONS

A93041

Fig. 2—Multipoise Orientations
CARE AND MAINTENANCE
For continuing high performance and to minimize possible equipment failure, it is essential that maintenance be performed annually
on this equipment. Consult your local dealer for maintenance and
maintenance contract availability.

Electrostatic discharge can affect electronic components.
Take precautions during furnace installation and servicing to
protect the furnace electronic control. Precautions will prevent electrostatic discharges from personnel and hand tools
which are held during the procedure. These precautions will
help to avoid exposing the control to electrostatic discharge
by putting the furnace, the control, and the person at the same
electrostatic potential.

Turn off the gas and electrical supplies to the unit before
performing any maintenance or service. Follow the operating
instructions on the label attached to the furnace. Failure to
follow this warning could result in personal injury or death.

1. Disconnect all power to the furnace. DO NOT TOUCH THE
CONTROL OR ANY WIRE CONNECTED TO THE CONTROL PRIOR TO DISCHARGING YOUR BODY’S ELECTROSTATIC CHARGE TO GROUND.

The minimum maintenance that should be performed on this
equipment is as follows:

2. Firmly touch a clean, unpainted, metal surface of the furnace
chassis which is close to the control. Tools held in a person’s
hand during grounding will be satisfactorily discharged.

1. Check and clean or replace air filter each month as required.
2. Check blower motor and wheel for cleanliness annually.

3. After touching the chassis you may proceed to service the
control or connecting wires as long as you do nothing that
recharges your body with static electricity (for example; DO
NOT move or shuffle your feet, DO NOT touch ungrounded
objects, etc.).

3. Check electrical connections for tightness and controls for
proper operation each heating season. Service as necessary.
4. Check for proper condensate drainage. Clean as necessary.
5. Check for blockages in combustion-air and vent pipes annually.

4. If you touch ungrounded objects (recharge your body with
static electricity), firmly touch furnace again before touching
control or wires.

6. Check burners for cleanliness annually.

5. Use this procedure for installed and uninstalled (ungrounded)
furnaces.

Personal injury could result from sharp metal edges, etc. Use
care when removing parts.

6. Before removing a new control from its container, discharge
your body’s electrostatic charge to ground to protect the
control from damage. If the control is to be installed in a
furnace, follow items 1 through 5 before bringing the control
or yourself into contact with the furnace. Put all used AND
new controls into containers before touching ungrounded
objects.
7. An ESD service kit (available from commercial sources) may
also be used to prevent ESD damage.

WASHABLE
FILTER

FILTER
RETAINER

WASHABLE
FILTER

FILTER
SUPPORT

FILTER
RETAINER
A93046

A93045

Fig. 3—Bottom Filter Arrangement

Fig. 4—Filter Installed for Side Inlet

Step 1—Cleaning and/or Replacing Air Filter

All factory wires can be left connected, but field thermostat
connections may need to be disconnected depending on their
length and routing.
4. Position control box, transformer, and door switch assembly to
right side of furnace casing.

The air filter arrangement may vary depending on the application
or orientation.

5. If condensate trap is located in left- or right-hand side of
furnace casing, proceed to item 6, otherwise remove trap and
tubing as described below.

Never operate unit without a filter or with the blower access
panel removed. Failure to follow this warning could result in
a fire or personal injury.

a. Disconnect field drain connection from condensate trap.
b. Disconnect drain and relief port tubes from condensate
trap.

To clean or replace the filters, proceed as follows:
1. Turn off electrical supply to furnace.

c. Remove condensate trap from blower shelf.

2. Remove main furnace door and blower access panel.

6. Remove screws securing blower assembly to blower shelf and
slide blower assembly out of furnace.

3. Release filter retainer wire. (See Fig. 3 and 4.)
4. Slide filter out of furnace.

7. Clean blower wheel and motor by using a vacuum with soft
brush attachment. Be careful not to disturb balance weights
(clips) on blower wheel vanes. Do not bend wheel or blades as
balance will be affected.

5. Furnaces are equipped with permanent, washable filter(s).
Clean filter by spraying cold tap water through filter in
opposite direction of airflow.
6. Rinse filter and let dry. Oiling or coating of filter is not
recommended.

8. If greasy residue is present on blower wheel, remove wheel
from the blower housing and wash it with an appropriate
degreaser. To remove wheel:

7. Place filter in furnace.

a. Mark blower wheel location on shaft before disassembly to
ensure proper reassembly.

8. Replace blower access panel and main furnace door.
9. Turn on electrical supply to furnace.

b. Loosen setscrew holding blower wheel on motor shaft.
NOTE: Mark blower mounting arms and blower housing so each
arm is positioned at the same hole location during reassembly.

NOTE: If the filter has cross-mesh binding, the binding must face
the blower. If the filter has an air direction arrow, the arrow must
point toward the blower.
Step 2—Blower Motor and Wheel Maintenance

c. Mark blower wheel orientation and cutoff plate location to
ensure proper reassembly.

To ensure long life, economy, and high efficiency, clean accumulated dirt and grease from blower wheel and motor annually.

d. Remove screws securing cutoff plate and remove cutoff
plate from housing.

The inducer and blower motors are pre-lubricated and require no
additional lubrication. These motors can be identified by the
absence of oil ports on each end of the motor.

e. Remove bolts holding motor mounts to blower housing and
slide motor and mounts out of housing. Disconnect capacitor and ground wire attached to blower housing before
removing motor.

The following items should be performed by a qualified service
technician.

f. Remove blower wheel from housing.
g. Clean wheel per instructions on degreaser cleaner.

Clean blower motor and wheel as follows:

9. Reassemble motor and blower wheel by reversing items 8b
through 8f. Ensure wheel is positioned for proper rotation. Be
sure to reattach ground wire.

1. Turn off electrical supply to furnace.
2. Remove main furnace door and blower access panel.
3. Disconnect wires.

10. Reinstall blower assembly in furnace.

11. Reinstall condensate trap and tubing if previously removed.

5. Remove wires from gas valve. Note location for reassembly.

a. Reinstall condensate trap in hole in blower shelf.
b. Connect condensate trap drain tubes. See Fig. 8 or tubing
diagram on main furnace door for proper tube location.

Label all wires prior to disconnection when servicing controls. Wiring errors can cause improper and dangerous
operation.

