Carrier 58MVP User Manual

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58MVP

Variable-Speed 2-Stage

Electronic Condensing Furnace

Troubleshooting Guide

NOTE: Read the entire instruction manual before starting the

installation.

SAFETY CONSIDERATIONS

INDEX

PAGE

Instructions .....................................................................................1

Example..........................................................................................2

Sequence of Operation................................................................1-5

Self-Test Mode..........................................................................2

Heating Mode............................................................................2

Heating Mode-Two Stage.........................................................2

Emergency Heat Mode..........................................................2-3

Cooling Mode ...........................................................................3

Heat Pump Mode...................................................................3-4

Continuous Fan Mode ..............................................................4

Component Test.....................................................................4-5

Bypass Humidifier Mode..........................................................5

Dehumidification Mode............................................................5

Zone Mode................................................................................5

Start Here........................................................................................6

Service Label/Fault Code Instructions.......................................7-8

Improper Operation With No Flashing Fault Code......................9

Not Enough Cooling Airflow......................................................10

High-Fire Temperature Rise Too Low (Cold Blow)..................11

LEDs 1, 2, 3, or 4 On Solid...................................................11-12

RED LED2 Flashing....................................................................12

Fault Code 11—No Fault in Recent History Display ................13

Fault Code 12—Blower Calibration Lockout........................13-15

Fault Code 13—Limit Switch Lockout..................................15-16

Fault Code 14—Ignition Lockout................................................17

Fault Code 21—Invalid Model Selection....................................17

Fault Code 22—Set Up Error......................................................18

Fault Code 23—Invalid Blower Airflow Selection....................18

Fault Code 24—Secondary Voltage Fuse Is Open................19-20

Fault Code 31—High-Pressure Switch Fault.........................21-22

Fault Code 32—Low-Pressure Switch Fault .........................23-24

Fault Code 33—Limit Switch Fault.......................................24-25

Fault Code 34—Ignition Proving Fault .................................26-27

Fault Code 41—Blower Outside Valid Speed Range...........27-28

Fault Code 42—Inducer Outside Valid Speed Range...........29-30

Fault Code 43—Pressure Switch Calibration Fault...............30-31

Fault Code 44—Blower Calibration Fault..................................32

Cleanup and Start-Up Instructions ..............................................33

APPENDIX A—Board Layout & Wiring Schematic ...........34-35

APPENDIX B—Isolation Circuits ..............................................36

APPENDIX C—Pressure Check Diagram..................................36

APPENDIX D—Quick Motor Test Procedure......................37-39

APPENDIX E—Variable-Speed Condensing Furnace Duct Static

and Blower Operation.............................................................40-44

APPENDIX F—Quick Reference Information...........................45

APPENDIX G—Thermostat Staging Algorithm...................46-47

This guide uses your expertise and observations to lead you to the

INSTRUCTIONS

trouble spot as efficiently as possible. This is only intended as a guide and should not be used blindly. Your experience and expertise are of high value when troubleshooting this unit. Do not disregard all of your instincts.

The microprocessor furnace control was designed with diagnostic capabilities built in. LEDs are used to flash a fault code which will lead you to 1 of the subsections as listed in the Index.

You should ALWAYS begin in the START HERE subsection (see Index for page number) which will guide you to the appropriate subsection where a minimal number of steps will be used to correct the problem. If you are very experienced at how this furnace operates and you suspect the problem is either the blower motor, inducer motor,or furnace controlboard, youcan use the quick motor test procedure at the end of the troubleshooting guide to isolate the problem or direct you to appropriate section in main troubleshooting guide.

Once in a subsection, read the statement or question. A statement will have a number in the "GO TO" column. Do whatever the statement says, then proceed to step indicated in the "GO TO" column.

If the step is a question (a question will have a number in the "YES" or "NO" column), answer it "YES" or "NO." If the answer is "YES," go to step indicated in "YES" column. If the answer is "NO," go to step indicated in "NO" column.

Let’s try our guide out using the EXAMPLE section below, and see how it works. Suppose that the problem is a defective low-pressure switch (for example will not make). This is an internal problem and cannot simply be seen. We go to the START HERE section to Step 1. Additional Service Tools are available for current variable speed condensing furnaces. The Advanced Product Monitor Kit KGAFP0101APM includes a harness and diskette that allows communication with the control board through a personal computer (RS-485 adapter required). The ICM Motor Simulator Kit KGASD0101FMS is a plug-in device to help trooubleshoot ICM inducer and blower motors and control boards. Reference price pages for current kit numbers.

SEQUENCE OF OPERATION

Furnace control must be grounded for proper operation, or control will lock out. Control is grounded through green wire routed to gas valve and burner box screw.

Using schematic diagram (see Appendix A), follow sequence of operation through different modes. This furnace has a new control system. Read and follow wiring diagram carefully. NOTE: If 115-v power supply to furnace or blower access panel switch is interrupted during a call for heat, blower operates at low-heat speed for 60 sec when power is restored before heating cycle is resumed.

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

Book 1 4 Tab 6a 8a

PC 101 Catalog No. 535-754 Printed in U.S.A. Form 58MVP-8SM Pg 1 9-99 Replaces: 58MVP-6SM

Page 2

EXAMPLE

Start Here Section

STEP ACTION YES NO GO TO

1. Step 1 tells us to record status of LEDs 1-4 and go to Step 2. — — 2

Step 2 asks the question, "Are any LEDs flashing?". If low-pressure switch was defective, a low-

pressure switch fault code would be flashing, so the answer is "YES." We go to Step 5. Step 5 asks the question, "Is RED LED2 flashing?". If low-pressure switch was defective, a low-

pressure switch fault code would be flashing, so the answer is "NO". We go to Step 7.

7. Step 7 tells us to go to low-pressure switch fault subsection. — — INDEX

53 —

67 —

Step 1—Self-Test Mode

The control center goes through a brief self test whenever 115-v or 24-v power is interrupted. The self test takes approximately 2 sec to complete. After power is restored, red (microprocessor) LED briefly comes on. Thengreen LEDcomes onfor 1sec, followedby 1 sec where both yellow and green LEDs are on. During this time, the microprocessor is checking itself.

Step 2—Heating Mode

When thermostat calls for heat, R-W/W1 circuit closes.

1. Prepurge period—Theinducer motor is turned onand slowly

comes up to speed. When low-pressure switch closes, inducer motor RPM is noted by microprocessor, and a 25 sec prepurge period begins. The RPM is used to evaluate vent system resistance. This evaluation is then used to determine required RPM necessary to operate inducer in low-heat mode.

NOTE: The heat cycle can start in either high or low heat. If a high-heat cycle is initiated, the inducer continues increasing its speed after low-pressureswitch closes. When high-pressure switch closes, inducer motor RPM is noted by microprocessor before the 25 sec prepurge period begins. The RPM is used to evaluate vent system resistance. This evaluation is then used to determine required RPM necessary to operate inducer in high-heat mode.

2. Humidifier (HUM)—The HUM terminal is energized when-

ever the inducer prepurge period is completed.

3. Ignitor warm up—At end of prepurge period, the hot surface

ignitor (HSI) is energized for a 17-sec HSI warm-up period.

4. Ignition sequence—After HSI ignitor warm-up period is

completed, the gas valve opens, permitting gasflow to burners where it is ignited. After 5 sec, the HSI is de-energized and a 2-sec flame-sensing period begins.

NOTE: The initial heat mode after 115-v or 24-v power interruption will be LOW HEAT. Low heat remains energized for 16 minutes before high heat is initiated, providing thermostat is still calling for heat.

After the initial cycle, the microprocessor evaluates the length of low- and high-heat operating times and calculates optimum length of low and high heat for next heat cycle. This accommodates the heat load requirement seen as a resultof thermostat operating time. See Appendix G for details on thermostat staging algorithm.

5. Flame sensing—When burner flame is sensed, the control

center holds gas valve open and begins blower on delay period.

NOTE: Ignition sequence repeats 3 additional times before a lockout occurs. Lockout automatically resets after 3 hr, or can be manually reset by turning 115-v or 24-v power off (not at thermostat) for 3 sec minimum, then turning on again.

6. Inducer speed reduction—If cycle starts in low heat, inducer

speed reduces slightly after the flame sense. If cycle starts in high heat, inducer speed increases 15 sec after flame sense. The reduction in speed in low heat is to optimize combustion for maximum efficiency.

7. Blower on delay—The blower starts 60 sec after flame sense

if cycle started in low heat or 35 sec after flame sense if cycle started in high heat.

NOTE: The blower starts at approximately 400-500 RPM. After 20 sec, the motor is turned offfor 1/10 of a sec where a coast down calibration is done to evaluate resistance of the conditioned air duct system. The microprocessor then determines blower RPM required to provide proper airflow for heating mode.

8. Electronic Air Cleaner—The EAC-1 terminal is energized

whenever the blower operates.

9. Blower offdelay—When thermostat issatisfied, the R-W/W1

signal is terminated, de-energizing gas valve (stopping gas flow to burners) and HUM terminal is de-energized.

The blower reduces its speed to low-heat RPM. The blower and EAC remain operating 90, 135, 180, or 225 sec (depending on blower offtime selection).The furnaceis factoryset for a 90 sec blower off delay.

10. Post purge—The inducer continues operating for 15 sec after

gas valve is de-energized.

Step 3—Heating Mode—Two Stage

The control center provides 2-stage heating using a single-stage thermostat. The control center maximizes comfort while optimizing efficiency to meet the demands of the conditioned area when a thermostat R-W/W1 signal is received.

If thermostat control over furnace staging is desired, a 2-stage thermostat can be used. When control center receives a thermostat R-W/W1 and R-W2 signal, high heat is energized and when R-W/W1 signal is received, low heat is energized. This method overrides microprocessor control of high or low heat.

NOTE: When using 2-stage thermostat operation with R-W/W1 and R-W2 signals, setup switch SW-2 MUST be in ON position.

The heat cycle operates as stated in Heating Mode section. To allow for greater comfort, a 2-stage thermostat control is

recommended when zone systems are used.

Step 4—Emergency Heat Mode NOTE: The furnace should not be operated in emergency heat

mode for extended periods of time. Operation is only recommended to provide heat until replacement components can be obtained or fault resolved.

In this mode, the microprocessor is bypassed and the motors operate at full speed with high-heat operation. The heat exchangers, motors, and electronics can be overstressed and may reduce the life of the components if operated for an extended period.

NOTE: No safeties are bypassed when using emergency heat mode.

Emergency heat mode can be selected using setup switch SW-4. SW-4 should be used when a fault condition exists or difficult to resolve problems occur. This allows heating until the fault can be corrected.

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In emergency heat mode, the normal heat mode outlined in Heating Mode section is not followed. The following sequence will occur:

When thermostat calls for heat, the R-W/W-1 circuits close.

1. Prepurge period—The inducer motor is turned on IMMEDI-

ATELY operating at maximum speed, closing low- and high-pressure switches. Prepurge begins 25 sec after highpressure switch closes.

2. Blower on—The blower motor is turned on IMMEDIATELY

and slowly increases to maximum speed as soon as a call for heat is received. No blower calibration occurs.

3. Electronic Air Cleaner—The EAC-1 terminal does not

operate in emergency heat mode.

4. Humidifier—The HUM terminal is energized IMMEDI-

ATELY.

5. Ignitor warm up—The HSI is energized for a 17 sec

warm-up period after prepurge period is completed.

6. Ignition sequence—After HSI warm-up period has com-

pleted, the gas valve is energized, permitting gas flow to burners where it isignited. After 5sec, theHSI isde-energized and a 2-sec flame-sensing period begins.

NOTE: Emergency heat mode only operates in high heat.

7. Flame sensing—When burner flame is sensed, control center

holds gas valve open. If burner flame is not sensed, control center de-energizes gas valve and ignition sequence is repeated.

NOTE: Ignition sequence repeats 3 additional times before lockout occurs. Lockout automatically resets after 3 hr, or can be manually reset by turning 115-v or 24-v power off (not at thermostat) for 3 sec minimum, then turning on again. Fault codes will not flash in emergency heat mode.

8. Blower offdelay—When thermostat issatisfied, the R-W/W1

signal is terminated, de-energizing gas valve (stopping gas flow to burners) and HUM terminal is de-energized. In addition, blower stops immediately.

9. Post purge—Post purge does NOT occur. The inducer stops

immediately.

Step 5—Cooling Mode

When thermostat calls for cooling, the R-G and R-Y/Y2 circuits close.

1. Cooling unit—The cooling unit starts when thermostat R-Y

signal is received.

2. Blower on—The control center starts blower immediately

when it receives an R-Y/Y2 and R-G signal. The blower starts at approximately 400-500 RPM. After 20 sec, the blower is turned off for 1/10 of a sec where a coast down calibration is done to evaluate resistance of the conditioned air duct system. The microprocessor then determines blower RPM required to provide selected cooling airflow.

NOTE: In cooling mode, themicroprocessor adjusts blower RPM to operate at 400 CFM per ton as selected on the A/C setup switches. Airflow will be reduced to 340 or 315 CFM per ton, depending on board style (See Fig. 1), when a dehumidification demand exists. See Air Conditioning Setup Switches section in Installation, Start-Up and Operating Instructions for details. There is also a chart on schematic in Appendix A.

NOTE: If Y/Y2 thermostat lead is not connected to furnace control center, blower motor operates in continuous fan speed and indoor coil freeze-up may occur.

3. Electronic Air Cleaner—The EAC-1 terminal is energized

whenever blower operates.

4. Cooling unit—The cooling unit stops when thermostat R-Y

signal is terminated.

5. Blower off delay—When thermostat is satisfied, the R-Y/Y2

and R-G signals are terminated, and blower remains operating for 90 sec. On newer style control boards (See Fig. 1), the blower airflow will drop by 21 percent during the off-delay period when the DE jumper is connected. The DE jumper is only removed to enable the DEHUM input for use with a thermidistat or humidistat for dehumidification purposes.

Step 6—Heat Pump Mode

When furnace is operating in heat pump heating mode, R-Y/Y2 and R-G circuits are closed energizing heat pump, and blower operates at cooling speed. When heat pump defrost is required, R-W/W1 circuits close starting gas heat cycle, and blower adjusts to low-heat speed.

1. Prepurge period—Theinducer motor is turned onand slowly

NOTE: The heat cycle can start in either high or low heat. If a high-heat cycle is initiated, inducer continues increasing its speed after low-pressure switch closes. When high-pressure switch closes, inducer motor RPM is noted by microprocessor before the 25 sec prepurge period begins. The RPM is used to evaluate vent system resistance. This evaluation is used to determine required RPM necessary to operate inducer in high-heat mode.

2. Humidifier—The HUM terminal is energized whenever in-

ducer prepurge period is completed.

3. Ignitor warm up—After prepurge period, HSI is energized

for 17 sec.

4. Ignition sequence—After HSI warm-up period is completed,

the gas valve is energized, permitting gas flow to the burners where it is ignited. After 5 sec, the HSI is de-energized and a 2-sec flame-sensing period begins.

5. Flame sensing—When burner flame is sensed, control center

holds gas valve open. If burner flame is not sensed, control center de-energizes gas

valve and ignition sequence is repeated.

6. Blower off period—Ten sec after gas valve is energized, the

blower stops for 25 sec to allow heat exchangers to warm up.

7. Blower on delay—After blower off period, blower starts.

8. Electronic Air Cleaner—The EAC-1 terminal is energized

whenever blower operates.

9. Inducer speed reduction—If cycle starts in low heat, inducer

10. Call for heat terminated—When the call for heat is satisfied,

the R-W/W1 signal is terminated, de-energizing gas valve (stopping gas flow to burners) and HUM terminal is deenergized.

a. R-W/W1 signal terminated with R-Y/Y2 and R-G still

present—The blower changes its speed to cooling RPM.

Page 4

SEC-2

SEC-1

W/W1 Y/Y2 HUMRG

24V

W2 Com

DEHUM

SEC-2

SEC-1

DEHUM

W/W1 Y/Y2 HUMRG

24V

W2 Com

DE CONNECTION

WITHOUT DE

CONNECTION

Fig. 1—Variable Speed Furnace Control

b. R-W/W1 with R-Y/Y2 and R-G signals terminated—

The blower continues to operate completing a normal blower off delay.

11. Post purge—The inducer continues operating for 15 sec after

gas valve is de-energized.

Step 7—Continuous Fan Mode

1. Operating with continuous fan only. a. Call for continuous fan—The thermostat closes R-G

circuit.

b. Blower on—The blower starts immediately.

NOTE: The continuous fan speed is the same as low-heat speed unless it is field adjusted to another desired airflow. See Continuous Fan Setup Switches section in Installation, Start-Up, and Operating Instructions for details. There is also a chart on schematic diagram shown in Appendix A.

c. Electronic Air Cleaner—The EAC-1 terminal is ener-

gized whenever blower operates, regardless of operating mode.

2. Operating with continuous fan (R-G) and call for heat (R-W/W1) is received—Same as heat pump mode except blower on delay is 10 sec less than the heat mode. After call for heat (R-W/W1) is terminated, the blower remains operating at low-heat speed for selected blower off delay before resuming continuous fan speed.

3. Operating with continuous fan (R-G) and call for cooling (R-Y/Y2) is received—See Cooling Mode section. After call

WITH DE

CONNECTION

A98293

for cooling (R-Y/Y2) is terminated, the blower remains operating at cooling speed for 90 sec before resuming continuous fan speed.

Step 8—Component Test

All components are functionally operated except gas valve with component test feature.

This feature helps diagnose a system problem in case of a component failure.

NOTE: Setup switch SW-1 MUST be in OFF position or Fault Code 22 (setup error) will occur.

NOTE: NO thermostat signal may be present at control center, and all blower time delay off periods must be completed.

To initiate component test feature, proceed with the following:

1. Leave 115-v power to furnace turned on.

2. Remove main furnace door.

3. Remove blower access panel.

4. Turn setup switch SW-6 to ON position.

5. Manually close blower access panel door switch.

On some models, blower access paneldoor switch opens only 24-v power to control center. No component operation can occur. The 115-v power is still present at control center, transformer, inducer motor, and main blower motor. Caution must be taken when manually closing this switch for service purposes. Failure to follow this warning could result in personal injury or death.