(1.) Connect 1 tube (blue or blue and white striped) from
collector box.
(2.) Connect 1 tube (violet or unmarked) from inducer
housing.

6. Remove burner box pressure tube from gas valve regulator
fitting.

(3.) Connect 1 tube (relief port, green or pink) from
collector box.

7. Remove screws that secure manifold to burner box. (See Fig.
5.)

c. Connect field drain to condensate trap.
NOTE: Ensure tubes are not kinked or pinched, as this will affect
operation.

MANIFOLD
MOUNTING
SCREW

12. Reinstall control box, transformer, and door switch assembly
on blower shelf.
13. Reconnect wires.
Refer to furnace wiring diagram, and connect thermostat leads
if previously disconnected. (See Fig. 15.)
NOTE: Refer to Table 1 for motor speed lead relocation if leads
were not identified before disconnection.

Table 1—Speed Selector
COLOR

SPEED

Black
Yellow (When Present)
Blue
Red
White

High
Medium High
Medium Low
Low
Common

FACTORY
ATTACHED TO
Cool
Spare
Heat
Spare
Com

MANIFOLD
GAS VALVE
REGULATOR
FITTING
GAS VALVE
A93295

Fig. 5—Burner Box Assembly
Heating speed selection MUST be adjusted to provide proper
temperature rise as specified on the rating plate. Failure to
adjust the heating speed may shorten heat exchanger life.

8. Remove manifold, orifices, and gas valve as 1 assembly.
9. Remove screws attaching burner assembly in burner box.
10. Remove burner assembly from burner box.

14. Turn on electrical supply. Manually close blower access panel
door switch. Use a piece of tape to hold switch closed. Check
for proper rotation and speed changes between heating and
cooling by jumpering R to G and R to Y on control center
thermostat terminals. (See Fig. 12.)

NOTE: All burners are attached to burner bracket and can be
removed as 1 assembly.
11. Clean burners with soft brush and vacuum.
12. Reinstall manifold, orifice, and gas valve assembly in burner
box. Ensure manifold seal grommet is installed properly and
burners fit over orifices.

Blower access panel door switch opens 115-v power to
control center. No component operation can occur. Caution
must be taken when manually closing this switch for service
purposes. Failure to follow this warning could result in
personal injury or death.

13. Reconnect wires to gas valve. Refer to furnace wiring diagram
for proper wire location.
14. Reinstall burner box pressure tube to gas valve regulator
fitting.
15. Reinstall gas supply pipe to gas valve using backup wrench on
gas valve to prevent rotation and improper orientation.

15. If furnace is operating properly, release blower access panel
door switch, replace blower access panel, and replace main
furnace door.

NOTE: Use propane gas resistant pipe dope to prevent gas leaks.
DO NOT use Teflon tape.

Step 3—Cleaning Burners
The following items should be performed by a qualified service
technician. If the burners develop an accumulation of light dirt or
dust, they may be cleaned by using the following procedure:

Gas valve switch or knob MUST be facing forward or tilted
upward. Failure to follow this warning could result in
property damage, personal injury, or death.

1. Turn off gas and electrical supplies to furnace.
2. Remove main furnace door.
3. Remove burner box cover.

16. Replace burner box cover.

4. Using backup wrench, disconnect gas supply pipe from gas
valve.

17. Turn on gas and electrical supplies to furnace.
18. Check for gas leaks.

PRIMARY HX
INLET OPENINGS

Never use matches, candles, flame, or other sources of
ignition to check for gas leakage. Use a soap-and-water
solution. Failure to follow this warning could result in a fire,
personal injury, or death.
19. Replace main furnace door.
Step 4—Cleaning Heat Exchangers
The following items should be performed by a qualified service
technician.
PRIMARY HEAT EXCHANGERS
If the heat exchangers get an accumulation of light dirt or dust on
the inside, they may be cleaned by the following procedure:
NOTE: If the heat exchangers get a heavy accumulation of soot
and carbon, both the primary and secondary heat exchangers
should be replaced rather than trying to clean them thoroughly due
to their intricate design. A build-up of soot and carbon indicates
that a problem exists which needs to be corrected, such as
improper adjustment of manifold pressure, insufficient or poor
quality combustion air, improper vent termination, incorrect size
or damaged manifold orifice(s), improper gas, or a restricted heat
exchanger (primary or secondary). Action must be taken to correct
the problem.

A93080

Fig. 6—Cleaning Inlet Openings of Primary Heat
Exchangers
NOTE: Inspect combustion-air intake housing. If foamed gasket
was removed, check for any damage. If gasket is damaged in any
way, it must be repaired. To repair, remove damaged gasket
section, apply sealant releasing agent such as PAM cooking spray
or equivalent (must not contain corn or canola oil, aromatic or
halogenated hydrocarbons or inadequate seal may occur) to burner
box and apply a small bead of G.E. RTV 162. G.E. RTV 6702, or
Dow-Corning RTV 738 sealant to edge of combustion-air intake
housing. (See Fig. 7.)

1. Turn off gas and electrical supplies to furnace.
2. Remove main furnace door.
3. Disconnect wires or connectors to rollout switch, gas valve,
ignitor, and flame sensor.

Label all wires prior to disconnection when servicing controls. Wiring errors can cause improper and dangerous
operation.
4. Disconnect combustion-air intake pipe from intake housing.
5. Remove the pressure switch tube from intake housing.

RTV

6. Remove screws attaching intake housing to burner box, and
rotate intake housing away from burner box for removal.
7. Using backup wrench, disconnect gas supply pipe from gas
valve.

PAM

8. Disconnect pressure tubing from gas valve.
9. Remove 2 screws attaching top filler panel and rotate upwards
to gain access to screws attaching burner box to cell panel.

A93087

Fig. 7—Combustion-Air Intake Housing Gasket
Repair

10. Remove screws attaching burner box to cell panel. (See Fig.
5.)
NOTE: Burner box cover, manifold, gas valve, and burner
assembly should be removed as 1 assembly.

13. Refer to furnace wiring diagram and reconnect wires to rollout
switch, gas valve, ignitor, and flame sensor.
14. Reconnect pressure switch tubes to gas valve and intake
housing. Refer to tube routing label on main furnace door for
proper tube location. Be sure tubes are not kinked. (See Fig.
8.)
15. Turn on gas and electrical supplies to furnace.
16. Check furnace operation through 2 complete heat operating
cycles. Look through sight glass in burner enclosure to check
burners. Burner flames should be clear blue, almost transparent. (See Fig. 9.)
17. Check for gas leaks.