Page 5

When items 1-5 have been completed, the following will occur:

1. The control center goes through a brief self test. This self test takes approximately 2 sec to complete. After door switch is closed, red (microprocessor) LED briefly comes on. Then green LED comes on for 1 sec, followed by 1 sec where both green and yellow LEDs are on. During this time, the microprocessor is checking itself.

2. Inducer motor operates for 20 sec at low speed, operates 20 sec at high speed, then turns off.

3. Hot surface ignitor is energized for 15 sec, then de-energized.

4. Main blower motor operates for 20 sec at low speed, operates for 20 sec at high speed, then turns off.

5. After component operation test is completed, 1 or more fault codes (11, 22, 41, or 42) will flash. See service label on back of main furnace door or Fig. 1 for explanation of fault codes.

NOTE: To repeat component test, turn setup switch SW-6to OFF and then back to ON.

After component test, perform the following:

1. Release blowerpanel access door switch and turn setup switch SW-6 to OFF position.

2. If applicable, replace blower access panel and check LED status by removing plug in blower access panel.

3. Reinstall main furnace door if all LEDs are off, indicating furnace is ready to operate when a signal from thermostat is received.

Step 9—Bypass Humidifier Mode

When setup switch SW-3 BPH is in ON position, RPM calculated for low heat is multiplied by 1.15 for all furnace model sizes. This compensates for increased return-air temperature caused by bypassed air supply.

standard humidistat to do dehumidification since the contacts open on high humidity, thus removing the 24-v signal to initiate dehumidification.

On the older style variable speed furnace controls, a field supplied relay is required betweenthe thermidistator humidistatcontrol and furnace. The relay coil is connected between DHUM output on the thermidistat control and C humidistat output and C

OM terminal on the furnace control or the

OM terminal on the furnace control. Its

normally closed contact is connected between R and DEHUM terminals on the furnace control. (See Fig. 1 and Fig. 2). When a dehumidify demand exists, relay is de-energized, and normally closed contacts supply 24-v to the furnace DEHUM terminal. As a result, the furnace control reduces the blower airflow by 15 percent to 340 CFM per ton during continuous fan or cooling operation.

On newer style variable speed furnace controls, a field supplied relay IS NOT required. The DEHUM output on the thermidistat control or the humidistat output is connected directly to the DEHUM terminal on the furnace control. In addition, the DE jumper located next to the DEHUM terminal must be removed to enable the DEHUM input. (See Fig. 1 and Fig. 3). When a dehumidify demand exists, the furnace control reduces the blower airflow by 21 percent to 315 CFM per ton during continuous fan or cooling operation.

VARIABLE-SPEED

THERMIDISTAT

24 VAC HOT

DEHUMIDIFY

DHUM

CONDENSING

FURNACE

DEHUM

VARIABLE-SPEED

THERMIDISTAT

24 VAC HOT

DEHUMIDIFY

24 VAC COMM

Fig.2—Without DE Connection

DHUM

CONDENSING

FURNACE

DEHUM

Com

A98294

Step 10—Dehumidification Mode

A dehumidification input is provided via a 1/4-in. male quickconnect terminal labeled DEHUM, located next to the transformer secondary connections. The DEHUM input acts differently depending on which style of variable speedfurnace control you have.

The older style variable speed furnace control (shown in Fig. 1) DOES NOT have a DE connection while the newer style variable speed furnace control (shown in Fig. 1) has a DE connection. The newer style variable speed furnace control is expected to be available by mid 1998. Both of these variable speed furnace controls function the same except the DEHUM logic is reversed. This logic reversal has come about from historical use of a

DE

NOTE 1

24 VA C COMM

Fig. 3—With DE Connection

NOTE 1 - Remove DE Connection To Enable DEHUM Input

Com

A98295

This blower speed reduction compensates for high humidity conditions during cooling operation on all furnace model sizes. Reference Thermidistat™ Control Installation, Start-up, and Operating Instructions for further details.

Step 11—Zone Mode

When setup switch SW-5 MZ is in ON position, blower motor control is the same as above except with the following exceptions:

1. While bloweris operatingin either low heat or continuous fan, the coast down calibration is performed once a minute to update blower RPM for zone damper position changes during a given cycle.

NOTE: Boards with date codes of 9506 or later will not perform a coast down calibration if blower pulse width to blower motor is greater than 60 percent. This prevents nuisance faults from occurring when a high continuous fan CFM has been selected.

2. While blower is operating in either high heat or cooling, blower pulse width to blower motor is frozen when blower RPM is within 10 percent of calculated blower RPM for 5 sec.

Page 6

START HERE—If a problem exists, the service technician should always begin troubleshooting here.

STEP ACTION YES NO GO TO

Remove furnace door first. DO NOT REMOVE BLOWER ACCESS PANEL! Record status of LED’s

1-4. See Service Label/Fault Code Instructions (Fig.4).

2. Are any LEDs flashing? 53 —

3. Are any LEDs on solid? (Solid means ON continuously.) 4 8 —

4. Go to page number indicated in Index for LEDs 1, 2, 3, or 4 ON SOLID. — — INDEX

5. Is RED LED2 flashing? 67 —

6. Go to page number indicated in Index for RED LED2 FLASHING. — — INDEX

7. Go to page number indicated in Index for subsection covering fault code being flashed. — — INDEX

8. Is power on? (DO NOT cycle power to unit). 10 9 —

9. Turn power on. —— 20

10.

11. Does problem appear to be low cooling airflow? 12 13 —

12. Go to page number indicated in Index for subsection covering NOT ENOUGH COOLING AIRFLOW. — — INDEX

13. Make sure thermostat is calling for heat. — — 14

14. Make sure thermostat fan control is in AUTO position if equipped. — — 15

15. Observe operation of furnace for 20 minutes or until fault occurs. — — 16

16. Does a fault occur? 717 —

17. Is temperature rise below range specified on rating plate when unit is running in high fire? 18 19 —

18.

19. Does furnace operate properly? 31 28 —

20.

21. Disconnect R thermostat lead, then wait until blower motor stops. — — 22

22. Are any LEDs flashing? 24 23 —

23. Are any LEDs on solid? (Solid means ON continuously.) 4 25 —

24. Is RED LED2 flashing? 67 —

25. Put setup switch SW-1 in ON position. — — 26

26.

27. Are LEDs 3 and 4 flashing a Fault Code 11? 29 30 —

28.

29. Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS. — — INDEX

30. Go to page number indicated in Index for subsection covering first fault code flashed. — — INDEX

31. Disconnect the R thermostat lead, then wait until blower motor stops. — — 32

32. Put setup switch SW-1 in ON position. — — 33

33.

34. Are LEDs 3 and 4 flashing a Fault Code 11? 35 30 —

35.

Remove blower access panel and depress door switch. Use a piece of tape to hold switch closed. Wait a few sec for self test before proceeding to next step.

Go to page number indicated in Index for subsection covering HIGH FIRE TEMPERATURE RISE TOO LOW (COLD BLOW).

Remove blower access panel and depress door switch. Use a piece of tape to hold switch closed. Wait a few sec for self test before proceeding to next step.

Record fault codes listed in fault history.

NOTE: Read fault codes until they repeat. The last fault code that occurred will flash first followed by the lowest number fault code. (EXAMPLE: 13, 13, 44)

Go to page number indicated in Index for subsection covering NO OPERATION WITH NO FLASHING FAULT CODE.

Record fault codes listed in fault history.

NOTE: Read fault codes until they repeat. The last fault code that occurred will flash first followed by the lowest number fault code. (EXAMPLE: 13, 13, 44)

Go to page number indicated in Index for the CLEANUP AND START-UP INSTRUCTIONS. If this problem persists on an intermittent basis, replace furnace control board. If problem still persists on an intermittent basis after replacing furnace control board, contact your distributor.

—— 2

—— 11

— — INDEX

—— 21

—— 27

— — INDEX

—— 34

— — INDEX

Page 7

SERVICE

LED CODE

RED LED1 ON RED LED2 ON

YELLOW LED3 ON GREE N LE D 4 ON RED LED2 FLAS HING

EACH OF THE FOLLOWING STATUS CODES IS A TWO DIGIT NUMBER WITH THE FIRST DIGIT DETERMINED BY NUMBER OF FLASHES OF THE YELLOW LED AND THE SECOND DIGIT DETERMINED BY NUMBER OF FLASHES OF THE GREEN LED.

11 NO FAULT IN RECENT HISTORY DISPLAY - Indicates no faults have occurred within last five cycles.

To rea d recent fault history put setup switch "SW-1" in th e "ON" position. To clear rec ent fault history, put setup switch "SW-1" in the "ON" position and jumper thermostat terminals "R", "W/W1", and "Y/Y2" sim ultaneously until an "11" is flashed.

12 BLOWER CALIBRATION LOCKOUT - Indi ca t es RPM calc ulated for low heat wa s less than 250 RPM

or greater than 1300 RPM on two successive attempts. Auto reset after three hours. Reset power and refer to fault #44 section.

13 LIMIT SWITCH LOCKOUT - Indicates the occurrence of 10 successive limit trips during high heat

or three successive limit trips during low heat. Auto reset after three hours. Check for: - Improper or misaligned limit and/or limit shield.

- Improper high or low heat gas input adjustment.

- Stuck high heat solenoid in gas valve.

14 IGNITION LOC KO UT - Control will auto-reset after three hours. Refer to #34. 21 INVALID MODEL SELECTION - Indicates model plug is missing or incorrect. See wiring diagram

for correct connector jumper location.

22 SETUP ERROR - Indicates setup switch "SW-1" or SW-6" is positioned improperly. The following

combinations will cause the fault.

- Th ermostat call with "SW-1" "ON" .

- Th ermostat call with "SW-6" "ON" .

-"SW-1" and "SW-6" both "ON" togeth er.

23 INVALID BLOWER AIRFLOW SELECTION - Indicates improper "A/C" or "CF" switch setting. The 042

and 14 units can deliver 1-1/2 to 3-1/2 tons A/C and 600 to 1400 CFM for continuous fan. The 060 and 20 unit can deliver 2 to 5 tons A/C and 800 to 2000 CFM for continuous fan. If code is flashing unit will default to closest allowable airflow.

24 SECONDA RY VOLTAGE FUSE IS OPEN

Check for: - Short circuit in secondary voltage (24V) wiring.

31 HIGH PRESS URE SWITCH FAULT - Indicates high pressure switch is closed at call, or in low heat,

or fails to close after call, or opens in high heat. Check for: - Plugged condensate drain.

- Water in vent piping, possibly sagging pipe.

- Improper pressure switch wiring or pressure switch tubing connections.

- Failed or "Out-of-Cali bration" pr essure switch es.

32 LOW PRESSUR E SWITCH FAULT - Indi cates low p ressure switc h is closed at call, or fails to close

after call, or opens during operation. Check for: - Plugged condensate drain.

- Water in vent piping, possibly sagging pipe.

- Improper pressure switch wiring or pressure switch tubing connections.

- Failed or "Out-of-Cali bration" pr essure switch es.

33 LIMIT OR FLAME ROLL-OUT SWITCH IS OPEN - Indicates the limit, rollout switch or auxiliary limit

switch is open or the un it is operat ing in high heat only m ode due to t wo successive low he at limit trips. Check for: - Imp r oper or misaligned limit and/o r limit shield.

- Impro per low heat gas input a djustment.

- Stuck h igh heat solenoid in gas valve.

Furnace is operating in emergency heat. The microprocessor has malfunctioned. To reset: Put setup switch " position and jumper thermostat terminals " the door switch pushed in and power to the unit "

OFF

setup switch in the " Furnace is operating in high heat. Furnace is operating in low heat. Line voltage polarity is reversed.

" position. If

STATUS

", "

LED2

reappea rs replace m ain control board.

SW-1

W/W1

", and "

Y/Y2

" simultaneously with

". Disconnect jumper and place

" in the "ON"

A99243a

Page 8

34 IGNITION PROVING FAULT - Control will try three more times before a lockout #14 occurs.

Check fo r: - G as v a lve de fec ti ve o r g a s va lv e t urned "OFF ".

- Defective Hot Surface Ignitor - Manual valve shut-off.

- Low inlet gas pressure - Flame sensor must be ungrounded.

- Gre e n wire MU ST b e connected to furnace sheet meta l.

- Proper flame sense microamps (.5 microamps D.C. minimum, 4.0 - 6.0 nominal in HIGH HEAT)

- Inadequate flame carryover or rough ignition. - Control ground continuity

- Oxid e b u ildup on flame sensor (clean with f ine steel wool.)

41 BLOWER OUTSIDE VALID SPEED RANGE - Indicates the blower is not operating at the calculated

RPM. If this fault occurs in conjunction with fault #44 check wiring to motor otherwise refer to the trouble-shooting guide.

42 INDU CER OU TSIDE VALID SPEED RANGE - Indicates the inducer is not operating at the

calculated RPM, or has not started within 10 seconds after a call for heat. Check wiring to motor otherwise refer to the trouble-shooting gu ide.

43 PRESSURE SWITCH CALIBRATION FAULT- Indicates the low and high pressure switch "make"

points during high heat pur g e are not w ithin the ca libration range. Check for: - Plugged condensate drain.

- Water in vent piping, possibly sagging pipe.

- Improper pressure switch wiring or pressure switch tubing connections.

- Failed or "Out of Calibration" pressure switches.

44 BL OWER CALI BRATIO N FAULT - Indicates the calculated blower speed is below 250 or above

1300 RPM. Unit will default to low o r high heat mode if possible. If this fault occurs in conjunction with fault #41 check wiring to motor otherwise refer to the trouble-shooting guide. If this fault occurs by it se lf che c k for und e rsize d duc twork, or exces siv e st a tic ca u s ed by a d ir ty fil te r , o r closed registers.

STATUS CODE EXAMPLE

RED LED1

EMER HEAT

SETUP SW,(SW1-8)

OFF

1 23456

YELLOW LED3

HIGH HEAT

GREEN LED4

LOW HEAT

OFF

321

OFF

1 2

3 4

RED LED2 MICROPROCESSOR MALFUNCTION

FUSE

DEHUM

COUN T TH E NO.

OF FLASHES

(4)

24 V

COUNT THE NO.

OF FLASHES

(2)

42 FAULT

INDUCER OUTSIDE VALID

SPEED RANGE

GRY/Y2W/W1

COMPONENT TEST

To in itiate the component test sequence, shut "OFF" the room ther mostat o r d isconnect the "R" thermostat lead. Put setup switch "SW-6" in the "ON" position to start the component test sequence. Once initiated the main board will turn "ON" the inducer motor-low speed, inducer motor-high speed, hot surface ignitor, blower motor-low speed, and blower motor-high speed for 15-20 seconds each. When component test is completed one or more of the following codes will flash. Gas Valve and Humidifier will not be turned on. CODE DESCRIPTION 11

Indicates inducer and blower m oto r tes ted OK. Visual check of hot surface ignitor re quired.

SETUP ERROR

BLOWER OUTSIDE VALID SPEED RANGE -

- Sam e as code 22 above. Indicates blower motor failed test. Check blower, wiring,

and control center.

INDUCER OUTSIDE VALID SPEED RANGE -

Indicates inducer motor failed test. Chec k inducer,

wiring and control center. To repeat component test turn se tup switch "SW-6" "OFF" and then back "ON". After component test is completed put setup switch "SW-6" in the "OFF" posit ion and reconnect the "R" thermostat lead.

320624-101 REV. J

→Fig. 4—Service Label/Fault Code Instructions

HUM

A99243

A99243b

Page 9

IMPROPER OPERATION WITH NO FLASHING FAULT CODE—Generally, this indicates there is no power to furnace control board.

STEP ACTION YES NO GO TO

1. Make sure power is on. —— 2

Remove blower access panel and depress door switch. Use a piece of tape to hold switch closed.

Wait a few sec for self test before proceeding to next step.

3. Make sure thermostat is calling for heat. — — 4

4. Make sure thermostat fan control is in AUTO position if equipped. — — 5

5. Check fuses, breakers, or manual disconnects to be sure they are correctly set. — — 6

6. Does 120-v wiring match unit wiring schematic? 9 7 —

7. Fix problem. —— 8

8. Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS. — — INDEX

9. Do you have 120 vac at primary leads P1 and P2 on furnace control board? 14 10 —

10. Do you have 120 vac to furnace control board? 11 12 —

11. Check all 120-vac connections at furnace control board. If necessary, replace furnace control board. — — 8

12. Turn power off. —— 13

13. Check continuity of power supply leads and door switch if wired with 120 vac. — — 7

14. Do you have 24v between SEC-1 and SEC-2 on furnace control board? 19 15 —

15. Turn power off. —— 16

16. Do you have continuity across door switch? 17 18 —

17. Replace transformer. If transformer fails again, replace transformer and furnace control board. — — 8

18. Replace door switch. —— 8

19. Do you have 24v between R and Com on furnace control board? 21 20 —

20. Replace furnace control board. —— 8

21. Do you have 24v between W/W1 and Com on furnace control board? 24 22 —

22. Check to see that thermostat is calling for heat. — — 23

23. You have a defective thermostat or a break in the wiring between thermostat and furnace. — — 7

24. Does furnace respond to the call for heat? 27 25 —

25. Turn power off. —— 26

26.

27.

28. Disconnect BROWN wire to gas valve GV. — — 29

29.

30. Disconnect humidifier lead from HUM terminal on furnace control board. — — 31

31.

32. There is a direct short in wiring to humidifier solenoid coil, or short is inside humidifier solenoid coil. — — 7

33.

34.

35. Disconnect BROWN wire to gas valve GV. — — 36

36.

37. Replace gas valve. —— 8

38.

39. Disconnect humidifier lead from HUM terminal on furnace control board. — — 40

40.

Press down on microprocessor chip and make sure it is properly seated to furnace control board. If it is, replace furnace control board.

Does furnace keep repeating the following cycle? Inducer motor MTR1 runs, inducer motor MTR1 stops, furnace control board goes through a self-test sequence, blower motor runs for 1 minute, and then cycle repeats.

Does furnace still alternately cycle inducer motor, go through a self test, and then run blower motor as described in Step 27?

There is a direct short in either the pressure switch circuits, gas valve GV, or wiring to gas valve GV. If hot surface ignitor comes on during the cycle, short is in gas valve or wiring to gas valve.

Does furnace ever abruptly shut down with no fault code, no inducer post purge, no blower off delay, and then restart heating cycle?

Does furnace still abruptly shut down with no fault code, no inducer post purge, no blower off delay, and then restart heating cycle?

Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS. If problem persists on an intermittent basis, replace furnace control board. If problem still persists after replacing furnace control board, contact your distributor.

Does furnace still abruptly shut down with no fault code, no inducer post purge, no blower off delay, and then restart heating cycle?

—— 3

—— 7

28 34 —

30 37 —

33 32 —

—— 7

35 38 —

39 37 —

— — INDEX

33 32 —

Page 10

NOT ENOUGH COOLING AIRFLOW—Generally, this indicates the Y/Y2 thermostat lead is not properly connected.

STEP ACTION YES NO GO TO

Remove blower access panel and depress door switch. Use a piece of tape to hold switch closed.

Wait a few sec for self test before proceeding to next step. Make sure thermostat is calling for cooling. If thermostat lead G is not connected, jumper across

thermostat terminals R and G.

3. Make sure thermostat fan control is in AUTO position if equipped. — — 4

4. Do you have 24v across Y/Y2 and Com on furnace control board? 8 5 —

You have a defective thermostat, or a break in wiring between thermostat and furnace, or the Y/Y2

thermostat terminal is not wired to thermostat.

6. Fix problem. —— 7

7. Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS. — — INDEX

Are air conditioning select switches A/C set to proper tonnage as required by condensing unit? (See

Table 1.) Set air conditioning select switches A/C for proper tonnage as required by condensing unit. (See

Table 1.)

10. Disconnect the G thermostat lead or jumper if used. — — 11

11. Does blower motor turn off in 90 sec when G thermostat lead is disconnected? 12 13 —

12. Replace furnace control board. —— 7

13. Observe operation of furnace in cooling mode for 8 minutes. — — 14

14. Does furnace operate properly in cooling mode? 15 16 —

Make sure outdoor unit is properly charged. If it is, go to page number indicated in Index for

15.

16. Does furnace abruptly go through a self-test sequence as blower comes up to speed? 17 24 —

17. Do you have less than 17 vac between R and Com on furnace control board? 18 24 —

18. Do you have less than 90 vac between P1 and P2 on furnace control board? 19 20 —

19.

20. Disconnect the R thermostat lead. —— 21

21. Do you have less than 17 vac between R and Com on furnace control board? 22 23 —

22. Replace transformer. —— 7

23.

24.

CLEANUP AND START-UP INSTRUCTIONS. If problem persists on an intermittent basis, replace furnace control board. If problem still persists after replacing furnace control board, contact your distributor.

Make sure the wire gage between main fuse box and furnace complies with wire size specification in Installation, Start-Up, and Operating Instructions.

Check the thermostat wire gage between furnace and thermostat, and furnace and outdoor unit. It is recommended that AWG No. 18 color-coded copper thermostat wire be used for lengths up to 100 ft. For wire lengths over 100 ft, use AWG No. 16 wire.

Press down on microprocessor chip and make sure it is properly seated to furnace control board. If it is, replace furnace control board.

—— 2

—— 3

—— 6

10 9 —

—— 7

— — INDEX

—— 6

AIR CONDITIONER

(TONS) Default

1-1/2 600 ON OFF OFF X X X — — —

2 800OFFONOFFXXXXXX

2-1/2 1000 ON ON OFF XXXXXX

3 1200 OFF OFF ON XXXXXX

3-1/2 1400 ON OFF ON XXXXXX

4 1600 OFF ON ON — — — X X X 5 2000 ON ON ON — — — X X X

X—Indicates allowable selection.

AIRFLOW

(CFM)

1200 or

Table 1—Air Conditioning (A/C) Airflow Setup Switch Position

A/C SWITCH POSITION ALLOWABLE FURNACE MODEL SETUP

A/C-1 A/C-2 A/C-3 040 060 080 080 100 120

2000

OFF OFF OFF

3 Tons

1200 CFM

3 Tons

1200 CFM

3 Tons

1200 CFM

5 Tons

2000 CFM

5 Tons

2000 CFM

5 Tons

2000 CFM

Page 11

HIGH-FIRE TEMPERATURE TOO LOW—Generally, this indicates the HIGH/LOW solenoid in gas valve GV has failed or furnace is extremely underfired.

STEP ACTION YES NO GO TO

1. Turn power off and remove blower access panel. Make sure thermostat is NOT calling for heat. — — 2

Depress door switch. Use a piece of tape to hold switch closed. Wait a few sec for self test before

proceeding to next step.

3. Set thermostat to call for heat or jumper R and W/W1 thermostat terminals. — — 4 When GREEN LED4 is ON solid, clock low-fire gas rate. You have 16 minutes on this first call for

heat. On propane installations, check manifold pressure. When YELLOW LED3 is ON solid, clock high-fire gas rate. On propane installations, check manifold

pressure.

6. Is high-fire rate approximately same as low-fire rate? 7 11 — Do you have 24 vac across gas valve terminal HI and Com on furnace control board during high

fire? You have an open wire or bad terminal on BROWN wire from furnace control board to gas valve

GV. Repair it or replace the harness.

9. Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS. — — INDEX

10. Replace gas valve. —— 9

11. Is high-fire rate within 2% of that specified on rating plate? 13 12 —

12.

13. Check outdoor condensing unit for operation during heating cycle. — — 14

14.

15. Check return-air ducts in unheated spaces for leaks. — — 9

Ensure gas inlet pressure and burner orifices are correct, then adjust gas valve to proper rate. If it cannot be adjusted to proper rate, replace gas valve.

Check temperature rise with blower door in place. Temperature rise should be mid-range or slightly higher than midpoint of range stated on furnace rating plate. If return temperature is below 60°F, condensation may form on heat exchangers. If left uncorrected, failure will result.

—— 3

—— 5

—— 6

10 8 —

—— 9

—— 15

LEDs 1, 2, 3, or 4 ON SOLID (SOLID means on continuously.)

• RED LED1 ON SOLID indicates furnace is operating in emergency heat.

• RED LED2 ON SOLID indicates microprocessor has malfunctioned or secondary voltage to furnace control board is low.

• YELLOW LED3 ON SOLID indicates furnace is operating in high fire.

• GREEN LED4 ON SOLID indicates furnace is operating in low fire.

STEP ACTION YES NO GO TO

1. Turn power off and remove blower access panel. — — 2

2. Turn power on and depress door switch. Use a piece of tape to hold switch closed. — — 3

3. Jumper R and W/W1 thermostat terminals on furnace control board. — — 4

4. Is RED LED1 ON? 59 —

5. Is setup switch SW-4 labeled EMER. HEAT in ON position? 6 7 —

6. Put setup switch SW-4 labeled EMER. HEAT in OFF position. — — 8

7. Replace furnace control board. —— 8

8. Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS. — — INDEX

9. Disconnect jumper wire across R and W/W1 thermostat terminals. — — 10

10. Is RED LED2 ON? 11 32 —

11. Do you have less than 17 vac between R and Com on furnace control board? 12 19 —

12. Do you have less than 90 vac between P1 and P2 on furnace control board? 13 15 —

13.

14. Fix problem. —— 8

15. Disconnect R thermostat lead. —— 16

16. Is RED LED2 ON? 17 18 —

17. Replace transformer. —— 8

18.

19. Disconnect all thermostat leads from furnace control board. — — 20

20. Put setup switch SW-1 in ON position and jumper R, W/W1, and Y/Y2 thermostat terminals. — — 21

21. Does RED LED2 turn OFF? 22 7 —

22. Put setup switch SW-1 back in OFF position. — — 23

23. Turn power off and reconnect thermostat leads to furnace control board. — — 24

24. Turn power on. —— 25

25. Does RED LED2 turn back ON? 26 36 —

26. Disconnect all thermostat leads from thermostat control board. — — 27

27.

Make sure wire gage between main fuse box and furnace complies with wire size specification in Installation, Start-Up, and Operating Instructions.

Check thermostat wire gage between furnace and thermostat, and furnace and outdoor unit. It is recommended that AWG No. 18 color-coded copper thermostat wire be used for lengths up to 100 ft. For wire lengths over 100 ft, use AWG No. 16 wire.

Put setup switch SW-1 in ON position and jumper R, W/W1, and Y/Y2 thermostat terminals simultaneously until RED LED2 turns OFF.

—— 14

—— 28

Page 12

28. Put setup switch SW-1 back in OFF position. — — 29

29. Jumper R and W/W1 thermostat terminals. — — 30

30. Does RED LED2 turn back ON? 731 —

31. Install isolation relays in the W/W1 and Y/Y2 circuits per Fig. 5 in Appendix B or replace thermostat. — — 8

32. Was RED LED2 ON before you started Step 1? 34 33 —

33.

34.

35.

36.

37.

38. Replace gas valve. —— 8

39. Isolate humidifier with a separate 24-vac supply or replace humidifier solenoid coil. — — 14

40. Observe operation of furnace through a 4 minute cooling cycle. Does RED LED2 turn ON? 41 47 —

41. Disconnect all thermostat leads from furnace control board. — — 42

42.

43. Put setup switch SW-1 back in OFF position. — — 44

44. Reconnect only outdoor unit to Y/Y2 and Com terminals on furnace control board. — — 45

45. Jumper R and Y/Y2 thermostat terminals. — — 46

46. Does RED LED2 turn back ON? 34 31 —

47.

Solid YELLOW LED3 indicates furnace is in high fire and solid GREEN LED4 indicates furnace is in low fire.

Check outdoor unit contactor. Failure to pull in can cause excessive current draw on low-voltage circuit. This can be intermittent and may require extended operation to repeat problem. Isolating outdoor unit may solve problem. (See Fig. 6 in Appendix B.)

Check thermostat wire gage between furnace and outdoor unit. It is recommended that AWG No. 18 color-coded copper thermostat wire be used for lengths up to 100 ft. For wire lengths over 100 ft, use AWG No. 16 wire.

Observe operation of furnace through a 20 minute heat cycle. Try to pinpoint where in cycle RED LED2 turns ON.

Go to step indicated below if RED LED2 turns ON when 1 of the following events occur: — — —

• When gas valve is energized. —— 38

• When HSI is energized. —— 39

• When high-pressure switch HPS makes during transition from low to high fire. — — 38

• RED LED2 never turns ON. —— 40

Put setup switch SW-1 in ON position and jumper R, W/W1, and Y/Y2 thermostat terminals simultaneously until RED LED2 turns OFF.

Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS. If problem persists on an intermittent basis, replace furnace control board. If problem still persists on an intermittent basis after replacing furnace control board, contact your distributor.

—— 8

—— 35

—— 14

—— 37

—— 43

— — INDEX

RED LED2 FLASHING—Indicates line voltage polarity is reversed.

STEP ACTION YES NO GO TO

Turn power off, remove blower access panel, and disconnect all thermostat leads from furnace con-

trol board.

2. Turn power on and depress door switch. Use a piece of tape to hold switch closed. — — 3

3. Is RED LED2 flashing? 64 —

4. Replace furnace control board, date code 9405 or later. — — 5

5. Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS. — — INDEX

6. Do you have 120 vac across L2 and chassis ground? 7 8 —

7. Line voltage polarity is reversed. Fix problem. — — 5

8. Replace furnace control board. —— 5

—— 2

Page 13

Fault Code 11

NO FAULT IN RECENT HISTORY DISPLAY—This indicates 1 of the following:

• No faults have occurred in the last 5 previous cycles and setup switch SW-1 is in ON position.

• The fault history can be cleared by jumpering R, W/W1, and Y/Y2 thermostat leads simultaneously while setup switch SW-1 is in ON position.

• Component test was successfully completed and setup switch SW-6 is in ON position.

STEP ACTION YES NO GO TO

1. Remove blower access panel and depress door switch. Use a piece of tape to hold switch closed. — — 2

2. Is setup switch SW-1 in ON position? 3 5 —

3. Put setup switch SW-1 in OFF position. — — 4

4. Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS. — — INDEX

5. Is setup switch SW-6 in ON position. 6 7 —

6. Put setup switch SW-6 in OFF position. — — 4

Jiggle setup switches SW-1 and SW-6 back and forth. If Fault Code 11 continues to flash, replace

furnace control board.

—— 4

Fault Code 12

BLOWER CALIBRATION LOCKOUT—This fault indicates that blower motor speed calculated for low heat is either less than 250 RPM or greater than 1300 RPM on 2 successive attempts at calibration. Control will auto-reset in 3 hours.

STEP ACTION YES NO GO TO

Turn power off, wait 30 sec, and then restore power. Reset thermostat. Observe operation of fur-

nace through 1 heating cycle.

NOTE: Blower access panel must be in place.

2. Does only Fault Code 44 flash? 40 6 —

The problem is excessive restriction in the air delivery system. Check filters and ductwork. Use Ap-

pendix E to evaluate.

4. Fix problem. —— 5

5. Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS. — — INDEX

6. Does Fault Code 44 flash twice followed by Fault Code 41? 9 7 —

7. Does a different fault occur? 839 —

8. Go to page number indicated in Index for fault code flashed. — — INDEX

9. Turn power off and remove blower access panel. — — 10

10. Are all pins and wire leads intact on connectors between furnace control board and blower motor. 11 4 —

11.

12.

13. Does blower motor turn on and come up to speed (400-500 RPM) before fault code flashes? — 20 —

14.

15.

16. Replace furnace control board. —— 5

17.

→18.

Depress door switch. Use a piece of tape to hold switch closed. Wait a few sec for self test before proceeding to next step.

Disconnect all thermostat leads from furnace control board and jumper R and W/W1 thermostat terminals.

Disconnect jumper wire across R and W/W1 thermostat terminals, turn power off, and then restore power. Wait a few sec for self test before proceeding to next step.

Check RPM feedback line. To do this, connect a DC voltmeter across terminals PL3-2 ORANGE (+) and PL3-3 VIOLET (–), then put setup switch SW-6 for COMPONENT TEST in ON position. Does voltage across ORANGE and VIOLET wires change between states as shown below?

• State 1—OFF (12.0—12.5 vdc)

• State 2—LOW (10.7—11.7 vdc)

• State 3—HIGH(9.7—10.7 vdc)

Connect a DC voltmeter across ORANGE (+) and VIOLET (-) wires at connector PL13, then repeat the COMPONENT TEST by turning setup switch SW-6 OFF and then back ON. Do you see approximately the same DC voltages across ORANGE and VIOLET wires that you saw in Step 15?

Replace entire blower motor or blower control module attached to the blower motor. If you replace the blower control module go to step 44. Always inspect failed motor for water damage. If present, find source of water and fix. Check A-coil and/or humidifier.

—— 2

—— 4

—— 12

—— 13

—— 15

16 17 —

18 19 —

—— 4

Page 14

19.

20. Remove tape from door switch and turn power off at main disconnect. — — 21

21. Does blower wheel rub against blower housing? 4 22 —

22. Does blower wheel turn freely?

23. Is blower wheel firmly mounted on motor shaft? 25 4 —

→24.

25. Disconnect jumper wire across R and W/W1 thermostat terminals. — — 26

26.

27. Do you have 120v between B1 and B2 on furnace control board? 28 4 —

28. Do you have 120v between BLACK and WHITE power leads at blower motor MTR2? 30 29 —

29.

30.

31.

32.

33.

34. Put setup switch SW-6 for COMPONENT TEST in OFF position. — — 35

35.

36.

37.

38.

39.

40.

41.

42. Jumper R and G thermostat terminals. Observe operation of furnace for next 30 sec. — — 43

43.

You have an open wire or bad terminal on either the ORANGE or VIOLET wire between connectors PL13 and PL3. Repair it or replace blower harness(es).

Turn power back on. Depress door switch. Use a piece of tape to hold switch closed. Wait a few sec for self test before proceeding to next step.

You have an open wire or bad terminal on either the BLACK or WHITE wire between furnace control board and blower motor MTR2.

Check blower ON/OFF line. To do this, connect a DC voltmeter across terminals PL3-1 RED (+) and PL3-5 BLUE (-), then put setup switch SW-6 for COMPONENT TEST in ON position. Does voltage across RED and BLUE wires change between states as shown below?

• State 1—OFF (-0.1 — 0.1 vdc)

• State 2—ON (9.0 — 10.0 vdc)

Disconnect PL3 from furnace control board and connect a DC voltmeter across terminals PL3-1 (+) and PL3-5 (-) on furnace control board, then repeat COMPONENT TEST by turning setup switch SW-6 OFF and then back ON. Does voltage across PL3-1 and PL3-5 change between states as shown below?

• State 1—OFF (-0.1 — 0.1 vdc)

• State 2—ON (11.0 — 12.0 vdc)

Connect a DC voltmeter across RED (+) and BLUE (-) wires at connector PL13 then repeat COMPONENT TEST by turning setup switch SW-6 OFF and then back ON. Do you see approximately the same DC voltages across RED and BLUE wires that you saw in Step 30?

You have an open wire or bad terminal on either the RED or BLUE wire between connectors PL13 and PL3. Repair it or replace blower harness(es).

Check blower PW line. To do this, connect a DC voltmeter across terminals PL3-1 RED (+) and PL3-4 YELLOW (-), then put setup switch SW-6 for COMPONENT TEST in ON position. Does voltage across the RED and YELLOW wires change between states as shown below?