11. Clean heat exchanger openings with a vacuum and a soft
brush. (See Fig. 6.)
NOTE: After cleaning, inspect the heat exchangers to ensure they
are free of all foreign objects that may restrict flow of combustion
products.
12. Reverse items 4 through 10 for reassembly.

The ground wire from the gas valve MUST be attached to the
burner box attachment screw. Failure to attach this ground
wire to an adequate casing ground will cause the furnace
control to lock out.
NOTE: Be sure burner box gasket is installed between burner box
and cell panel. If gasket is damaged, replace it.

TUBE ROUTING
Furnace is shipped from factory in upflow configuration. Pressure tube and drain tube routing MUST match the diagrams below.

BURNER ENCLOSURE
PRESSURE REFERENCE
TUBE ASSEMBLY

(Blower access panel removed)

CAP

COLLECTOR BOX TUBE
(PINK)

PLUG

COLLECTOR BOX TUBE
(GREEN)

COLLECTOR BOX TUBE (GREEN)

CONDENSATE TRAP

COLLECTOR BOX DRAIN TUBE
(BLUE & WHITE STRIPED)

COLLECTOR BOX DRAIN TUBE
(BLUE)

COLLECTOR BOX DRAIN TUBE
(BLUE)
FIELD-INSTALLED
FACTORY-SUPPLIED
DRAIN TUBE COUPLING
(RIGHT DRAIN OPTION)

FIELD-INSTALLED
FACTORY-SUPPLIED DRAIN TUBE
COUPLING (LEFT DRAIN OPTION)

CONDENSATE TRAP
INDUCER HOUSING DRAIN TUBE
(VIOLET)

FIELD-INSTALLED
FACTORY-SUPPLIED 1/2-IN.
CPVC STREET ELBOWS (2)
FOR LEFT DRAIN OPTION

FIELD-INSTALLED FACTORY-SUPPLIED
DRAIN TUBE

Condensate Trap on
RIGHT Side

Tube location when used in DOWNFLOW application
PLUG

COLLECTOR BOX
DRAIN TUBE (BLUE)
PLUGGED END

CAP

CAP
COLLECTOR BOX DRAIN TUBE
(BLUE)

COLLECTOR BOX DRAIN
TUBE
(BLUE & WHITE STRIPED)

COLLECTOR BOX
TUBE (GREEN)

COLLECTOR BOX TUBE
(PINK)

PLUG

COLLECTOR BOX DRAIN TUBE
(BLUE & WHITE STRIPED)

COLLECTOR BOX TUBE
(GREEN)

INDUCER HOUSING DRAIN
TUBE (VIOLET)

COLLECTOR BOX
EXTENSION TUBE

COLLECTOR BOX EXTENSION TUBE
BURNER ENCLOSURE PRESSURE
REFERENCE TUBE ASSEMBLY

COLLECTOR BOX
EXTENSION TUBE

CONDENSATE TRAP

DRAIN TUBE COUPLING

COLLECTOR BOX
TUBE (PINK)

BURNER ENCLOSURE PRESSURE
REFERENCE TUBE ASSEMBLY

DRAIN TUBES ROUTED IN
FRONT OF GAS VALVE

INDUCER HOUSING DRAIN TUBE (VIOLET)

Tube location when used on
HORIZONTAL - LEFT application
AUXILIARY "J" BOX RELOCATED HERE

CONDENSATE TRAP

GAS VALVE

COLLECTOR BOX DRAIN TUBE
(BLUE)

COLLECTOR BOX DRAIN TUBE
(BLUE & WHITE STRIPED)

CAP

COLLECTOR BOX EXTENSION TUBE
COLLECTOR BOX TUBE (PINK)

PLUG

COLLECTOR BOX
TUBE (GREEN)

BURNER ENCLOSURE
PRESSURE REFERENCE
TUBE ASSEMBLY

INDUCER HOUSING
DRAIN TUBE
(VIOLET)

COLLECTOR BOX
EXTENSION TUBE

CAP

COLLECTOR BOX
DRAIN TUBE (BLUE)

CONDENSATE TRAP
DRAIN TUBE
COUPLING

NOTE:

COLLECTOR BOX
EXTENSION DRAIN TUBE

Tube location when used on
HORIZONTAL - RIGHT application

PLUG

COLLECTOR BOX EXTENSION DRAIN TUBE

BURNER ENCLOSURE
PRESSURE REFERENCE
TUBE ASSEMBLY

PLUG

COLLECTOR BOX TUBE
(PINK)

COLLECTOR BOX DRAIN
TUBE
(BLUE & WHITE STRIPED)

INDUCER HOUSING (MOLDED) DRAIN TUBE
(BEHIND COLLECTOR BOX DRAIN TUBE)

Condensate Trap on
LEFT Side

Condensate Trap on LEFT
Side Optional

Tube location when used in UPFLOW application

Condensate Trap; Factory Installed
in Blower Shelf

BURNER ENCLOSURE
PRESSURE REFERENCE
TUBE ASSEMBLY
COLLECTOR BOX
EXTENSION TUBE

COLLECTOR BOX
TUBE (GREEN)

COLLECTOR BOX TUBE (PINK)
RELOCATE TUBE BETWEEN BLOWER
SHELF AND INDUCER HOUSING FOR
040,060, AND 080 HEATING INPUT
FURNACES

COLLECTOR BOX DRAIN TUBE
(BLUE AND WHITE STRIPED)

CONDENSATE TRAP
INDUCER HOUSING DRAIN TUBE (VIOLET)

1. All tubing must be connected securely and routed to avoid kinks and traps.
2. Pressure tubing must always slope away from pressure switch to collector box connection as shown.
3. HORIZONTAL-LEFT installations require the collector box pressure tube to be relocated between the inducer housing and the blower shelf to
prevent a trap.Refer to the Installation Instructions for further details.