• State 1—OFF (-0.1 — 0.1 vdc)

• State 2—LOW (2.5 — 3.0 vdc)

• State 3—HIGH (7.0 — 7.5 vdc)

Disconnect PL3 from furnace control board and connect a DC voltmeter across terminals PL3-1 (+) and PL3-4 (-) on furnace control board then repeat COMPONENT TEST by turning setup switch SW-6 OFF and then back ON. Does voltage across PL3-1 and PL3-4 change as shown below?

• State 1—OFF (-0.1 — 0.1 vdc)

• State 2—LOW (3.0 — 4.0 vdc)

• State 3—HIGH (9.0 — 10.0 vdc)

Connect a DC voltmeter across RED (+) and YELLOW (-) wires at connector PL13 then repeat COMPONENT TEST by turning setup switch SW-6 OFF and then back ON. Do you see approximately the same DC voltages across RED and YELLOW wires that you saw in Step 35?

You have an open wire or bad terminal on either the RED or YELLOW wire between connectors PL13 and PL3. Repair it or replace blower harness(es).

Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS. If problem persists on an intermittent basis, replace blower motor. If problem still persists on an intermittent basis after replacing blower motor, contact your distributor.

Turn power off and remove blower access panel. Depress door switch. Use a piece of tape to hold switch closed. Wait a few sec for self test before proceeding to next step.

Disconnect all thermostat leads from furnace control board. If blower motor is running, wait until it stops.

Approximately 20 sec after energizing G thermostat terminal, does blower motor pause briefly (less than1/2 sec?)

Note:You can verify this pause using a clamp-on ammeter on BLACK power lead to blower motor MTR2.

—— 5

—— 4

—— 27

—— 5

32 31 —

18 16 —

34 33 —

—— 5

37 36 —

18 16 —

18 38 —

—— 5

— — INDEX

—— 41

—— 42

318 —

Page 15

Wait at least 5 minutes after disconnecting line voltage from equipment before opening blower motor to prevent electric shock which can cause personal injury or death.

→44. Remove tape from door switch and turn power off at main disconnect. ——45 →45. Disconnect PL10 from blower assembly. — — 46 →46. Remove control box assembly from blower shelf and position out of the way. — — 47 →47. Remove blower assembly from furnace. — — 48

→48.

→49.

→50.

→51.

→52. Did the motor pass the resistance check? 53 55 — →53. Does blower wheel turn freely with blower control module removed? 54 55 —

→54.

→55.

Disconnect both multi-pin connectors from blower control module attached to the blower motor. Be sure to depress release latches on connectors or they may get damaged.

Remove two 1/4-in. hex head bolts from blower control module attached to blower motor. DO NOT REMOVE TORX HEAD SCREWS located next to 1/4-in. hex head bolts.

Carefully lift blower control module off blower motor. Depress latch on internal connector to disconnect blower control module from motor portion of blower motor. DO NOT PULL ON WIRES. GRIP PLUG ONLY.

When blower control module is completely detached from blower motor, verify with standard ohmmeter that the resistance from each motor lead in motor plug to unpainted motor end plate is greater than 100k ohms. Then verify motor windings are not shorted or open by measuring resistance between each combination of pins in motor plug (there are three different combinations, pin 1-2, pin 2-3, and pin 1-3). Resistance should be approximately equal across each combination of pins.

Replace blower control module. Inspect failed blower control module for water damage. If present, find source of water and fix. Check A-coil and/or humidifier.

Replace entire blower motor including blower control module. Inspect blower control module for water damage. If present, find source of water and fix. Check A-coil and/or humidifier.

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——51

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Fault Code 13

LIMIT SWITCH LOCKOUT—This fault indicates the limit switch has tripped 10 times in a row in high fire or 3 times in a row in low fire during a call for heat. Control will auto-reset in 3 hr.

NOTE: After 2 low-fire limit trips, the control is locked into high-heat mode; however, a third low-heat cycle can be forced due to excessive

restriction in air delivery system. NOTE: Boards with date codes of 9506 or later will lock into high-heat mode after 2 low-fire limit trips and CANNOT be forced into a third

low-heat cycle. Therefore, units with these boards can only lock out if the limit switch trips 10 times in a row in high fire during a call for heat.

STEP ACTION YES NO GO TO

Turn power off and remove blower access panel. Disconnect all thermostat leads from furnace con-

trol board.

2. Depress door switch. Use a piece of tape to hold switch closed. — — —

3. Put setup switch SW-1 in ON position. — — 4

Is a Fault Code 44 present in the fault history.

NOTE: Read fault codes until they repeat. The last fault code that occurred will flash first followed by the lowest number fault code. (EXAMPLE: 13, 13, 44)

5. Put setup switch SW-1 in OFF position. — — 42

Does furnace have proper limit switch, limit shield, blower baffle (if used), and rear air baffle (if

used)? If so are limit switch, limit shield, and heat exchangers properly aligned?

7. Replace limit switch. —— 9

8. Replace furnace control board. —— 9

9. Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS. — — INDEX

10. Put setup switch SW-2 in ON position. — — 11

11. Jumper R and W/W1 thermostat terminals on furnace control board. — — 12

12.

13.

14.

15. Replace or rewire personality connector. — — 9

Is furnace considerably overfired (10% or more)? Clock input rate. Do not use manifold pressure method unless using propane.

Ensure gas inlet pressure and burner orifices (natural or propane) are correct. Then adjust gas valve to proper rate per Installation, Start-Up, and Operating Instructions. If it cannot be adjusted to proper rate, replace gas valve.

Is the personality connector PL5 properly wired per furnace model sizing chart in upper left-hand corner of wiring schematic?

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46 5 —

10 48 —

13 14 —

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50 15 —

Page 16

16. Does the installation have a bypass humidifier? 17 30 —

17. Is setup switch SW-3 in ON position? 19 18 —

18. Put setup switch SW-3 in ON position. — — 9

19.

20. Disconnect jumper wire across R and W/W1 thermostat terminals and wait until blower stops. — — 21

21. Remove blower access panel and put setup switch SW-3 in OFF position. — — 22

22.

23. Is the temperature rise in Step 22 more than 10°F higher than the temperature rise in Step 19? 24 8 —

24. Disconnect jumper wire across R and W/W1 thermostat terminals and wait until blower stops. — — 25

25. Remove blower access panel and put setup switch SW-3 in ON position. — — 26

26.

27. Is temperature rise from bypass greater than 15°F? 28 29 —

28. The bypass is oversized. Adjust damper or replace with properly sized bypass. — — 9

29. Disconnect jumper wire across R and W/W1 thermostat terminals and wait until blower stops. — — 30

30. Does the installation have modulating zone dampers? 31 51 —

31. Is setup switch SW-5 in ON position? 33 32 —

32. Put setup switch SW-5 in ON position? — — 9

33. Jumper R and W/W1 thermostat terminals on furnace control board. — — 34

34.

35.

36.

Cycle furnace with blower access panel in place and record temperature rise across furnace 6 minutes after main burner ignition.

Cycle furnace with blower access panel in place and record the temperature rise across return air duct before and after the bypass.

Does blower recalibrate every minute? Check by monitoring DC voltage across terminals PL3-1 RED (+) and PL3-5 BLUE (-). If DC voltage momentarily goes down to 0 vdc approximately every 60 sec after first blower calibration, then blower is recalibating properly.

Disable modulating zone damper system with all dampers in open position except bypass damper. If the installation is equipped with a bypass damper, it should be in the closed position.

Put setup switch SW-2 in OFF position. Disconnect jumper wire across R and W/W1 thermostat terminals and reset the power. Reconnect jumper wire across R and W/W1 thermostat terminals and monitor manifold gas pressure while observing furnace operation for 10 minutes.

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35 8 —

—— 36

—— 37

NOTE: Blower access panel must be in place.

37. Does a Fault Code 33 flash? 39 38 —

38.

39.

40. Replace gas valve. —— 9

41.

The problem is cause by the modulating zone damper system. Install a 2-stage thermostat and let the zone system modulate gas flow. If you still have a problem, check the zone manufacturer’s installation and Troubleshooting Guide for corrective action.

While monitoring manifold pressure in Step 36, did it drop to low-fire manifold pressure during lowfire operation?

Replace blower motor and belly band.

NOTE: Torque belly band screw to 80 in.lb (6.7 ft. lb).

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49 40 —

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WARNING: DO NOT OVERTIGHTEN!

42. Jumper R, W/W1, and W2 thermostat terminals on furnace control board. — — 43

43.

44.

45. Disconnect jumper wire across R, W/W1, and W2 thermostat terminals and wait until blower stops. — — 6

46. Excessive restriction of airflow during locked in high-fire mode caused lockout. — — 47

47.

48. Fix problem. —— 9

49. Is temperature rise within ±10°F of midpoint of rise range? 51 41 —

50. Is temperature rise within ±10°F of midpoint of rise range? 51 16 —

51. Turn power off and install a temperature probe in front of limit switch button. — — 52

52.

53.

Is furnace considerably overfired (10% or more)? Clock input rate. Do not use manifold pressure method unless using propane.

Ensure gas inlet pressure and burner orifices (natural or propane) are correct. Then adjust gas valve to proper rate per the Installation, Start-Up, and Operating Instructions. If it cannot be adjusted to proper rate, replace gas valve.

Relieve restriction. Check all dampers, filters, and return-air grilles for blockage. Put setup switch SW-1 in OFF position.

Turn power on and cycle unit. Does limit switch open at a temperature at least 10°F below temperature setpoint for limit switch. (EXAMPLE: The setpoint is 220°F, but switch opens at a temperature below 210°F.)

The problem may be related ot poor air distribution. Add turning varies, more supply-air openings, or more return-air openings. Use Appendix E to evaluate.

44 45 —

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753 —

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Page 17

Fault Code 14

IGNITION LOCKOUT—This fault indicates the system failed to ignite gas and prove flame in 4 attempts. Control will auto-reset in 3 hr. This fault could also indicate the gas valve relay GVR on furnace control board is stuck closed or there is a miswire/short to gas valve wiring.

STEP ACTION YES NO GO TO

Turn power off and set thermostat to OFF position. Turn power back on and wait a few sec for self

test before proceeding to next step.

2. Does Fault Code 14 flash? 36 —

3. There is a miswire or short to gas valve wiring. — — 4

4. Fix problem. —— 5

5. Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS. — — INDEX

6. Does a different fault occur? 78 —

7. Go to page number indicated in Index for the fault code flashed. — — INDEX

8. Remove blower access panel and depress door switch. Use a piece of tape to hold switch closed. — — 9

9. Jumper R and W/W1 thermostat terminals. — — 10

10. Does Fault Code 14 start flashing when low-pressure switch LPS makes? 11 12 —

11. Replace furnace control board. —— 5

12. Does a different fault occur? 713 —

13. Disconnect jumper wire across R, and W/W1, 2 thermostat terminals and wait until blower stops.. — — 14

14. Jumper R, W/W1, and W2 thermostat terminals on furnace control board. — — 15

15. Does Fault Code 14 start flashing when high-pressure switch HPS makes? 16 17 —

16. The BLUE and GREEN wires to gas valve GV are reversed. — — 4

17. Disconnect jumper wire across R, W/W1, and W2 thermostat terminals and wait until inducer stops. — — 18

18. Put setup switch SW-1 in ON position. — — 19

19.

20. Cycle furnace several times to check for intermittent operation. — — 21

21.

22.

Is a Fault Code 34 present in fault history?

NOTE: Read fault codes until they repeat. The last fault code that occurred will flash first followed by the lowest number fault code. (EXAMPLE: 14, 14, 34)

Check that the GREEN wire is properly connected to furnace sheet metal and clean flame sensor withfine sandpaper.

Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS. If problem persists on an intermittent basis, replace furnace control board. If problem still persists on an intermittent basis after replacing furnace control board, contact your distributor.

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20 22 —

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— — INDEX

Fault Code 21

INVALID MODEL SELECTION—Personality connector PL5 is either not connected or jumpered wrong.

STEP ACTION YES NO GO TO

1. Turn power off and remove blower access panel. — — 2

2. Is personality connector PL5 properly wired per furnace model size chart on wiring diagram? 5 3 —

3. Replace or rewire personality connector. — — 4

4. Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS. — — INDEX

5. Depress door switch. Use a piece of tape to hold switch closed. — — 6

6. Make sure thermostat is calling for heat or jumper R and W/W1 thermostat terminals. — — 7

7. Will furnace operate while flashing fault code? 9 8 —

8. Replace furnace control board. —— 4

9. Are personality plug wires making good connection? 10 11 —

10.

11. Fix poor terminal connection or replace personality connector. — — 4

The furnace will operate acceptably; however, a model selection circuit failure has occurred and furnace control board is defaulting to last valid model selection. Board replacement is recommended but not necessary. This fault code will flash continuously.

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Page 18

Fault Code 22

SETUP ERROR—This fault indicates that setup switches SW-1 or SW-6 are ON when they should be OFF. The following combinations will cause the fault:

• Thermostat call with SW-1 ON.

• Thermostat call with SW-6 ON.

• SW-1 and SW-6 both ON together.

STEP ACTION YES NO GO TO

1. Turn power off and remove blower access panel. — — 2

Make sure thermostat is NOT calling for heating or cooling. Disconnect all thermostat terminal leads

to make sure.

3. Is setup switch SW-1 in ON position? 4 6 —

4. Put setup switch SW-1 in OFF position. — — 5

5. Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS. — — INDEX

6. Is setup switch SW-6 in ON position? 7 8 —

7. Put setup switch SW-6 in OFF position. — — 5

8. Replace furnace control board. —— 5

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Fault Code 23

INVALID BLOWER AIRFLOW SELECTION—This fault indicates improper A/C or CF switch setting. The -14 units can deliver sufficient airflow for 1-1/2 to 3-1/2 tons A/C and 600 to 1400 CFM for continuous fan. The -20 unit can deliver sufficient airflow for 2 to 5 tons A/C and 800 to 2000 CFM for continuous fan. If fault code is flashing, unit still operates, but it defaults to closest allowable airflow.

NOTE: Boards with date codes of 9506 or later will flash fault code and set continuous fan airflow to same airflow as A/C if continuous fan

is adjusted to a higher airflow than A/C setting.

STEP ACTION YES NO GO TO

1. Turn power off and remove blower access panel. — — 2

2. Are air conditioning select switches A/C set properly? (See Table 2.) 5 3 —

3. Set air conditioning select switches A/C for proper tonnage as required by condensing unit. — — 4

4. Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS. — — INDEX

5. Are continuous fan select switches CF set properly? (See Table 3.) 7 6 —

Set continuous fan select switches CF for desired airflow. This setting should normally be set to DE-

FAULT position unless a 2-speed AC/HP is part of system. Use Table 4 for reference on 2-speed AC/HP airflow requirements.

Are continuous fan select switches CF set to a higher airflow than air conditioning select switches

A/C? (See Tables 2 and 3.)

8. Is furnace a 100 size? 11 9 — The problem is in the A/C or CF selection circuit. The maximum cooling or continuous fan airflow for

this unit will be delivered.

10.

11.

12.

Jiggle A/C and CF switches back and forth. If fault code continues to flash, replace furnace control board.

The problem is in the A/C or CF selection circuit. The minimum cooling or continuous fan airflow for this unit will be delivered.

Jiggle A/C and CF switches back and forth. If fault code continues to flash, replace furnace control board.

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Page 19

Table 2—Air Conditioning (A/C) Airflow Setup Switch Position

AIR CONDITIONER

(TONS) Default

1-1/2 600 ON OFF OFF X X X — — —

2 800OFFONOFFXXXXXX

2-1/2 1000 ON ON OFF XXXXXX

3 1200 OFF OFF ON XXXXXX

3-1/2 1400 ON OFF ON XXXXXX

4 1600 OFF ON ON — — — X X X 5 2000 ON ON ON — — — X X X

X—Indicates allowable selection.

AIRFLOW

(CFM)

1200 or

2000

A/C SWITCH POSITION ALLOWABLE FURNACE MODEL SETUP

A/C-1 A/C-2 A/C-3 040 060 080 080 100 120

OFF OFF OFF

3 Tons

1200 CFM

Table 3—Continuous Fan (CF) Airflow Setup Switch Position

CONTINUOUS FAN

(CFM)

Default OFF OFF OFF 565* 515* 690* 690* 860* 1035*

600 ON OFF OFF X X X — — —

800 OFF ON OFF X X X X X X 1000 ON ON OFF X X X X X X 1200 OFF OFF ON X X X X X X 1400 ON OFF ON X X X X X X 1600 OFF ON ON — — — X X X 2000 ON ON ON — — — X X X

* Add 15% additional CFM when Bypass Humidifier switch SW-3 on control board is used. X—Indicates allowable selection.

CF SWITCH POSITION ALLOWABLE FURNACE MODEL SETUP

CF-1 CF-2 CF-3 040 060 080

3 Tons

1200 CFM

3 Tons

1200 CFM

5 Tons

2000 CFM

080

(5 Ton)

5 Tons

2000 CFM

100 120

5 Tons

2000 CFM

Table 4—Two-Speed AC/HP Airflow Requirements (CFM)

OUTDOOR UNIT CAPACITY 036 048 060

A/C Setting 3 Tons—1200 4 Tons—1600 5 Tons—2000

CF Setting 800 1000 1000

Fault Code 24

SECONDARY VOLTAGE FUSE IS OPEN—Indicates fuse is open and there is a short in low-voltage wiring.

STEP ACTION YES NO GO TO

1. Turn power off and remove blower access panel. — — 2

2. Is secondary voltage fuse blown? Check continuity to make sure. 5 3 —

3. Replace furnace control board. —— 4

4. Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS. — — INDEX

Disconnect all thermostat leads from furnace control board (including HUM terminal) and replace

secondary voltage fuse.

6. Depress door switch. Use a piece of tape to hold switch closed. — — 7

7. Does Fault Code 24 flash? 810 —

You have a short circuit in limit switch circuit. This includes limit switch, flame rollout switch, and

auxiliary limit switch.

9. Fix problem and replace secondary voltage fuse if necessary. — — 4

10. Jumper R and W/W1 thermostat terminals on furnace control board. — — 11

11. Does Fault Code 24 occur when W/W1 is energized? 12 16 —

12.

13.

14. Does Fault Code 24 occur when W/W1 is energized? 3 15 —

15. You have a short circuit in pressure switch circuit. — — 9

16. Does Fault Code 24 occur when low-pressure switch is energized? 17 20 —

17. Disconnect PL2 from furnace control board. — — 18

Disconnect jumper wire across R and W/W1 thermostat terminals and replace secondary voltage fuse.

Disconnect PL2 from furnace control board and jumper R and W/W1 thermostat terminals on furnace control board.

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Page 20

18.

19. The ORANGE wire from low-pressure switch LPS is shorting to ground. Replace or repair it. — — 9

20. Does Fault Code 24 occur when gas valve GV is energized? 21 28 —

21.

22.

23.

24. Disconnect PL1 from furnace control board. — — 25

25. Do you have continuity between BLUE wire and chassis ground? 26 3 —

26. The BLUE wire to gas valve GV is shorting to ground. Replace or repair it. — — 9

27. Replace gas valve GV. —— 4

28. Add a jumper across R and W2 thermostat terminals on furnace control board. — — 29

29. Does Fault Code 24 occur when high-pressure switch HPS is energized? 30 39 —

30.

31.

32. Does Fault Code 24 occur when high-pressure switch HPS is energized? 33 27 —

33. Disconnect PL1 from furnace control board. — — 34

34. Do you have continuity between BROWN wire and chassis ground? 35 36 —

35. The BROWN wire to gas valve GV is shorting to ground. Replace or repair it. — — 9

36. Disconnect PL2 from furnace control board. — — 37

37.

38. The BROWN wire from high-pressure switch HPS is shorting to ground. Replace or repair it. — — 9

39. Disconnect jumper wire across R, W/W1, and W2 thermostat terminals and wait until blower stops. — — 40

40. Jumper R, G, and Y/Y2 thermostat terminals on furnace control board. — — 41

41. Does Fault Code 24 occur when G and Y/Y2 are energized? 3 42 —

42.

43. Does Fault Code 24 occur during heating cycle? 44 45 —

44. You have a defective thermostat or a short circuit in wiring between thermostat and furnace. — — 9

45. Does Fault Code 24 occur during cooling cycle? 46 47 —

46. You have a defective thermostat or a short circuit in wiring between thermostat and outdoor unit. — — 9

47. Does problem usually occur in cooling mode? 48 49 —

48.

49. Reconnect humidifier and check for excessive current draw. — — 9

Do you have continuity between the N.O. (Normally Open) contact on low-pressure switch LPS and chassis ground?

Disconnect jumper wire across R and W/W1 thermostat terminals and replace secondary voltage fuse.

Disconnect BLUE wire to gas valve GV and jumper R and W/W1 thermostat terminals on furnace control board.

Does Fault Code 34 IGNITION PROVING FAULT occur? If not, Fault Code 24 should occur when BLUE wire is energized.

Disconnect jumper wire across R, W/W1, and W2 thermostat terminals and replace secondary voltage fuse.

Disconnect BROWN wire to gas valve GV and jumper R, W/W1, and W2 thermostat terminals on furnace control board.

Do you have continuity between the N.O. (Normally Open) contact on high-pressure switch HPS and chassis ground?

Reconnect all thermostat leads (except HUM terminal if used) to furnace control board and operate furnace in heating and cooling mode from thermostat.

Check outdoor unit contactor. Failure to pull in can cause excessive current draw on low-voltage circuit. This can be an intermittent problem.

19 3 —

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27 24 —

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38 3 —

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Fault Code 31

HIGH-PRESSURE SWITCH FAULT—This fault can occur under the scenarios shown below, keep in mind that whenever furnace control boardshuts unitdown, gasshuts offimmediately, inducer continues running for 15 sec, and if blower is running, it remains running at low-heat speed or reduces to low-heat speed for selected off delay.

• CALL FOR HEAT—If high-pressure switch HPS is made when a call for heat is initiated, furnace control board flashes Fault Code 31 until switch opens, then cycle begins.

• LOW HEAT

1. PREPURGE AND FIRST 45 SEC AFTER IGNITION—If high-pressure switch HPS makes during prepurge or just after ignition, furnace control board continues operating until burners are lit and inducer RPM is within 10% of calculated low-fire RPM. If high-pressure switch HPS remains made, furnace control board starts flashing Fault Code 31, shuts unit down, waits 2 minutes, stops flashing Fault Code 31, and restarts heating cycle.

2. STEADY-STATE—If high-pressure switch HPS makes during low heat, furnace control board starts flashing Fault Code 31, shuts unit down, waits 2 minutes, stops flashing Fault Code 31, and restarts heating cycle.

• HIGH HEAT

1. PREPURGE—If high-pressure switch HPS does not make within 45 sec after low-pressure switch LPS makes, furnace control board starts flashing Fault Code 31, shuts unit down, waits 2 minutes, stops flashing Fault Code 31, and restarts heating cycle.

If high-pressure switch HPS opens before ignition, furnace control board starts flashing Fault Code 31 and ramps inducer RPM up until high-pressure switch HPS remakes. When high-pressure switch HPS remakes, furnace control board stops flashing Fault Code 31 and continues heating cycle. If high-pressure switch HPS does not remake within 45 sec after opening, furnace control board continues flashing Fault Code 31, shuts unit down, waits 2 minutes, stops flashing Fault Code 31, and restarts heating cycle.

2. FIRST MINUTE AFTER IGNITION—If high-pressure switch HPS opens during first minute after ignition, furnace control board starts flashing Fault Code 31, shuts unit down, waits 2 minutes, stops flashing Fault Code 31, and restarts heating cycle.

3. STEADY-STATE—If high-pressure switch HPS opens during high heat, furnace control board starts flashing Fault Code 31 and ramps inducer RPM up until high-pressure switch HPS remakes. When high-pressure switch HPS remakes, furnace control board stops flashing Fault Code 31 and continues heating cycle. If high-pressure switch HPS does not remakewithin 45 sec after opening, furnace control board continues flashing Fault Code 31, shuts unit down, waits 2 minutes, stops flashing Fault Code 31, and restarts heating cycle.

4. HIGH FIRE TO LOW FIRE TRANSITION—When using a 2-stage thermostat and W2 is de-energized, high-pressure switch HPS must open within 45 sec. If high-pressure switch HPS does not open within 45 sec after W2 was de-energized, furnace control board starts flashing Fault Code 31, shuts unit down, waits 2 minutes, stops flashing Fault Code 31, and restarts heating cycle.

STEP ACTION YES NO GO TO

1. Turn power off, remove blower access panel, and disconnect R thermostat lead. — — 2

2. Turn power on and depress door switch. Use a piece of tape to hold switch closed. — — 3

3. Jumper R and W/W1 thermostat terminals on furnace control board. — — 4

4. Observe operation of furnace through 1 heating cycle. — — 5

5. Does fault occur again? 96 —

6. Does a different fault occur? 78 —

7. Go to page number indicated in Index for fault code flashed. — — INDEX

8. Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS. — — INDEX

9. Does fault occur within 5 sec after W/W1 is energized? 10 18 —

10.

11. Replace furnace control board. —— 8

12. Is high-pressure switch HPS wired correctly? 14 13 —

13. Rewire high-pressure switch HPS per wiring diagram. — — 8

14. Replace pressure switch assembly. — — 8

15. Do you have 24v between connector terminal PL2-4 and Com on furnace control board? 16 11 —

16. The main harness is miswired. —— 17

17. Fix problem. —— 8

18. Does fault occur during blower on delay period? 19 23

19. Turn power off and disconnect jumper wire across R and W/W1 thermostat terminals. — — 20

20.

21. Does Fault Code 14 start flashing when high-pressure switch HPS makes? 22 14 —

22. The BLUE and GREEN wires to gas valve GV are reversed. — — 17

23. Does fault occur during low fire after blower turns on? 24 29 —

24. Turn power off and disconnect jumper wire across R and W/W1 thermostat terminals. — — 25

Do you have 24v between the N.O. (Normally Open) contact on high-pressure switch HPS and Com on furnace control board?

Turn power on and wait several sec, then jumper R, W/W1, and W2 thermostat terminals on furnace control board.

12 15 —

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Page 22

25.

26.

27. Monitor slope manometer. Does pressure reading appear to be stable when fault occurs? 14 28 —

28. Check for a sag in vent pipe. If problem persists, replace inducer motor. — — 8

29. Disconnect jumper wire across R and W/W1 thermostat terminals and wait until blower stops. — — 30

30. Jumper R, W/W1, and W2 thermostat terminals on furnace control board. — — 31

31. Does high-pressure switch HPS make, then break several times at start of cycle before faulting out? 32 33 —

32. The problem is either a sag in vent pipe or a clogged drain trap or line. — — 17

33. Does fault occur before main burners ignite? 34 51 —

34.

35.

36.

37. Is inducer motor MTR1 rotating in direction indicated on inducer housing? 39 38 —

38. Replace inducer motor or inducer motor assembly. — — 8

39. Turn power off. —— 40

40. Is inducer wheel okay? 42 41 —

41. If possible, replace inducer wheel. Otherwise, replace inducer motor assembly. — — 8

42. Is there any frost build-up on combustion-air inlet? 43 44 —

43.

44. You have excessive restriction in combustion-air or vent pipe. — — 8

45. Turn power off and disconnect jumper wire across R, W/W1, and W2 thermostat terminals. — — 46

46.

47.

48. Turn power off. —— 49

49.

50.

51. Turn power off and disconnect jumper wire across R, W/W1, and W2 thermostat terminals. — — 52

52.

53.

54. Monitor slope manometer. Does pressure reading appear to be stable when fault occurs? 55 56 —

55.

56. Check for a sag in vent pipe. If problem persists, replace inducer motor. — — 8

Connect 1 side of a slope manometer with a tee to collector box pressure tap. Connect other side with a tee to gas valve air pressure fitting. Refer to pressure check diagram in Appendix C.

Turn power on and wait several sec, then jumper R and W/W1 thermostat terminals on furnace control board.

Do you have 24v between C (Common) on high-pressure switch HPS and Com on furnace control board?

The YELLOW wire to high-pressure switch HPS is not making good connection. Repair or replace it.

Do you have at least 1.90 in. wc pressure drop across heat exchangers when fault occurs? Determine this by connecting 1 side of slope manometer with a tee to collector box pressure tap. Connect other side with a tee to gas valve air pressure fitting. Refer to pressure check diagram in Appendix C.

The problem is caused by reversed vent and combustion-air pipes or some other moist air entering combustion-air pipe.

Turn power on and wait several sec, then jumper R, W/W1, and W2 thermostat terminals on furnace control board.

Do you have 24v between connector terminal PL2-4 and Com on furnace control board when fault occurs?

Do you have continuity across terminal PL2-4 and N.O. (Normally Open) contact on high-pressure switch HPS?

The BROWN wire from high-pressure switch HPS to furnace control board is not making good connection. Repair wire or replace harness.

Connect 1 side of a slope manometer with a tee to collector box pressure tap. Connect other side with a tee to gas valve air pressure fitting. Refer to pressure check diagram in Appendix C.

Turn power on and wait several sec, then jumper R, W/W1, and W2 thermostat terminals on furnace control board.

Replace pressure switch assembly. If problem persists, check wiring for an intermittent connection in high-pressure switch HPS circuit.

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36 35 —

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45 37 —

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11 48 —

14 50 —

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Page 23

Fault Code 32

LOW-PRESSURE SWITCH FAULT—This fault can occur under the scenarios shown below. Keep in mind that whenever the furnace control board shuts unit down, gas shuts off immediately, inducer continues running for 15 sec, and if blower is running it remains running at low-heat speed or reduces to low-heat speed for selected off delay.

• On propane installations when low gas pressure switch LGPS is open due to switch failure or low propane line pressure.

→

• CALL FOR HEAT—If low-pressure switch LPS is made when a call for heat is initiated, furnace control board flashes Fault Code 32 until switch opens, then cycle begins.

• LOW HEAT

1. PREPURGE—If low-pressure switch LPS does not make within 45 sec after call for heat is initiated, furnace control board starts flashing Fault Code 32, shuts unit down, waits 2 minutes, stops flashing Fault Code 32, and restarts heating cycle.

If low-pressure switch LPS opens before ignition, furnace control board starts flashing Fault Code 32 and ramps inducer RPM up until low-pressure switch LPS remakes. When low-pressure switch LPS remakes, furnace control board stops flashing Fault Code 32 and continues heating cycle. If low-pressure switch LPS does not remake within 45 sec after opening, furnace control board continues flashing Fault Code 32, shuts unit down, waits 2 minutes, stops flashing Fault Code 32, and restarts heating cycle.

2. STEADY-STATE—If low-pressure switch LPS opens during low heat, furnace control board starts flashing Fault Code 32, shuts unit down, waits 2 minutes, stops flashing Fault Code 32, and restarts heating cycle.

• HIGH HEAT

If low-pressure switch LPS opens before ignition, furnace control board starts flashing Fault Code 32, shuts unit down, waits 2 minutes, stops flashing Fault Code 32, and restarts heating cycle.

2. STEADY-STATE—If low-pressure switch LPS opens during high heat, furnace control board starts flashing Fault Code 32, shuts unit down, waits 2 minutes, stops flashing Fault Code 32, and restarts heating cycle.

STEP ACTION YES NO GO TO

1. Turn power off, remove blower access panel, and disconnect R thermostat lead. — — 2

2. Turn power on and depress door switch. Use a piece of tape to hold switch closed. — — 3

3. Is inducer motor MTR1 running? 45 —

4. Are inducer motor MTR1 and blower motor MTR2 running? 13 49 —

5. Jumper R and W/W1 thermostat terminals on furnace control board. — — 6

6. Observe operation of furnace through 1 heating cycle. — — 7

7. Does fault occur again? 11 8 —

8. Does a different fault occur? 910 —

9. Go to page number indicated in Index for fault code flashed. — — INDEX

10. Go to page number indicated in Index for CLEANUP AND STARTUP INSTRUCTIONS. — — INDEX

11. Does fault occur within 5 sec after a call for heat? 12 17 —

12.

13. Replace furnace control board. —— 10

14. Is low-pressure switch LPS wired correctly? 16 15 —

15. Rewire low-pressure switch LPS per wiring diagram. — — 10

16. Replace pressure switch assembly. — — 10

17. At start of cycle as inducer is ramping up, does low-pressure switch LPS make then break? 34 18 —

→18. Does fault occur after ignition but before the blower comes on? 55 54 —

19.

20. Do you have 24v between connector terminal PL2-1 and Com on furnace control board? 21 13 —

21. Turn power off. —— 22

22.

23. The YELLOW wire to low-pressure switch LPS is not making good connection. Repair or replace it. — — 10

24.

25. Is inducer motor MTR1 rotating in direction indicated on inducer housing? 28 26 —

26. Replace inducer motor or inducer motor assembly. — — 10

27. Fix problem. —— 10

28. Turn power off. —— 29

Do you have 24v between N.O. (Normally Open) contact on low-pressure switch LPS and Com on furnace control board?

Do you have 24v between C (Common) on low-pressure switch LPS and Com on furnace control board?

Double check continuity between C (Common) on low-pressure switch LPS and connector terminal PL2-1.

Do you have at least 0.95 in. wc pressure drop (0.75 in. wc on trophy unit) across heat exchangers when fault occurs? Determine this by connecting 1 side of a slope manometer with a tee to collector box pressure tap. Connect other side with a tee to gas valve air pressure fitting. Refer to pressure check diagram in Appendix C.

14 47 —

24 20 —

—— 23

35 25 —

Page 24

29. Is inducer blower wheel okay? 31 30 —

30. If possible, replace inducer blower wheel. Otherwise, replace inducer motor assembly. — — 10

31. Is there any frost build-up on combustion-air inlet? 32 33 —

32.

33. You have excessive restriction in combustion-air or vent pipe. — — 10

34. The problem is either a sag in vent pipe or a clogged drain trap or line. — — 27

35. Turn power off and disconnect jumper wire across R and W/W1 thermostat terminals. — — 36

36.

37.

38. Turn power off. —— 39

39.

→40.

41. Turn power off and disconnect jumper wire across R and W/W1 thermostat terminals. — — 42

42.

43.

44. Monitor slope manometer. Does pressure reading appear to be stable when fault occurs? 45 46 —

45.

46. Check for a sag in vent pipe. If problem persists, replace inducer motor. — — 10

47. Do you have 24v between connector terminal PL2-2 and Com on furnace control board? 48 13 —

48. The main harness is miswired. —— 27

49.

50. Does inducer motor MTR1 turn on? 19 51 —

51. Do you have less than 90 vac between I1 and I2 on furnace control board? 53 52 —

52.

53.

→54. Does the fault occur before ignition 45 sec after call for heat? 50 41 — →55. Check propane line pressure if using low gas pressure switch LGPS otherwise go to step 41. — — 27

The problem is caused by reversed vent and combustion-air pipes or some other moist air entering combustion-air pipe.

Turn power on and wait several sec, then jumper R and W/W1 thermostat terminals on furnace control board.

Do you have 24v between connector terminal PL2-2 and Com on furnace control board when fault occurs?

Do you have continuity across terminal PL2-2 and N.O. (Normally Open) contact on low-pressure switch LPS?

The ORANGE wire from low-pressure switch LPS to furnace control board is not making good connection or low gas pressure switch LGPS (when used) is open. Check propane line pressure if using LGPS otherwise repair wire or replace harness.

Connect 1 side of a slope manometer with a tee to collector box pressure tap. Connect other side with a tee to gas valve air pressure fitting. Refer to pressure check diagram in Appendix C.

Turn power on and wait several sec, then jumper R and W/W1 thermostat terminals on furnace control board.

Replace pressure switch assembly. If problem persists, check wiring for an intermittent connection in low-pressure switch LPS circuit.

Check Inducer PW line. To do this, disconnect PL7 from inducer motor and connect a DC voltmeter across terminals PL7-2 BROWN (+) and PL7-10 YELLOW (-) then run COMPONENT TEST by turning setup switch SW-6 ON. Does voltage across PL7-2 and PL7-10 change between states as shown below?