324999-201 REV. A
(LIT. BOTTOM)

→ Fig. 8—Furnace Pressure and Drain Tubing Diagram

A99102

BURNER FLAME
BURNER

Never use matches, candles, flame, or other sources of
ignition to check for gas leakage. Use a soap-and-water
solution. Failure to follow this warning could result in a fire,
personal injury, or death.
18. Replace main furnace door.
SECONDARY HEAT EXCHANGERS
NOTE: The condensing side (inside) of the secondary heat
exchangers CANNOT be serviced or inspected. A small number of
bottom outlet openings can be inspected by removing the inducer
assembly. See Flushing Collector Box and Drainage System
section for details on removing inducer assembly.
Step 5—Flushing Collector Box and Drainage
System

MANIFOLD
A89020

1. Turn off gas and electrical supplies to furnace.

Fig. 9—Burner Flame

2. Remove main furnace door.
3. Disconnect inducer motor and pressure switch wires or
connectors.

→

14. Check furnace operation through 2 complete heat operating
cycles. Check area below inducer housing, vent pipe, and
condensate trap to ensure no condensate leaks occur. If leaks
are found, correct the problem.

4. Disconnect pressure switch tubes.
5. Disconnect vent pipe from inducer housing outlet by loosening coupling clamp on inducer outlet.
6. Disconnect drain tube from inducer housing. (See Fig. 8.)

15. Check for gas leaks.

7. Remove inducer housing assembly by removing 4 bolts
attaching assembly to cell panel.
8. Flush inside of collector box with water until discharge from
condensate trap is clean and runs freely.

NOTE: Ensure the drain tube disconnected from the inducer
housing is higher than the collector box opening or water will flow
out tube.

16. Replace main furnace door.

9. Inspect inside area of collector box for any pieces of foreign
materials and remove if present.

Step 6—Servicing Hot Surface Ignitor
The ignitor does NOT require annual inspection. Check ignitor
resistance before removal.

DO NOT use wire brush or other sharp object to inspect or
dislodge materials in secondary heat exchangers as failure of
the secondary heat exchanger will occur. Flush with water
only.

→ 10.

1. Turn off gas and electrical supplies to furnace.
2. Remove main furnace door.
3. Disconnect ignitor wire connection.
4. Check ignitor resistance.

Reassemble inducer assembly by reversing items 5 through 7.
Tighten the vent coupling clamp screw(s) to 15 in.-lb. of
torque.

a. Using an ohm meter, check resistance across both ignitor
leads in connector.
b. Cold reading should be between 45 ohms and 90 ohms.

NOTE: If seal between the inducer housing and the collector box
is damaged in any way, it must be repaired. To repair, apply
sealant releasing agent such as PAM cooking spray or equivalent
(must not contain corn or canola oil, aromatic or halogenated
hydrocarbons or inadequate seal may occur) to inducer housing.
(See Fig. 10.) Apply a small bead of G.E. RTV 162, G.E. RTV
6702, or Dow-Corning RTV 738 sealant to groove in collector
box.

c. If ohm reading is higher than 110 ohms, ignitor is cracked
and must be replaced.
5. Remove ignitor assembly.

Allow ignitor to cool before removal. Normal operation
temperatures exceed 2000°F.
a. Do not remove ignitor from bracket while assembly is in
furnace. Using a 1/4 in. nutdriver, remove screw securing
bracket and ignitor assembly to bottom of burner box. The
screw in the bracket is always located toward outside of
burner box. The screw may be hidden by inlet box or inlet
pipe, but can be removed without removing either. After
removing screw, slide ignitor and bracket toward outside of
burner box and pull straight out.

PAM
RTV

The ignitor is fragile. DO NOT allow it to hit the side of the
burner box opening while removing or replacing it.
b. Inspect ignitor for a white area indicating a crack may be
present. If found, replace ignitor.
NOTE: A small crack cannot be seen on a new ignitor. After a
period of operation, a white area will be visible around the crack.
c. If replacement is required, replace ignitor on ignitor bracket
external to furnace to avoid damage as the silicon portion is
very brittle and will easily crack or shatter.
A93081

d. To remove ignitor from ignitor bracket, remove screw
holding ignitor ceramic block to bracket and pull ceramic
block out of bracket.

11. Refer to furnace wiring diagram and reconnect wires to
inducer motor and pressure switch or connectors.

6. To replace ignitor/ignitor assembly, reverse items 5a through
5d.

12. Reconnect pressure tubes to pressure switch. See diagram on
main furnace door for proper location of tubes. Be sure tubes
are not kinked. (See Fig. 8.)

7. Reconnect ignitor wire connection.

Fig. 10—Gasket on Collector Box

8. Turn on gas and electrical supplies to furnace.
9. Verify ignitor operation by initiating control board self-test
feature or by cycling thermostat.

13. Turn on gas and electrical supplies to furnace.

The control center stores 1 status code (representing the last fault
to occur) for a period of 48 hr or until the 115- or 24-v power is
interrupted.

10. Replace main furnace door.
Step 7—Electrical Controls and Wiring

NOTE: Removing blower access panel will open blower access
panel door switch and terminate 115-v power to control center.
The status code will be erased. Look into blower access panel sight
glass for current LED status BEFORE removing blower access
panel.

There may be more than 1 electrical supply to the unit. Check
accessories and cooling unit for additional electrical supplies.
The electrical ground and polarity for 115-v wiring must be
maintained properly. Refer to Fig. 11 for field wiring information
and to Fig. 15 for unit wiring information.

The unit’s component test is a useful troubleshooting tool since it
displays the current status code of the furnace and functionally
operates all furnace components except the gas valve. The component test and methods to initiate it are described below.

NOTE: If the polarity is not correct, the STATUS LED on the
control center will flash rapidly and prevent the furnace from
operating. The control system also requires an earth ground for
proper operation of the control center and flame sensing.

COMPONENT TEST SEQUENCE
NOTE: All components are functionally operated except the gas
valve.

The 24-v circuit contains an automotive-type, 3-amp fuse located
on the control center. (See Fig. 12.) Any direct shorts of the 24-v
wiring during installation, service, or maintenance will cause this
fuse to blow. If fuse replacement is required, use ONLY a fuse of
identical size.

When component test is initiated, the following sequence of events
occurs:
1. LED flashes a status code 4 times.
2. Inducer motor starts and continues to run for remainder of
component test.

With power to the unit disconnected, check all electrical connections for tightness. Tighten all screws on electrical connections. If
any smoky or burned connections are found, disassemble the
connection, clean all parts, strip wire, and reassemble properly and
securely.