• State 1—OFF (-0.1 — 0.1 vdc)

• State 2—LOW (6.0 — 7.0 vdc)

• State 3—HIGH (10.5 — 11.5 vdc)

• State 1—OFF (-0.1 — 0.1 vdc)

• State 2—LOW (6.0 — 7.0 vdc)

• State 3—HIGH (10.5 — 11.5 vdc)

Make sure wire gage between main fuse box and furnace complies with wire size specification in Installation, Start-Up, and Operating Instructions.

—— 27

—— 37

13 38 —

16 40 —

—— 27

—— 43

—— 44

—— 10

26 13 —

—— 27

Fault Code 33

LIMIT SWITCH FAULT—This fault indicates the limit switch, rollout switch or auxiliary limit switch is open or unit is operating in high-heat only mode due to 2 successive low-heat limit trips.

STEP ACTION YES NO GO TO

1. Turn power off, remove blower access panel, and disconnect R thermostat lead. — — 2

2. Turn power on and depress door switch. Use a piece of tape to hold switch closed. — — 3

3. Is the fault code flashing? 11 4 —

4. Set thermostat to call for heat or jumper R and W/W1 thermostat terminals. — — 5

5. Observe operation of furnace for next 25 minutes. — — 6

6. Does fault occur again? 40 7 —

7. Does a different fault occur? 89 —

8. Go to page number indicated in Index for fault code flashed. — — INDEX

Page 25

9. Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS. — — INDEX

10.

11. Do you have 24v between terminals PL1-9 and C? 13 12 —

12. Replace furnace control board. —— 9

13. Do you have 24v between terminals PL1-11 and C? 12 15 —

14. You have an open RED wire or bad terminal in limit circuit. Repair or replace it. — — 9

15. Turn power off. —— 16

16. Do you have continuity across limit switch LS? 20 17 —

17. Wait for unit to cool then recheck for continuity across limit switch LS. — — 18

18. Do you have continuity across limit switch LS? 20 19 —

19. Replace limit switch. —— 9

20. Do you have continuity across flame rollout switch FRS? 28 21 —

21. Can flame rollout switch FRS be reset? 23 22 —

22. Replace flame rollout switch. —— 9

23.

24. Does flame rollout switch trip again? 26 25 —

25. Does a different fault occur? 89 —

26.

27. Fix problem. —— 9

28. Do you have continuity across auxiliary limit switch ALS? 14 29 —

29. Can auxiliary limit switch ALS be reset? 31 30 —

30. Replace auxiliary limit switch. —— 9

31.

32. Does fault occur again? 38 33 —

33. Does a different fault occur? 834 —

34. Is this unit in downflow or horizontal position? 35 9 —

35.

36. Does fault occur after blower stops? 37 9 —

37.

38.

39.

40. Does fault occur during low fire? 41 42 —

41.

42.

Consider this fault like a Fault Code 13 and go to page number indicated in Index for Fault Code

13.

Reset flame rollout switch FRS, turn power on, and observe furnace operation for (2) 15 minute cycles.

You have inadequate combustion-air supply. This may be caused by:

• Reversed vent and combustion-air pipes.

• Poor burner, manifold, or orifice alignment.

• Leak somewhere between primary and secondary heat exchangers.

• Leak in secondary heat exchanger.

• Internal restriction in coupling box or secondary heat exchanger.

Reset auxiliary limit switch ALS, replace blower access panel, turn power on, set thermostat to call for heat or jumper R and W/W1 thermostat terminals, and observe furnace operation for 15 minutes.

Disconnect R thermostat lead, wait for blower to stop, and continue to observe unit for 5 more minutes.

Increase blower off delay time to 225 sec by putting both setup switches SW-7 and SW-8 in ON position.

Does furnace have proper limit switch, limit shield, blower baffle (if used), rear air baffle (if used), and auxiliary limit switch? If so, are limit switch, limit shield, and heat exchangers properly aligned?

Change limit switch first. If problem still exists, replace auxiliary limit switch. One of these switches is out of calibration.

On the third burner cycle, unit will run in high-fire mode and flash fault code continuously. The unit is locked into high-fire-only mode. Verify the following before going to Step 10:

• If unit has a bypass humidifier, make sure setup switch SW-3 is in ON position.

• If unit is installed in a zone system, make sure setup switch SW-5 is in ON position.

• Check low-fire rate. Clock input rate. DO NOT use manifold pressure method unless using propane.

Verify the following before going to Step 10:

• If unit is installed in a zone system, make sure setup switch SW-5 is in ON position.

• Check high-fire rate. Clock input rate. DO NOT use manifold pressure method unless using

propane.

— — INDEX

—— 24

—— 27

—— 32

—— 36

—— 27

39 27 —

—— 9

—— 10

Page 26

Fault Code 34

IGNITION PROVING FAULT—This fault can indicate 1 of the following:

• Flame was not sensed during trial for ignition period. The control will repeat ignition sequence 3 more times before going into Fault 14—IGNITION LOCKOUT.

• The flame signal was lost after trial for ignition period.

• The flame signal was sensed while gas valve was de-energized. The inducer will run at full speed until fault is cleared.

STEP ACTION YES NO GO TO

Turn power off, remove blower access panel, and disconnect R thermostat lead from furnace con-

trol board.

2. Turn power on and depress door switch. Use a piece of tape to hold switch closed. — — 3 Make sure thermostat is NOT calling for heat and reconnect R thermostat lead to furnace control

board. Observe unit for 15 minutes. Does inducer motor ever turn on at full speed while furnace control board flashes Fault Code 34?

4. Replace furnace control board. Make sure it has a date code 9405 or later. — — 12 Disconnect R thermostat lead from furnace control board and jumper R and W/W1 thermostat termi-

nals on furnace control board.

6. Observe operation of furnace through 1 heating cycle. — — 7

7. Does fault occur again? 13 8 —

8. Does a different fault occur? 910 —

9. Go to page number indicated in Index for fault code flashed. — — INDEX

10. Disconnect jumper wire across R and W/W1 thermostat terminals. Does fault occur now? 11 12 —

11. Replace gas valve. —— 12

12. Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS. — — INDEX

13. Turn power off and disconnect jumper wire across R and W/W1 thermostat terminals. — — 14

14. Turn power on and wait several sec before proceeding to next step. — — 15

15.

16.

17. Replace furnace control board. —— 12

18. Check continuity in harness and ignitor. Replace defective component. — — 19

19. Fix problem. —— 8

20. Put setup switch SW-6 for COMPONENT TEST in OFF position. — — 21

21. Jumper R and W/W1 thermostat terminals on furnace control board. — — 22

22.

23. Turn power off. —— 24

24.

25.

26. Does gas valve open and allow gas to flow? 28 27 —

27. Are all manual gas cocks in ON position? 11 19 —

28. Do main burners ignite? 30 29 —

29.

30. Do main burners stay on? 40 31 —

31. Turn power off and disconnect jumper wire across R and W/W1 thermostat terminals. — — 32

32. Connect a DC microammeter in series with flame sensor wire. — — 33

33.

34. Is DC current below 0.5 microamps? 36 35 —

35.

36.

37. Is current near typical value? 39 38 —

38. Replace electrode. —— 12

39. Will main burners ignite and stay on? 12 17 —

40. Do you have combustion pulsations? 41 47 —

Check hot surface ignitor. To do this, put setup switch SW-6 for COMPONENT TEST in ON position. Does ignitor glow orange/white hot by end of 15-sec warm-up period?

Disconnect PL4 from furnace control board. Connect an AC voltmeter across PL4-1 and PL4-2 on furnace control board. Repeat COMPONENT TEST by turning setup switch SW-6 OFF and then back ON. Do you see 120 vac across PL4-1 and PL4-2 during 15-sec warm-up period?

Connect an AC voltmeter across BLUE and GREEN wires to gas valve GV. Does gas valve GV receive 24v?

Do you have continuity across the following connections:

• PL1-2 and BLUE wire at gas valve GV.

• PL1-7 and GREEN wire at gas valve GV.

The BLUE or GREEN wire from furnace control board to gas valve GV is not making good connection. Repair wire(s) or replace harness.

Check for the following:

• Inadequate flame carryover or rough ignition.

• Low inlet gas pressure.

Turn power on and wait several sec then jumper R and W/W1 thermostat terminals on furnace control board.

Check connections and recheck current. If current is near typical value and control will not stay on, replace furnace control board.

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

—— 2

45 —

—— 6

20 16 —

18 17 —

26 23 —

17 25 —

—— 12

—— 19

—— 34

—— 12

—— 37

Page 27

41. Make sure perforated disks are in combustion-air vent inlet. — — 42

42. Check pressure tubing going to gas valve air pressure fitting for kinks. — — 43

43. Remove gas valve air pressure fitting and check gas valve for blockage. — — 44

44. Ensure vent and combustion-air pipes are not reversed. — — 45

45. Check burner orifice size and alignment. — — 46

46. Add restriction to combustion-air pipe or lengthen it a few feet if possible. — — 12

47. Jumper R and W2 thermostat terminals on furnace control board. — — 48

48. Do you have combustion oscillations in high fire? 41 12 —

Fault Code 41

BLOWER OUTSIDE VALID SPEED RANGE—This fault indicates 1 of the following:

• Blower motor speed cannot be maintained within 10% of calculated speed over a 30-sec period.

• Blower motor speed is less than 250 RPM or greater than 1300 RPM for more than 10 sec.

STEP ACTION YES NO GO TO

Turn power off, remove blower access panel, and disconnect R thermostat lead from furnace con-

trol board.

2. Turn power on and depress door switch. Use a piece of tape to hold switch closed. — — 3

3. Jumper R and W/W1 thermostat terminals on furnace control board. — — 4

4. Observe operation of furnace for next 8 minutes or until fault occurs. — — 5

5. Does Fault Code 44 flash twice followed by Fault Code 41? 6 7 —

After about 10 minutes of operation, furnace will lock out and flash Fault Code 12. Go to page num-

ber indicated in Index for Fault Code 12.

7. Does only Fault Code 41 flash? 11 8 —

8. Does a different fault occur? 925 —

9. Go to page number indicated in Index for fault code flashed. — — INDEX

10. Go to page number indicated in Index for CLEANUP AND STARTUP INSTRUCTIONS. — — INDEX

11. Does blower motor suddenly stop 10 sec before fault is signaled? 12 21 —

12. Turn power off and disconnect jumper wire across R and W/W1 thermostat terminals. — — 13

13. Put setup switch SW-4 labeled EMER. HEAT in ON position. — — 14

14.

15. Check connectors PL3, PL10, PL11, PL12, PL13, B1, and B2. — — 16

16. Does motor operate intermittently in response to connectors and wires being moved? 17 18 —

17. Fix problem. —— 10

18. Does blower motor suddenly stop? 19 20 —

→19.

20. Replace furnace control board. —— 10

21. Turn power off and disconnect jumper wire across R and W/W1 thermostat terminals. — — 22

22.

Turn power on and wait several sec, then jumper R and W/W1 thermostat terminals on furnace control board.

Replace entire blower motor or blower control module attached to the blower motor. If you replace the blower control module go to step 26. If problem still persists on an intermittent basis after replacing blower motor or blower control module, contact your distributor.

Check connectors PL3, PL10, and PL13 for possible intermittent connection of ORANGE and VIOLET wires.

—— 2

— — INDEX

—— 15

— — INDEX

—— 23

Page 28

23. Are ORANGE and VIOLET wires from PL3 and PL13 making good contact? 24 17 —

→24.

→25.

Replace entire blower motor or blower control module attached to the blower motor. If you replace the blower control module go to step 26.

Go to page number indicated in Index for CLEANUP AND STARTUP INSTRUCTIONS. If problem persists on an intermittent basis, replace entire blower motor or blower control module attached to the blower motor. If your replace the blower control module go to step 26. If problem still persists on an intermittent basis after replacing blower motor, contact your distributor.

—— 17

— — INDEX

Wait at least 5 minutes after disconnecting line voltage from equipment before opening blower motor to prevent electric shock which can cause personal injury or death.

→26. Remove tape from door switch and turn power off at main disconnect. — — 27 →27. Disconnect PL10 from blower assembly. — — 28 →28. Remove control box assembly from blower shelf and position out of the way. — — 29 →29. Remove blower assembly from furnace. — — 30

→30.

→31.

→32.

→33.

→34. Did the motor pass the resistance check? 35 37 — →35. Does blower wheel turn freely with blower control module removed? 36 37 —

→36.

→37.

Disconnect both multi-pin connectors from blower control module attached to the blower motor. Be sure to depress release latches on connectors or they may get damaged.

Remove two 1/4-in. hex head bolts from blower control module attached to blower motor. DO NOT REMOVE TORX HEAD SCREWS located next to 1/4-in. hex head bolts.

When blower control module is completely detached from blower motor, verify with standard ohmmeter that the resistance from each motor lead in motor plug to unpainted motor end plate is greater than 100k ohms. Then verify motor windings are not shorted or open by measuring resistance between each combination of pins in motor plug (there are three different combinations, pin 1-2, pin 2-3, and pin 1-3).Resis-tance should be approxi-mately equal across each combination of pins.

Replace blower control module. Inspect failed blower control module for water damage. If present, find source of water and fix. Check A-coil and/or humidifier.

Replace entire blower motor including blower control module. Inspect blower control module for water damage. If present, find source of water and fix. Check A-coil and/or humidifier.

——31

——32

——33

——34

——10

Page 29

Fault Code 42

INDUCER OUTSIDE VALID SPEED RANGE—This fault indicates that inducer motor is not operating at calculated RPM or has not started within 10 sec after a call for heat.

STEP ACTION YES NO GO TO

Turn power off, remove blower access panel, and disconnect all thermostat leads from furnace con-

trol board.

2. Turn power on and depress door switch. Use a piece of tape to hold switch closed. — — 3

3. Jumper R and W/W1 thermostat terminals on furnace control board. — — 4

4. Observe operation of furnace for next 8 minutes or until fault occurs. — — 5

5. Does fault occur again? 96 —

6. Does a different fault occur? 760 —

7. Go to page number indicated in Index for fault code flashed. — — INDEX

8. Go to page number indicated in Index for CLEANUP AND STARTUP INSTRUCTIONS. — — INDEX

9. Does fault occur within 11 sec after a call for heat? 52 35 —

10. Do you have 120v between I1 and I2 on furnace control board? 11 14 —

11. Do you have 120v between terminals PL7-6 and PL7-12? 13 12 —

12.

13. Are all pins and wire leads intact on connectors between furnace control board and inducer motor? 15 14 —

14. Fix problem. —— 8

15.

16. Put setup switch SW-4 for EMER. HEAT in ON position. — — 17

17. Jumper R and W/W1 thermostat terminals on furnace control board. — — 18

18. Does inducer motor turn on? 30 19 —

19. Does inducer wheel rub against inducer housing? 14 20 —

20. Turn power off. —— 21

21. Does inducer wheel turn freely? 24 22 —

22. Replace inducer motor or inducer motor assembly. — — 8

23. Replace furnace control board. —— 8

24.

25. Turn power on and wait a few sec for self test before proceeding to next step. — — 26

26.

27. Turn power off. —— 28

28. Do you have continuity between PL7-2 and PL1-6? 22 29 —

29. You have an open wire or bad terminal on BROWN wire between connectors PL7 and PL1. — — 14

30.

31.

32. Turn power off. —— 33

33. Do you have continuity between PL7-1 and PL1-5? 22 34 —

34. You have an open wire or bad terminal on ORANGE wire between connectors PL7 and PL1. — — 14

35.

36. Is inducer motor rotating in direction shown on inducer housing? 37 22 —

37. Turn power off and disconnect jumper wire across R and W/W1 thermostat terminals. — — 38

38.

39.

40.

41. Turn power off. —— 42

42. Is inducer blower wheel okay? 44 43 —

You have an open wire or bad terminal on either the BLACK or WHITE wire between furnace control board and inducer motor MTR1.

Turn power off and disconnect jumper wire across R and W/W1 thermostat terminals. Turn power on and wait a few sec for self test before proceeding to next step.

Disconnect jumper wire across R and W/W1 thermostat terminals and put setup switch SW-4 for EMER. HEAT in OFF position.

Check 12-vdc line. To do this, connect a DC voltmeter across terminals PL1-6 BROWN (+) and PL1-7 GREEN (-). Is voltage across BROWN and GREEN wires 11.5 — 12.5 vdc?

Disconnect jumper wire across R and W/W1 thermostat terminals and put setup switch SW-4 for EMER. HEAT in OFF position.

Check RPM feedback line. To do this, connect a DC voltmeter across terminals PL1-6 BROWN (+) and PL1-5 ORANGE (-), then put setup switch SW-6 for COMPONENT TEST in ON position. Does voltage across BROWN and ORANGE wires change between states as shown below?

• State 1—OFF (11.5 — 12.5 vdc)

• State 2—LOW (10.2 — 11.2 vdc)

• State 3—HIGH (8.4 — 9.4 vdc)

Does fault occur a few sec after low-pressure switch LPS makes?

NOTE: Check for 24v between the N.O. (Normally Open) contact on low-pressure switch LPS and Com on furnace control board to know when low-pressure switch LPS makes.

Connect 1 side of a slope manometer with a tee to collector box pressure tap. Connect other side with a tee to gas valve air pressure fitting. Refer to pressure check diagram in Appendix C.

Turn power on and wait several sec, then jumper R and W/W1 thermostat leads on furnace control board.

Do you have more than 1.0 in. wc pressure drop (0.80 in. wc on trophy unit) across heat exchangers when low-pressure switch LPS makes?

NOTE: Check for 24v between the N.O. (Normally Open) contact on low-pressure switch LPS and Com on furnace control board to know when low-pressure switch LPS makes.

—— 2

—— 14

—— 16

—— 25

27 23 —

—— 31

23 32 —

36 48 —

—— 39

—— 40

47 41 —

Page 30

43. If possible, replace inducer wheel. Otherwise, replace inducer motor assembly. — — 8

44. Is there any frost build-up on combustion-air inlet? 45 46 —

45.

→46.

→47. Replace pressure switch assembly. — — 70 →48. Is unit a trophy unit? 50 49 — →49. Does fault occur before blower motor turns ON? 47 51 —

→50.

→51. Replace furnace control board. —— 70

52. Turn power off and disconnect jumper wire across R and W/W1 thermostat terminals. — — 53

53. Turn power on and wait several sec before proceeding to next step. — — 54

54. Disconnect collector box tube to pressure switch assembly. — — 55

55. Jumper R and W/W1 thermostat terminals on furnace control board. — — 56

56. Does Fault Code 42 occur within 11 sec after a call for heat? 57 58 —

57. Reconnect collector box tube to pressure switch assembly. — — 10

58. Reconnect collector box tube to pressure switch assembly. — — 36

59.

60. Turn power off and disconnect jumper wire across R and W/W1 thermostat terminals. — — 61

61.

62.

63. Turn power off and disconnect jumper wire across R, W/W1, and W2 thermostat terminals. — — 64

64.

65.

66.

→67. Does fault occur a few sec after main burners ignite? 63 68 — →68. Observe operation of furnace in high heat for next 8 minutes or until fault occurs. — — 69 →69. Does the fault occur? 22 59 — →70. If problem still persists check for internal restriction in coupling box or secondary heat exchangers. — — 14

The problem is caused by reversed vent and combustion-air pipes or some other moist air entering combustion-air pipe.

You have inadequate combustion-air supply. This may be caused by:

- Excessive restriction in combustion-air or vent pipe.

- Internal restriction in coupling box or secondary heat exchangers

Replace pressure switch assembly with pressure switch assembly used in NON-trophy models or replace furnace control board. If you replace furnace control board make sure replacement control has a date code of 9837 or later. Only replace the pressure switch assembly or the furnace control board NOT both.

Go to page number indicated in Index for CLEANUP AND STARTUP INSTRUCTIONS. If problem persists on an intermittent basis, contact your distributor.

Turn power on and wait several sec, then jumper R, W/W1, and W2 thermostat terminals on furnace control board.

Does fault occur a few sec after high-pressure switch HPS makes?

NOTE: Check for 24v between the N.O. (Normally Open) contact on high-pressure switch HPS and Com on furnace control board to know when high-pressure switch HPS makes.

Connect 1 side of a slope manometer with a tee to collector box pressure tap. Connect other side with a tee to gas valve air pressure fitting. Refer to pressure check diagram in Appendix C.

Turn power on and wait several sec, then jumper R, W/W1, and W2 thermostat terminals on furnace control board.

Do you have more than 1.9 in. wc pressure drop across heat exchangers when high-pressure switch HPS makes?

NOTE: Check for 24v between the N.O. (Normally Open) contact on high-pressure switch HPS and Com on furnace control board to know when high-pressure switch HPS makes.

—— 14

—— 70

— — INDEX

—— 62

63 67 —

—— 65

—— 66

47 44 —

Fault Code 43

PRESSURE SWITCH CALIBRATION FAULT—Indicates low-pressure switch LPS and high-pressure switch HPS "make" points during high-heat purge are not within calibration range. This is determined by reading inducer motor RPM when low-pressure switch LPS and high-pressure switch HPS make. Then the following comparison is made:

0.55

If this relationship is not within range specified, furnace control board starts flashingfault colde43, shutsunit down (inducer runs for 15 sec), waits 2 minutes, stops flashing fault code, and restarts heating cycle.

→

It can also indicate that the high-pressure switch HPS made before the low-pressure switch LPS during either low-heat or high-heat purge.

STEP ACTION YES NO GO TO

Turn power off, remove blower access panel, and disconnect all thermostat leads from furnace con-

trol board.

2. Turn power on and depress door switch. Use a piece of tape to hold switch closed. — — 3

3. Jumper R, W/W1, and W2 thermostat terminals on furnace control board. — — 4

RPM (low)

‹

RPM (high)

‹ 0.90

—— 2

Page 31

4. Observe operation of furnace for several minutes or until fault occurs. — — 5

5. Does fault occur again? 96 —

6. Does a different fault occur? 78 —

7. Go to page number indicated in Index for fault code flashed. — — INDEX

8. Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS. — — INDEX

9. Is collector box and inducer housing properly draining condensate? 11 25 —

10. Fix problem. —— 8

11. Are pressure switches wired correctly? 13 10 —

12. Replace pressure switch assembly. — — 8

13.

14.

15.

16.

17. Replace furnace control board. —— 8

18. Turn power off. —— 19

19.

→20.

21.

22. Does a Fault Code 32 occur? 17 23 —

23. Reconnect BROWN wire to N.O. (Normally Open) contact on high-pressure switch HPS. — — 24

24.

25. The vent tube to drain trap, drain trap, or drain line is clogged. — — 10

Do you have 24v between C (Common) on low-pressure switch LPS and Com on furnace control board?

The YELLOW wire to low-pressure switch LPS is not making good connection. Repair wire or replace harness.

Turn power off and disconnect jumper wire across R, W/W1, and W2 thermostat terminals. Turn power on and wait a few sec for self test, then reconnect jumper across R, W/W1, and W2 thermostat terminals.

Do you have 24v between connector terminal PL2-2 and Com on furnace control board when fault occurs?

Do you have continuity across terminal PL2-2 and N.O. (Normally Open) contact on low-pressure switch LPS?

Turn power off and disconnect jumper wire across R, W/W1, and W2 thermostat terminals. Disconnect BROWN wire from N.O. (Normally Open) contact on high-pressure switch HPS. Turn power on and wait a few sec for self test, then reconnect jumper across R and W/W1 thermostat terminals.

The problem may be caused by a sag in vent pipe. If this is not the problem and fault still occurs, replace pressure switch assembly.

15 14 —

—— 8

—— 16

21 18 —

12 20 —

—— 10

—— 22

—— 8

Page 32

Fault Code 44

BLOWER CALIBRATION FAULT-This fault indicates that calculated blower motor speed isbelow 250or above 1300 RPM. When Fault Code 44 occurs in HEATING, COOLING, or CONTINUOUS FAN mode, unit operates as shown below. Keep in mind that whenever furnace control board shuts unit down in heating mode, gas shuts off immediately, inducer continues running for 15 sec, and blower runs at default (or previous) speed control signal for selected off delay.

• HEATING—During a call for heat, the desired low-heat and high-heat blower RPMs are calculated at the same time. If desired low-heat blower RPM is less than 250 or greater than 1300 RPM, furnace control board starts flashing Fault Code 44, shuts unit down, waits 2 minutes, stops flashing Fault Code 44, and restarts heating cycle. If this happens on 2 consecutive cycles, furnace control board locks out on Fault Code 12. During this sequence, it is possible for furnace control board to start flashing Fault Code 41 instead of Fault Code 44. This indicates that blower calibration failed and blower speed during off delay is out of range.

When unit is operating in low heat and furnace control board (date code 9505 or earlier) is flashing Fault Code 44, it indicates that desired high-heat blower RPM is greater than 1300 RPM, and unit remains running in low fire-mode for rest of heating cycle.

When unit is operating in high heat and furnace control board (date code 9506 or later) is flashing Fault Code 44, it indicates that desired high-heat blower RPM is greater than 1300 RPM, but furnace control board is running blower at default speed of 1200 RPM. Under this condition, the high-fire temperature rise could be outside rise range and can cause limit cycling to occur.

• COOLING—If desired cooling blower RPM is less than 250 or greater than 1300 RPM, furnace control board starts flashing Fault Code 44 and runs at default (or previous) cooling speed control signal for rest of cooling cycle. During this sequence, it is possible for furnace control board to start flashing Fault Code 41 instead of Fault Code 44. This indicates that blower calibration failed and blower speed for cooling is also out of range.

• CONTINUOUS FAN—If desired continuous fan blower RPM is less than 250 or greater than 1300 RPM, furnace control board will start flashing Fault Code 44 and run at default (or previous) continuous fan speed control signal for the rest of continuous fan cycle. During this sequence, it is possible for furnace control board to start flashing Fault Code 41 instead of Fault Code 44. When this happens, it indicates blower calibration failed and blower speed for continuous fan is also out of range.

STEP ACTION YES NO GO TO

Turn power off, wait 30 sec, then restore power. Reset thermostat. Observe operation of furnace

through 1 heating cycle.

NOTE: Blower access panel must be in place.

2. Does Fault Code 44 flash twice followed by Fault Code 41? 3 4 —

Eventually furnace will lock out on Fault Code 12 given enough time. Go to page number indicated

in Index for Fault Code 12.

4. Does only Fault Code 44 occur? 85 —

5. Does a different fault occur? 611 —

6. Go to page number indicated in Index for fault code flashed. — — INDEX

7. Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS. — — INDEX

8. Does unit operate in low fire while flashing Fault Code 44? 9 3 —

You have excessive restriction in air delivery system. Check filter(s) and ductwork. If problem still persists, replace furnace control board. Make sure replacement board has a date code of 9506 or

later. This new furnace control board will allow unit to run in high fire when necessary. See description of operation at start of Fault Code 44. If problem still persists, use Appendix E to evaluate.

10. Fix problem. —— 7

11.

12. Does Fault Code 44 occur? 13 14 —

13.

14.

15. Does unit operate in high fire while flashing Fault Code 44? 16 7 —

16.

Turn power off, wait 30 sec, then restore power. Reset thermostat. Observe operation of furnace through 1 cooling cycle.

NOTE: Blower access panel must be in place.

You have excessive restriction in air delivery system. Check filter(s) and ductwork. Furnace blower will operate in cooling mode at default speed. Check outdoor unit suction pressure and verify charge to determine if indoor airflow is sufficient. If not, refer to Appendix E to evaluate.

Turn power off, wait 30 sec, then restore power. Reset thermostat. Observe operation of furnace after it goes into high fire.

NOTE: Blower access panel must be in place.

You have excessive restriction in air delivery system. Check filter(s) and ductwork. Furnace blower will operate in high-fire speed at 1200 RPM. Check temperature rise of furnace and make sure unit does not trip primary limit. If it does, refer to Appendix E to evaluate.

—— 2

— — INDEX

—— 10

—— 12

—— 10

—— 15

—— 10

Page 33

CLEANUP AND START-UP INSTRUCTIONS

1. Start furnace using procedure outlined on Lighting Instructions attached to furnace. Observe operation of furnace through at least 1 complete heating cycle controlled from room thermostat. Observe each cycle for 20 minutes or until a fault code is flashed. If a fault occurs, refer to the Index.

2. Recycle as necessary and check thermostat heat anticipator setting, gas input rates, and temperature rises. These procedures are outlined in Installation, Start-Up, and Operating Instructions.

3. Check operation of safety devices: pressure switches, limit switch, and flame roll out switch.

4. Put setup switch SW-1 in ON position and jumper R, W/W1, and Y/Y2 terminals on furnace control board simultaneously to clear fault history.

5. Put setup switch SW-1 in OFF position.

6. Put all setup switches in their proper positions.

7. Remove tape from the door switch.

8. Replace thermostat leads (if necessary).

9. Set thermostat in AUTO position, calling for heat.

10. Set thermostat to desired temperature.

11. Replace bloweraccess panel and main furnace door. Clean up.

Page 34

Appendix A

Board Layout and Schematic

P/N HK42FZ003 P/N HK42FZ012

SURFACE IGNITOR

HOT

CONNECTOR

EAC-ELECTRONIC

AIR CLEANER

TERMINALS

(115-VAC 1 AMP MAX)

MAIN HARNESS

CONNECTOR

MAIN BLOWER

CONTROL WIRE

CONNECTOR

TRANSFORMER

24-V 

CONNECTORS

SEC-2 SEC-1

I2B2 L2P2



I1B1 L1P1

I2B2 L2P2

115-V CONNECTORS (SEE DETAILS ABOVE)

PRESSURE SWITCH CONNECTOR

HUM

W/W2 Y/Y2

24V

COM

HUM-HUMIDIFIER TERMINAL (24-VAC 0.5 AMP MAX)

24-V THERMOSTAT TERMINALS

DEHUMIDIFY ENABLE (DE) (WHEN PROVIDED)

DEHUMIDIFIER (DEHUM)  CONNECTOR

3-AMP FUSE STATUS AND DIAGNOSTIC

LED LIGHTS

CONTINUOUS

FAN (CF) SETUP

SWITCHES

COMMUNICATION

CONNECTOR

Control Center

AIR CONDITIONING (A/C) SETUP SWITCH

SETUP SWITCHES (SW) AND BLOWER OFF DELAY SETUP SWITCHES

MODEL PLUG  



A98351

Page 35

NOTE: If wiring schematic on unit is different from one shown below, use wiring schematic on unit.

115VAC

FU1

EAC-1 EAC-2

180

SEC.

BPH

FLT

(1-8)

CFM

1600

TON

213

OFF

800

CFM

213

OFF

PL12

GRN WHT

BLK

YEL

12543

SEC-2

TRAN

24VAC

SEC-1

NOTE #6

PL1-9

225

SEC.

OFF-DELAY

BLOWER

COMP. TEST EMER. HEAT

LOW HEAT

CFM

2000

TON

213

OFF

CFM

1000

TON

2-1/2

213

OFF

VIO

RED

ORN

3168

MTR2

PCB

NOTE #5

PL1-11

D.C. POWER

ALS

HUMR

FRS

(WHEN USED)

DEHUM

HUM

SEC.

OFF

654

32 1

PL5

PL6

PL6 3-CIRCUIT COMM. CONNECTOR

PL7 12-CIRCUIT INDUCER MTR CONNECTOR

PL9 2-CIRCUIT HSI CONNECTOR

PL10 9-CIRCUIT BLOWER ADAPTER CONNECTOR

PCB

PL13

YEL

BLU

A/C AIR CONDITIONING (ADJUSTABLE TONNAGE)

ALS AUXILIARY LIMIT SWTICH OVERTEMP - MANUAL RESET SPST-(N.C)

CF CONTINUOUS FAN (ADJUSTABLE CFM)

CPU1 MAIN MICROPROCESSOR & CIRCUITRY

CPU2 IGNITION MICROPROCESSOR & CIRCUITRY

LEGEND

HSI

OFF-DELAY

24VAC-3A

LEDS

A/C AND CF

SELECT. CHART

SWITCH

A/C AND CF

SELECT . CHAR T

SWITCH

RED ORN

VIO

YEL BLU

PL11

PL12

SELECTION CHART

123

234

CF A/C

123

(1-4)

1200

A/C CF

213

POS.

A/C CF

DEFAULT DEFAULT

213

POS.

PL4 PL9

HSIR

EAC

135

SEC.

OFF78OFF78OFF

123456

CFM

1400

TON

3-1/2

213

OFF

600

CFM

TON2TON

1-1/2

213

OFF

NOTE

IND.

PL11

MTR2

T 2

ILK

FU2

BLK

WHT

BLK

ILK

MTR1

060080

042080

060100

MTR1

412

T 1

GRN

12104 612

060120

GRN

ORN

BRN

PL2

WHT

GRN

PL13

12345 PL3

(WHEN USED)

LGPS

ORN

NOTE #11

Y/Y2

1234

HUM

WHT

BLK

RED BRN

10 11

RED

GRN

BRN

ORN

YEL

BLU

2 1

PL1

RED

NOTE #3

PL7

PCB

NOTE #5

D.C.

POWER

SUPPLY

SW - 4

EMER. HEAT

CPU2

PL1

BLU

TRAN HPS

WHT

BLK

RED

BLK

WHT

HSI

PL9

FSE

CPU1

NOTE #11

LPS

YEL

ORN

BLK

YEL

T 1

T 2

PL4

WHT

BLK

EAC2 EAC1

1.5 AMP

BRN

BLU

RED

654

RED

PL7

BLK

WHT GRN

YEL

BRN

ORN

FRS LS ALS

PL11

IND

NOTE # 7

PL11

12345

PL10

B1 7

BLOWER

RED

BRN

BLU

NOTE

FUSE

DEHUM

W/W1

FU1

SEC-1

SEC-2

WHT

PL3

5BLU 4YEL 3VIO 2ORN 1RED

BLK

RED ORN VIO YEL BLU WHT BLK

987654321

PL10

SCHEMATIC DIAGRAM

(NATURAL GA S & PR O P ANE )

EQUIPMENT GROUND

TO 115 VAC FIELD DISCONNECT

NOTE #2

(WHEN REQ'D)

FUSED DISCONNECT SWITCH

JUMPERS

1-4 2-5 3-6

SIZE

042040

042060

MODEL

HPS

PL1-7

NOTE #3

PL1-10

PL1-2

SUPPLY

EAC

GVR

CPU1

Y/Y2

W/W1

PL11 1-CIRCUIT INDUCTOR SPLICE CONNECTOR

PL12 5-CIRCUIT BLOWER POWER CONNECTOR

PL13 16-CIRCUIT BLOWER CTRL. CONNECTOR

SW1 MANUAL SWITCH, FAULT DISPLAY, SPST-(N.O.)

SW2 MANUAL SWITCH, LOW HEAT, SPST-(N.O.)

SW3 MANUAL SWITCH, BYPASS HUMIDIFIER, SPST-(N.O.)

JUMPER TO ENABLE DEHUM INPUT

DE DEHUMIDIFY ENABLE - IF DE CONNECTION PROVIDED REMOVE

DEHUM DEHUMIDIFICATION CONNECTION (24VAC .02 AMPS)

EAC-1 ELECTRONIC A IR CLEANER CONNECTION (115 VAC 1.5 AMP MAX.)

EAC-2 ELECTRONIC AIR CLEANER CONNECTION (COMMON)

FRS FLAME ROLLOUT SWITCH - MANUAL RESET, SPST-(N.C.)