3. Hot surface ignitor is energized for 15 sec, then de-energized.
4. Main blower operates at cooling speed for 10 sec, then turns
off.
5. Main blower operates at heating speed for 10 sec, then turns
off.

Reconnect electrical supply to unit and observe unit through 1
complete operating cycle. Electrical controls are difficult to check
without proper instrumentation; if there are any discrepancies in
the operating cycle, contact your dealer and request service.

6. Inducer motor stops.
Component test can be initiated by one of the following procedures.
INITIATING COMPONENT TEST AND RETRIEVING STATUS CODE BY REMOVING MAIN LIMIT SWITCH WIRE

Step 8—Troubleshooting
For an explanation of status codes, refer to service label located on
back of main furnace door or Fig. 16, and the Troubleshooting
Guide.

NOTE: NO thermostat signal may be present at control center
and all blower time delay off periods must be completed.
FIELD 24-V WIRING
FIELD 115-, 208/230-, 460-V WIRING
FACTORY 24-V WIRING
FACTORY 115-, 208/230-, 460-V WIRING

NOTE 5
W

FIVE
WIRE

THERMOSTAT
TERMINALS

FIELD-SUPPLIED
DISCONNECT

THREE-WIRE
HEATING
ONLY

208/230- OR
460-V
THREE PHASE
W/W1

GND

115-V
SINGLE
PHASE

NOTE
3

GND

AUXILIARY
115-V
FIELD-SUPPLIED J-BOX
DISCONNECT
SWITCH
FURNACE
CONTROL
CENTER

208/230-V
SINGLE
PHASE

G
C

GND

NOTE 1

24-V
TERMINAL
BLOCK

GND

CONDENSING
UNIT

Y/Y2

TWO WIRE
NOTES:
1. Connect Y or Y/Y2 terminal as shown for proper cooling operation.
2. Proper polarity must be maintained for 115-v wiring.
3. Use W2 with 2-stage thermostat when zoning.
4. If any of the original wire, as supplied, must be replaced, use
same type or equivalent wire.
5. Some thermostats require a "C" terminal connection as shown.
A98325

Fig. 11—Field Wiring
8

BLOWER OFF DELAY
ADJUSTMENT SWITCH
24V THERMOSTAT
TERMINALS

G
R
Y
W
Com

TEST/TWIN

24V
HUM

HUMIDIFIER TERMINAL
(24-VAC 0.5 AMP MAX)
LED OPERATION &
STATUS LIGHT

HARNESS CONNECTOR
SEC-1

24V TRANSFORMER SEC-2

3-AMP FUSE

SPARE 1

COOL
HEAT

BLOWER SPEED
SELECTION TERMINALS
SPARE 2
EAC 1 (BLACK)
EAC-ELECTRONIC AIR CLEANER
TERMINALS (115-VAC 1.5 AMP MAX)

115-VAC (L1)
POWER
SUPPLY
HOT SURFACE
IGNITOR
CONNECTOR

EAC 2 (WHITE)
115-VAC (L2) NEUTRAL
CONNECTION
INDUCER MOTOR
CONNECTOR
A93052

Fig. 12—Control Center
1. Leave 115-v power to furnace turned on.

3. Manually close blower access panel door switch. Use a piece
of tape to hold switch closed.

2. Remove main furnace door.
3. Look into blower access panel sight glass for current LED
status.
NOTE: Leave blower access panel installed to maintain power to
control center to view current LED status.

4. BRIEFLY remove either wire from the main limit switch until
the LED goes out, then reconnect it.

4. BRIEFLY short (jumper) TEST, 1/4-in. quick-connect terminal on control center (adjacent to the LED diagnostic light)
and the COM terminal on thermostat connection block. (See
Fig. 12.)

Make sure limit switch wire does not contact any metallic
component such as the gas valve. If wire is shorted, 3-amp
fuse on control center will blow.

NOTE: If TEST to COM terminals are jumpered longer than 2 sec,
LED will flash rapidly, and retrieval request will be ignored.

NOTE: If wire to main limit is disconnected longer than 4 sec, the
control senses limit circuit is open. Main blower will start and
retrieval request will be ignored.

5. When above items have been completed, the component test
sequence will occur as described in the Component Test
Sequence section above.

NOTE: Be sure to record the status code which is flashed 4 times
at start of component test for further troubleshooting.

6. After component test is completed and furnace is operating
properly, release blower access panel door switch, replace
blower access panel, and replace main furnace door.

6. After component test is completed and LED is ON continuously indicating the furnace is ready to operate when a signal
from the thermostat is received, replace main furnace door.

Step 9—Checking Heat Tape Operation (If Applicable)

INITIATING COMPONENT TEST AND RETRIEVING STATUS CODE BY JUMPERING CONTROL TEST TERMINAL

In applications where the ambient temperature around the furnace
is 32°F or lower, freeze protection measures are required. If this
application is where heat tape has been applied, check to ensure it
will operate when low temperatures are present.

1. Remove main furnace door.
2. Remove blower access panel.

1. Check for signs of physical damage to heat tape such as nicks,
cuts, abrasions, gnawing by animals, etc.
2. Check for discolored heat tape insulation. If any damage or
discolored insulation is evident, replace heat tape.
3. Check that heat tape power supply circuit is on.
Step 10—Winterizing

32°F MINIMUM INSTALLED
AMBIENT OR FREEZE
PROTECTION REQUIRED

Freezing condensate left in the furnace will damage the
equipment.
If the furnace will be off for an extended period of time in a
structure where the temperature will drop to 32°F or below,
winterize as follows:
1. Turn off electrical supply to furnace.
2. Remove main furnace door.
3. Disconnect drain tube from inducer housing. (See Fig. 13.)
4. Insert funnel in drain tube and pour antifreeze, propylene
glycol (RV, swimming pool antifreeze, or equivalent) into
furnace until it is visible at point where condensate enters open
drain. (See Fig. 14.)
5. Reconnect drain tube to inducer housing.
6. Replace main furnace door.

A93058

If this furnace is installed in an unconditioned space where
the ambient temperatures may be 32°F or lower, freeze
protection measures must be taken.

Do not use ethylene glycol (Prestone II antifreeze/coolant or
equivalent automotive type). Failure of plastic components
will occur.

NOTE: Heat tape, when used, should be wrapped around the
condensate drain trap and drain line. There is no need to use heat
tape within the furnace casing. Most heat tapes are temperature
activated, and it is not practical to verify the actual heating of the
tape. Check the following:

A99118

A99119

→ Fig. 13—Inducer Housing Drain Tube

→ Fig. 14—Funnel in Drain and Antifreeze Running
Through Trap
10

SEE NOTE #10

(NOT ON ALL MODELS)

SW2
BLOWER
OFF
DELAY SW1

BLOWER OFF DELAY
SELECTION CHART

G
R
Y
W
COM
HUM
LED

135 SEC
225 SEC

WHT

FSE
RED

SEC-1

SEC-2

BLU

HI/LO
RELAY

1
2
3

WHT
GRN

HSI

EAC-2

BLK

1
2

PL2

PL5

HSI

WHT

PR1

PR2

115VAC

TRAN

BRN
OL

24VAC
START

CAP -1
TEST/TWIN FU1

BLU (MED LO)

BRN

SEC-1

CAP -2

FRS

SEC-2

GVR-2

7
1

IDM

WHT

ILK

HSIR

FUSED DISCONNECT
SWITCH (WHEN REQ'D)
NOTE #4

BRN

AUX

LEGEND
BLOWER MOTOR RELAY, SPST-(N.O.)
BLOWER MOTOR
CAPACITOR
MICROPROCESSOR AND CIRCUITRY
ELECTRONIC AIR CLEANER CONNECTION (115 VAC 1.5 AMP MAX.)
ELECTRONIC AIR CLEANER CONNECTION (COMMON)
FLAME ROLLOUT SW. -MANUAL RESET, SPST-(N.C.)
FLAME PROVING ELECTRODE
FUSE, 3 AMP, AUTOMOTIVE BLADE TYPE, FACTORY INSTALLED
FUSE OR CIRCUIT BREAKER CURRENT INTERRUPT DEVICE
(FIELD INSTALLED & SUPPLIED)
EQUIPMENT GROUND
GAS VALVE-REDUNDANT OPERATORS
GAS VALVE RELAY, DPST-(N.O.)
BLOWER MOTOR SPEED CHANGE RELAY, SPDT
HOT SURFACE IGNITOR (115 VAC)
HOT SURFACE IGNITOR RELAY, SPST-(N.O.)
24VAC HUMIDIFIER CONNECTION (.5 AMP. MAX.)
INDUCED DRAFT MOTOR
INDUCED DRAFT RELAY, SPST-(N.O.)
BLOWER ACCESS PANEL INTERLOCK SWITCH, SPST-(N.O.)
JUNCTION BOX
LIGHT-EMITTING DIODE FOR STATUS CODES
LOW GAS PRESSURE SWITCH, SPST-(N.O.)
LIMIT SWITCH, AUTO RESET, SPST(N.C.)
AUTO-RESET INTERNAL MOTOR OVERLOAD TEMP. SW.
PRINTED CIRCUIT BOARD

(WHEN USED)

CAP -2

LGPS

BLK
GRN

BLWR
IDR

HI/LO
PL1

GVR

NEUTRAL
FU2

PL1
PL2
PL3
PL4
PL5
PRS
SW1 & 2
TEST/TWIN
TRAN

NOTE #6
PRS

GVR-1
CPU

3-P

9-CIRCUIT CONNECTOR
2-CIRCUIT PCB CONNECTOR
3-CIRCUIT IDM CONNECTOR
3-CIRCUIT IDM EXTENSION CONNECTOR
2-CIRCUIT HSI/PCB CONNECTOR
PRESSURE SWITCH, SPST-(N.O.)
BLOWER OFF DELAY
COMPONENT TEST & TWIN TERMINAL
TRANSFORMER-115VAC/24VAC
JUNCTION
UNMARKED TERMINAL
PCB TERMINAL
FACTORY WIRING (115VAC)
FACTORY WIRING (24VAC)
FIELD WIRING (115VAC)
FIELD WIRING (24VAC)
CONDUCTOR ON PCB
FIELD WIRING TERMINAL
FIELD EARTH GROUND
EQUIPMENT GROUND
FIELD SPLICE
PLUG RECEPTACLE

2
1-M

GND

GND
GV
GVR
HI/LO
HSI
HSIR
HUM
IDM
IDR
ILK
JB
LED
LGPS
LS
OL
PCB

BRN

GRN

BLWR
BLWM
CAP
CPU
EAC-1
EAC-2
FRS
FSE
FU1
FU2

AUX

NOTE #7

NOTE #12
HUM

BLWM

RED (LO)

BRN
PL4

PL3

YEL (MED HI)
NOTE #8

IDM
OL

IDR

WHT
BLK

BRN

CAP-1
BLWM

NOTE #5

WHT (COM)

1 2 3 PL4
PL5

EAC-2
COM

GRN
WHT
WHT

BLK
BLK

PR2

1.5 AMP

PL3
1
2

WHT

BLK

COOL SPARE-1
BLOWER
SPEED
SELECT
HEAT SPARE-2
EAC-1
L2

BLWR

PL2

HSIR

WHT (COM)
GRN

BLK (HI)

START
OL

EAC-1

2-C

BLK

RED
24 VAC-3A
FU1 FUSE

120 VAC
L1 PR1

SPARE-1
NOTE #8
COOL
COM
COM

GRN

GVR

IDR

FRS

WHT

HI/LO

BLWR

3-P

1-M

LO
MED LO
MED HI
HI

SPARE-2
HEAT
L1

BLU

3 2 1
6 5 4
9 8 7

EQUIPMENT GROUND

YEL

RED

RED
PL1

SCHEMATIC DIAGRAM
(NATURAL GAS & PROPANE)

GND

ILK
NOTE #6

90 SEC

HSIR

ORN

TEST/TWIN

180 SEC

TO 115VAC FIELD DISCONNECT
NOTE #4
NEUTRAL

(WHEN USED)
LGPS

PRS

TRAN

PCB

2-C
NOTE #5

FSE

COM

NOTES:

1. IF ANY OF THE ORIGINAL EQUIPMENT WIRE IS REPLACED USE WIRE RATED FOR 105˚C.
2. INDUCER (IDM) AND BLOWER (BLWM) MOTORS CONTAIN INTERNAL
AUTO-RESET THERMAL OVERLOAD SWITCHES (OL).
3. BLOWER MOTOR SPEED SELECTIONS ARE FOR AVERAGE CONDITIONS, SEE INSTALLATION
INSTRUCTIONS FOR DETAILS ON OPTIMUM SPEED SELECTION.
4. USE ONLY COPPER WIRE BETWEEN THE DISCONNECT SWITCH AND THE
FURNACE JUNCTION BOX (JB).
5. THIS WIRE MUST BE CONNECTED TO FURNACE SHEETMETAL FOR CONTROL TO PROVE
FLAME.
6. FACTORY CONNECTED WHEN LGPS NOT USED.
7. REPLACE ONLY WITH A 3 AMP FUSE.
8. YELLOW LEAD NOT ON ALL MOTORS.
9. BLOWER-ON DELAY, GAS HEATING 60 SECONDS, COOLING OR HEAT PUMP 2 SECONDS.
10. BLOWER-OFF DELAY, GAS HEATING 90, 135, 180 OR 225 SECONDS, COOLING OR
HEAT PUMP 90 SECONDS. (135 SECONDS ONLY ON SOME MODELS)
11. IGNITION-LOCKOUT WILL OCCUR AFTER FOUR CONSECUTIVE UNSUCCESSFUL
TRIALS-FOR-IGNITION. CONTROL WILL AUTO-RESET AFTER THREE HOURS.
12. SOME MODELS MAY HAVE SPADE QUICK CONNECT TERMINALS.

322854-101 REV. D (LIT)

→ Fig. 15—Wiring Diagram

A99106

SERVICE
If status code recall is needed, do not remove power or blower door. Briefly remove and then
reconnect one main limit wire to display stored status code.

LED CODE

STATUS

CONTINUOUS OFF -

Check for 115VAC at L1 and L2, and 24VAC at SEC-1 and
SEC-2.
CONTINUOUS ON - Control has 24V power.
RAPID FLASHING Line voltage (115V) polarity reversed. If twinned, refer to
twinning kit instructions.
EACH OF THE FOLLOWING STATUS CODES IS A TWO DIGIT NUMBER WITH THE FIRST
DIGIT DETERMINED BY THE NUMBER OF SHORT FLASHES AND THE SECOND DIGIT BY
THE NUMBER OF LONG FLASHES.
11 NO PREVIOUS CODE - Stored status codes are erased when power
(115V or 24V) to control is interrupted or 48 hours after each fault is cleared.
12 BLOWER ON AFTER POWER UP (115V or 24V) - Blower runs for 90 seconds,
if unit is powered up during a call for heat (R-W closed).
13 LIMIT OR FLAME ROLL-OUT SWITCH LOCKOUT - Control will auto reset after
three hours unless flame roll-out switch or fuse link is opened, refer to #33.
14 IGNITION LOCKOUT - Control will auto-reset after three hours. Refer to #34.
21 GAS HEATING LOCKOUT - Control will NOT auto reset.
Check for: - Mis-wired gas valve
-Defective control (valve relay)
22 ABNORMAL FLAME-PROVING SIGNAL - Flame is proved while gas valve is
de-energized. Inducer will run until fault is cleared.
Check for:
- Leaky gas valve
-Stuck-open gas valve
23 PRESSURE SWITCH (ES) DID NOT OPEN Check for:
- Obstructed pressure tubing.
- Defective pressure switch (stuck closed).
24 SECONDARY VOLTAGE FUSE IS OPEN
Check for: - Short circuit in secondary voltage (24V) wiring.
31 PRESSURE, DRAFT SAFEGUARD, AUXILIARY-LIMIT (when used) , OR BLOCKED
VENT SHUTOFF (when used) SWITCH DID NOT CLOSE OR REOPENED - If open
longer than five minutes, inducer shuts off for 15 minutes before retry.
Check for:
- Inadequate Combustion air supply.
- Proper vent sizing and condensate pitch or sag
- Low inducer voltage.
- Vent restriction or high winds.
- Disconnected or obstructed pressure tubing
- Defective inducer motor or start capacitor.
- Defective pressure switch or connections. If it opens after trial for ignition
period, blower will come on for 90 second recycle delay.
33 LIMIT OR FLAME ROLL-OUT SWITCH IS OPEN - If open longer than three
minutes, code changes to #13. Flame roll-out switch requires manual reset.
Check for: - Defective blower motor or capacitor.
- Dirty filter or restricted duct system.
- Loose blower wheel.
- Defective switch or connections.
- Inadequate Combustion air supply (Flame Roll-out Switch or fuse link).
- Open Flame Roll-out switch,or fuse link. Manual reset or replace.
34 IGNITION PROVING FAILURE - Control will try three more times before a
lockout #14 occurs. If flame signal lost after trial for ignition period, blower
will come on for 90 second recycle delay. Check for:
- Oxide buildup on flame sensor (clean with fine steel wool).
- Proper flame sense microamps (.5 microamps D.C. min., 4.0 - 6.0 nominal).
- Gas valve defective or gas valve turned off.
- Defective Hot Surface Ignitor
- Manual valve shut-off.
- Low inlet gas pressure.
- Green wire MUST be connected to furnace sheet metal.
- Inadequate flame carryover or rough ignition.

COMPONENT TEST
To initiate the component test sequence,shut OFF the room thermostat or
disconnect the "R" thermostat lead. Briefly short the TEST terminal to the "Com
24V" terminal. Status LED will flash code and then turn ON the inducer motor. The
inducer motor will run for the entire component test. The hot surface ignitor,
blower motor-heat speed, and blower motor-cool speed will be turned ON for
10-15 seconds each. Gas Valve and Humidifier will not be turned on.

TEST

STATUS

HUM

Com
24V

320615-102 REV. J
A99107

→ Fig. 16—Service Label

START

Go to section with status code
determined.

Determine status code. The
status code is a 2 digit number
with the first digit determined by
the number of short flashes and
the second digit by the number of
long flashes.

YES

Is red LED status light blinking
ON/OFF slowly with a
combination of short and long
flashes?

Is red LED status light blinking
rapidly without a pause?

YES

Is red LED status light on?

YES

Was there a previous fault code
other than No. 11?

Check for previous fault by
momentarily shorting the TEST
terminal and the C terminal until
the LED goes out. LED will flash
the status code of any previous
fault or the code No. 11 (1 short
and 1 long flash) if no previous
fault. After the control repeats the
code 3 times, the control will go
through a brief component test
sequence. The inducer will start
and run for the entire component
test. The HSI, blower motor heat
speed, and blower motor cool
speed will run for 10-15 sec each.

Check for correct line voltage
polarity. If units are twinned,
check for proper low-voltage
(24v) transformer phasing.

Replace control center.

YES

Is there 24v at SEC-1 and SEC-2?

YES

Is there 115v at L1 and L2?

Run system through a heating or
cooling cycle to check operation.
Status codes are erased after 48
hrs or whenever power (115v
or 24v) is interrupted.

YES

Does control respond to W, Y,
or G 24-vac thermostat signals?

Replace transformer.

Replace door switch.

YES

Is there 115v going to switch?

YES

Is door switch closed?

→ Troubleshooting Guide

Replace control if it does not
respond to 24-vac signal at W, Y,
or G screw terminals.

YES

Is 24 vac present at W, Y, or G
terminals on the control?

Check room thermostat or
interconnecting cable.

Close circuit breaker and
go back to start.

Check for continuity in wire from circuit
breaker to furnace.

YES

Is circuit breaker closed?

Close door switch and go to start.

24 LOW-VOLTAGE FUSE IS
OPEN - Check for:
• Short in low-voltage wiring
including thermostat leads
shorting to ductwork or
furnace cabinet. Disconnect
thermostat leads to isolate
short circuit.

23 PRESSURE SWITCH WILL
NOT OPEN - Check for:
• Disconnected or obstructed
pressure tubing.
• Defective pressure switch.

22 ABNORMAL FLAME PROVING
SIGNAL - Flame was sensed
while gas valve was
de-energized. Inducer will run
until fault is cleared.
Check for:
• Stuck open gas valve solenoid
or leak.
• Defective control center.

21 GAS HEATING LOCKOUT Turn off power and wait 5
minutes to retry.
Check for:
• Stuck closed gas valve relay
on control.
• Miswire or short to gas valve
wire.

14 IGNITION LOCKOUT - System
failed to ignite gas and prove
flame in 4 attempts. Control will
auto-reset in 3 hrs.
See No. 34

13 LIMIT OR FLAME ROLLOUT
SWITCH LOCKOUT Limit switch was open longer
than 3 minutes. Auto-reset will
occur after 3 hrs. Flame rollout
switch requires manual reset.
See No. 33

12 BLOWER ON AFTER POWER
UP (115V OR 24V) - Normal
operation. Blower will run for 90
sec when furnace power is
interrupted during a call for heat,
R-W closed.

11 NO PREVIOUS FAULT - Faults
are erased after 48 hrs or
whenever power (115v or 24v) is
interrupted. Run system through
a heating or cooling cycle to
check system.

YES

34 IGNITION PROVING FAILURE If flame is not sensed during the
trial for ignition period, the control
will repeat the ignition sequence
3 more times before going into
lockout, No. 14.
If flame signal is lost after trial for
ignition period, blower will come
on for 90-sec recycle delay.
Check for the following items first
before proceding to the next step.
• Gas valve turned off.
• Manual shut-off valve.
• Green wire must be connected NO
to furnace sheet metal.
To determine whether the
problem is in the gas valve,
ignitor, or flame sensor, the
system can be operated in the
component test mode to check
the ignitor. First, remove the
R thermostat connection from the
control center and initiate the
component test sequence. Does
the ignitor glow orange/white hot
by the end of the 17-sec warm-up
period?

33 LIMIT OR FLAME ROLLOUT
SWITCH IS OPEN - If
limit switch is open longer than 3
minutes, code changes to No. 13.
Check for:
• Blower motor failure.
• Motor start capacitor.
• Open flame rollout switch,
manual reset.
• Inadequate combustion air
supply (flame rollout switch
only).
• Dirty filter.
• Defective limit switch or
connections.
• Loose blower wheel.

31 PRESSURE SWITCH WILL
NOT CLOSE OR REOPEN - If
open longer than 5 minutes,
inducer shuts off for 15 minutes
before retry.
Check for:
• Proper vent sizing or pitch or
sag.
• Vent restrictions or high winds.
• Defective inducer motor.
• Low line voltage (115v).
• Motor start capacitor.
• Low inlet gas pressure.
• Defective pressure switch or
connections. If it opens after
trial for ignition period, blower
will come on for 90 sec
recycle delay.
• Inadequate combustion air.

Allow blower to come on and repeat
test to check for intermittent
operation.

YES

Do main burners stay on?

YES

Do main burners ignite?

YES

Does gas valve open and allow gas
to flow?

YES

Reconnect the R thermostat lead
and set thermostat to call for heat.
Connect voltmeter across gas valve
connections. Does gas valve
receive 24v?

Check for continuity in the harness
and ignitor. Replace defective
component.

YES

Unplug ignitor harness from control
center and inititate another
component test sequence. Check
for 115v between pins 1 and 2 on
the control center. Was 115v present
for the 17-sec period?

Fixed.

YES

Will main burner ignite and stay on?

YES

Is current near typical value?

A99123

Replace control center.

Replace electrode.

Check connections and retry. If
current is near typical value and
control will not stay on, replace
control center.

Clean flame sensor with fine
sandpaper and recheck current.
Current is nominally 4.0 to 6.0 microamps.

YES

Repeat call for heat and check flame
sensor current during trial for ignition
period. Is the DC microamps
below 0.5?

Check for:
• Inadequate flame carryover on
rough ignition.
• Low inlet gas pressure.

Check that all gas valves are turned
on. Replace valve.

Check connections. If OK, replace
control center.

Replace control center.

SERVICE TRAINING
Packaged Service Training programs are an excellent way to increase your
knowledge of the equipment discussed in this manual, including:
• Unit Familiarization
• Maintenance
• Installation Overview
• Operating Sequence
A large selection of product, theory, and skills programs is available, using popular
video-based formats and materials. All include video and/or slides, plus companion
book.
Classroom Service Training plus "hands-on" the products in our labs can mean
increased confidence that really pays dividends in faster troubleshooting, fewer
callbacks. Course descriptions and schedules are in our catalog.
CALL FOR FREE CATALOG 1-800-962-9212
[ ] Packaged Service Training

[ ] Classroom Service Training
A94328

58mxa6sm

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XMP Toolkit                     : 3.1-701
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Metadata Date                   : 2005:11:14 11:01:51-05:00
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Carrier 58Mxa Users Manual

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