PL2-4

LPS

NOTE # 11

LGPS

NOTE #11

PL2-2

HUMR

FSE

(WHEN USED)

PL2-1

PL1-1

CPU2

GVR

HSIR

NOTES:

1. If any of the original equipment wire is replaced use wire rated for 105˚C.

2. Use only copper wire between the disconnect switch and the furnace junction box (JB).

3. This wire must be connected to furnace sheet metal for control to prove flame.

4. Symbols are electrical representation only.

5. Solid lines, inside circuit board PCB are printed circuit board traces and are not depicted as shown in the legend.

6. Replace only with a 3 AMP fuse.

7. Inductor used on all 060 or -20 airflow units.

8. Blower-on delay, gas heating 60 seconds low heat, 35 seconds high heat, cooling or heat pump 2 seconds ..

9. Blower-off delay, gas heating 90, 135, 180 or 225 seconds, cooling or heat pump 90 seconds.

10. Ignition-lockout will o cc ur af te r fou r consecutive unsu c ces sful trials-for-ignition . Co n tro l will a uto -re set afte r thre e h ours.

11. Factory connec ted when LG PS not used.

A98305

322296-101 R EV . C

Wiring Schematic

JUNCTION

UNMARKED TERMINAL

PCB TERMINAL (FACTORY CONNECTED)

FACTORY WIRING (115 VAC)

FACTORY WIRING (24 VAC)

FIELD WIRING (115 VAC)

CONDUCTOR ON PCB

FIELD WIRING SCREW TERMINAL

TERMINAL BLOCK - MARKED TERMINAL

FIELD GROUND

EQUIPMENT GROUND

FIELD SPLICE

PCB TERMINAL (FIELD CONNECTION)

PLUG RECEPTACLE

SW4 MANUAL SWITCH, EMERGENCY HEAT, SPST-(N.O.)

SW5 MANUAL SWITCH, M ULTIPLE ZONE, SPST-(N.O.)

SW6 COMPONENT TEST, SPST-(N.O.)

SW7-8 MANUAL SWITCH, BLOWER OFF-DELAY, SPST-(N.O.)

TRAN TRANSFOR M ER - 115VAC/24VAC

(FIELD INSTALLED & SUPPLIED)

FSE FLAME PROVING SENSOR ELECTRODE

FU1 FUSE, 3 AMP, AUTOMOTIVE BLADE TYPE, FACTORY INSTALLED

FU2 FUSE OR CIRCUIT BREAKER CURRENT INTERRUPT DEVICE

GV GAS VALVE

GVR GAS VALVE RELAY, DPST-(N.O.)

HI GAS VALVE HIGH STAGE OPERATOR

HPS HIGH HEAT PRESSURE SWITCH, SPST-(N.O.)

HSI HOT SURFACE IGNITOR (115 VAC )

HSIR HOT SURFACE IGNITOR RELAY, SPST-(N.O.)

HUM 24VAC HUMIDIFIER CONNECTION (.5 AMP. MAX.)

HUMR HUMIDIFIER RELAY, SPST-(N.O.)

ILK BLOWER ACCESS PANEL INTERLOCK SWITCH, SPST-(N.O.)

IND INDUCTOR (NOTE #7)

JB JUNCTION BOX

LEDS LIGHT EMITTING DIOES FOR STATUS CODES

LGPS LOW GAS PRESSURE SWITCH, SPST (N.O.)

LPS LOW HEAT PRESSSURE SWITCH, SPST-(N.O.)

LS LIMIT SWITCH, AUTO RESET, (N.C.)

MTR1 MOTOR (I CM ) INDU C E R

MTR2 MOTOR (I CM ) BLO WE R

PCB PRINTED CIRCUIT BOARD

PL1 11-CIRCUIT CONNECTOR

PL2 4-CIRCUIT PRESSURE SWITCH CONNECTOR

PL3 5-CIRCUIT BLOWER MTR CONNECTOR

PL4 2-CIRCUIT HSI CONNECTOR

PL5 6-CIRCUIT MODEL PLUG

Page 36

THERMOSTAT

1

FIELD-SUPPLIED

24-VAC SPST RELAYS

Fig. 5—Isolation of W/W1 and Y/Y2

Thermostat Circuits

FURNACE CONTROL

BOARD

Appendix B

Isolation Circuits

OUTDOOR

Com

UNIT

A95097

–FIELD-SUPPLIED

1

24-VAC SPST RELAY



FIELD-SUPPLIED

24-VAC (40VA)

TRANSFORMER

120VAC

Y G C

THERMOSTAT FURNACE

G Com

CONTROL

OUTDOOR

UNIT

BOARD

A95098

Fig. 6—Isolation of Outdoor Unit with a Separate

24-v Supply

Appendix C

Pressure Check Diagram

0-4 IN.

SLOPE GAGE

A95050

UNIT SIZE (BTUH)

HIGH-PRESSURE SWITCH LOW-PRESSURE SWITCH

Make Point Break Point Make Point Break Point

40,000 1.81 in. wc max 1.63 in. wc ± 0.05 0.75 in. wc max 0.60 in. wc ± 0.05 60,000

80,000

100,000

1.81 in. wc max 1.63 in. wc ± 0.05 0.95 in. wc max 0.80 in. wc ± 0.05

120,000

Page 37

Appendix D

Quick Motor Test Procedure

In an effort to provide a method of troubleshooting inducer and blower motor by themselves, the following procedure may save you some time in the event any of the following fault codes are the reason for service call (12, 32, 41, 42, or 44). If you get any other fault code, you should use main troubleshooting guide to isolate problem.

STEP ACTION YES NO GO TO

1. Turn power off, remove blower access panel, and disconnect R thermostat lead. — — 2

2. Turn power on and depress door switch. Use a piece of tape to hold switch closed. — — 3

3. Put setup switch SW-6 for COMPONENT TEST in ON position. — — 4

4. After COMPONENT TEST is completed, does Fault Code 11 flash? 5 8 —

Turn power off, put setup switch SW-6 for COMPONENT TEST in OFF position, and reconnect R

thermostat lead to furnace control board. Replace blower access panel and turn power on. Wait a few sec, then reset thermostat. Observe

operation of furnace through 1 heating cycle.

7. Go to page number indicated in Index for START HERE section. — — INDEX

8. Does Fault Code 42 flash? 927 —

9. Does inducer motor MTR1 turn on and come up to speed? 24 10 —

10. Does inducer wheel rub against inducer housing? 16 11 —

11. Does inducer wheel turn freely? 12 19 —

12. Do you have 120v between I1 and I2 on furnace control board? 13 16 —

13. Do you have 120v between terminals PL7-6 and PL7-12? 15 14 —

14.

15. Are all pins and wire leads intact on connectors between furnace control board and inducer motor? 18 16 —

16. Fix problem. —— 17

17. Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS. — — INDEX

18.

19.

20.

21.

22. Replace furnace control board. —— 17

23.

24.

25.

26.

27. Does Fault Code 41 flash? 28 7 —

28. Does blower motor MTR2 turn on and come up to speed? 48 29 —

29. Remove tape from door switch and turn power off at main disconnect. — — 30

You have an open wire or bad terminal on either the BLACK or WHITE wire between furnace control board and inducer motor MTR1.

Check Inducer PW line. To do this, connect a DC voltmeter across terminals PL7-2 BROWN (+) and PL7-10 YELLOW (-) on inducer motor. Repeat COMPONENT TEST by turning setup switch SW-6 OFF and then back ON. Does voltage across PL7-2 and PL7-10 change between states as shown below?

• State 1—OFF (-0.1 — 0.1 vdc)

• State 2—LOW (2.0 — 3.0 vdc)

• State 3—HIGH (7.0 — 8.0 vdc)

Replace inducer motor or inducer motor assembly. Inspect electronics portion of failed motor for water damage. If present, find source of water and fix. Check A-coil and/or humidifier.

Disconnect PL7 from inducer motor and connect a DC voltmeter across terminals PL7-2 BROWN (+) and PL7-10 YELLOW (-). Repeat COMPONENT TEST by turning setup switch SW-6 OFF and then back ON. Does voltage across PL7-2 and PL7-10 change between states as shown below?

• State 1—OFF (-0.1 — 0.1 vdc)

• State 2—LOW (6.0 — 7.0 vdc)

• State 3—HIGH (10.5 — 11.5 vdc)

Connect a DC voltmeter across terminals PL1-6 BROWN (+) and PL1-4 YELLOW (-) on furnace control board. Repeat COMPONENT TEST by turning setup switch SW-6 OFF and then back ON. Does voltage across PL1-6 and PL1-4 change between states as shown below?

• State 1—OFF (-0.1 — 0.1 vdc)

• State 2—LOW (6.0 — 7.0 vdc)

• State 3—HIGH (10.5 — 11.5 vdc)

You have an open wire or bad terminal on either the BROWN or YELLOW wire between connectors PL1 and PL7. Repair it or replace main harness.

Check RPM feedback line. To do this, connect a DC voltmeter across terminals PL7-2 BROWN (+) and PL7-1 ORANGE (-) on inducer motor. Repeat COMPONENT TEST by turning setup switch SW-6 OFF and then back ON. Does voltage across BROWN and ORANGE wires change between states as shown below?

• State 1—OFF (11.5 — 12.5 vdc)

• State 2—LOW (10.2 — 11.2 vdc)

• State 3—HIGH (8.4 — 9.4 vdc)

Connect a DC voltmeter across terminals PL1-6 BROWN (+) and PL1-5 ORANGE (-) on furnace control board. Repeat COMPONENT TEST by turning setup switch SW-6 OFF and then back ON. Does voltage across BROWN and ORANGE wires change between states as shown below?

• State 1—OFF (11.5 — 12.5 vdc)

• State 2—LOW (10.2 — 11.2 vdc)

• State 3—HIGH (8.4 — 9.4 vdc)

You have an open wire or bad terminal on ORANGE wire between connectors PL1 and PL7. Repair it or replace main harness.

—— 6

—— 7

—— 16

19 20 —

—— 17

19 21 —

23 22 —

—— 17

25 19 —

22 26 —

—— 17

Page 38

30. Does blower wheel rub against blower housing? 16 31 —

31. Does blower wheel turn freely? 32 33 —

32. Is blower wheel firmly mounted on motor shaft? 34 16 —

→33.

34. Put setup switch SW-6 for COMPONENT TEST in OFF position. — — 35

35.

36. Do you have 120v between B1 and B2 on furnace control board? 37 16 —

37. Do you have 120v between BLACK and WHITE power leads at blower motor MTR2? 39 38 —

38.

39.

40.

41.

42.

43. Put setup switch SW-6 for COMPONENT TEST in OFF position. — — 44

44.

45.

46.

47.

48.

49.

50.

Replace blower motor or blower control module attached to the blower motor. If you replace the blower control module go to step 51. Always inspect failed motor for water damage. If present, find source of water and fix. Check A-coil and/or humidifier.

Turn power on and depress door switch. Use a piece of tape to hold switch closed. Wait a few sec for self test before proceeding to next step.

You have an open wire or bad terminal on either the BLACK or WHITE wire between furnace control board and blower motor MTR2. Repair it or replace blower harness(es).

Check Blower ON/OFF line. To do this, connect a DC voltmeter across terminals PL3-1 RED (+) and PL3-5 BLUE (-), then put setup switch SW-6 for COMPONENT TEST in ON position. Does voltage across RED and BLUE wires change between states as shown below?

• State 1—OFF (-0.1 — 0.1 vdc)

• State 2—ON (9.0 — 10.0 vdc)

Disconnect PL3 from furnace control board and connect a DC voltmeter across terminals PL3-1 (+) and PL3-5 (-) on furnace control board. Repeat COMPONENT TEST by turning setup switch SW-6 OFF and then back ON. Does voltage across PL3-1 and PL3-5 change between states as shown below?

• State 1—OFF (-0.1 — 0.1 vdc)

• State 2—ON (11.0 — 12.0 vdc)

You have an open wire or bad terminal on either the RED or BLUE wire between connectors PL13 and PL3. Repair it or replace blower harness(es).

Connect a DC voltmeter across RED (+) and BLUE (-) wires at connector PL13. Repeat COMPONENT TEST by turning setup switch SW-6 OFF and then back ON. Does voltage across RED and BLUE wires change between states as shown below?

• State 1—OFF (-0.1 — 0.1 vdc)

• State 2—ON (9.0 — 10.0 vdc)

Check Blower PW line. To do this, connect a DC voltmeter across terminals PL3-1 RED (+) and PL3-4 YELLOW (-) on furnace control board, then put setup switch SW-6 for COMPONENT TEST in ON position. Does voltage across RED and YELLOW wires change between states as shown below?

• State 1—OFF (-0.1 — 0.1 vdc)

• State 2—LOW (2.5 — 3.0 vdc)

• State 3—HIGH (7.0 — 7.5 vdc)

Disconnect PL3 from furnace control board and connect a DC voltmeter across terminals PL3-1 (+) and PL3-4 (-) on furnace control board. Repeat COMPONENT TEST by turning setup switch SW-6 OFF and then back ON. Does voltage across PL3-1 and PL3-4 change between states as shown below?

• State 1—OFF (-0.1 — 0.1 vdc)

• State 2—LOW (3.0 — 4.0 vdc)

• State 3—HIGH (9.0 — 10.0 vdc)

Connect a DC voltmeter across RED (+) and YELLOW (-) wires at connector PL13. Repeat COMPONENT TEST by turning setup switch SW-6 OFF and then back ON. Does voltage across RED and YELLOW wires change between states as shown below?

• State 1—OFF (-0.1 — 0.1 vdc)

• State 2—LOW (2.5 — 3.0 vdc)

• State 3—HIGH (7.0 — 7.5 vdc)

You have an open wire or bad terminal on either the RED or YELLOW wire between connectors PL13 and PL3. Repair it or replace blower harness(es).

Check RPM feedback line. To do this, connect a DC voltmeter across terminals PL3-2 ORANGE (+) and PL3-3 VIOLET (-). Repeat COMPONENT TEST by turning setup switch SW-6 OFF and then back ON. Does voltage across ORANGE and VIOLET wires change between states as shown below?

• State 1—OFF (12.0 — 12.5 vdc)

• State 2—LOW (10.7 — 11.7 vdc)

• State 3—HIGH (9.7 — 10.7 vdc)

Connect a DC voltmeter across ORANGE (+) and VIOLET (-) wires at connector PL13. Repeat COMPONENT TEST by turning setup switch SW-6 OFF and then back ON. Does voltage across ORANGE and VIOLET wires change between states as shown below?

• State 1—OFF (12.0 — 12.5 vdc)

• State 2—LOW (10.7 — 11.7 vdc)

• State 3—HIGH (9.7 — 10.7 vdc)

You have an open wire or bad terminal on either the ORANGE or VIOLET wire between connectors PL13 and PL3. Repair it or replace blower harness(es).

—— 16

—— 36

—— 17

42 40 —

33 22 —

—— 17

43 41 —

46 45 —

33 22 —

33 47 —

—— 17

22 49 —

50 33 —

—— 17

Page 39

Wait at least 5 minutes after disconnecting line voltage from equipment before opening blower motor to prevent electric shock which can cause personal injury or death.

→51. Remove tape from door switch and turn power off at main disconnect. — — 52 →52. Disconnect PL10 from blower assembly. — — 53 →53. Remove control box assembly from blower shelf and position out of the way. — — 54

→54.

→55.

→56.

→57.

→58.

→59. Did the motor pass the resistance check? 60 62 — →60. Does blower wheel turn freely with blower control module removed? 61 62 —

→61.

→62.

Remove blower assembly from furnace.

Disconnect both multi-pin connectors from blower control module attached to the blower motor. Be sure to depress release latches on connectors or they may get damaged.

Remove two 1/4-in. hex head bolts from blower control module attached to blower motor. DO NOT REMOVE TORX HEAD SCREWS located next to 1/4-in. hex head bolts.

Replace blower control module. Inspect failed blower control module for water damage. If present, find source of water and fix. Check A-coil and/or humidifier.

Replace entire blower motor including blower control module. Inspect blower control module for water damage. If present, find source of water and fix. Check A-coil and/or humidifier.

——55

——56

——57

——58

——59

——17

Page 40

Appendix E

Variable-Speed Condensing Furnace Duct Static and Blower

Operation

This variable-speed furnace has an Integrated Control and Motor called an ICM. This ICM is controlled as stated in Sequence of Operation section. This furnace does a good job compensating for an improperly sized duct system, but this ICM is not a fix for all bad ductwork.

This troubleshooting guide has shown that the blower does a calibration 20 sec at start of any operation of ICM. Note that blower calibration sequence is different when setup switch SW-5 is turned ON for multi-zone operation. (See Sequence of Operation section.) These blower calibrations help to ensure proper airflow in heating and cooling. In heating mode, this calibration helps ensure proper temperature rise which prolongs life of heat exchanger. In cooling mode, this calibration helps ensure proper CFM per ton of cooling.

If furnace is on a call for heat or cooling and duct static is too high, ICM tries to overcome external static pressure. If duct static is excessive, ICM RPM will be out of range and a Fault Code 44 will flash on circuit board. The ICM RPM range is 250 to 1300 RPM as stated in Fault Code 44 troubleshooting section. To check for excessive static pressure, use the following Air Delivery Curves and Duct Static Check Sheet later in this Appendix.

EXAMPLE: Furnace is a 100,000 Btuh input with a 5 ton blower cooling capacity. We measured total external static pressure (ESP) to be 0.4 in. wc in low-heat operation.

EXAMPLE AIR DELIVERY CURVE — 060100

HIGH

0.8 Constant System

0.7

0.6

0.5

0.4

0.3

LOW HEAT

Curves

HEAT

0.2

External Static Pressure (in. wc)

0.1

2 Ton

700 900

3 Ton

⁄2 Ton

1100 1300 1500

⁄2 Ton

CFM

4 Ton 5 Ton

1700 1900 2100

A98451

Use the dashed lines as guide lines. As you can see, the 0.4 in. wc total ESP is in the shaded area. The unit can deliver low heat, but as you follow the dashed guide lines, you seethat they do not cross the high-heat line untilit is off the chart, somewhere above 1.0 in. wc. The furnaces are rated at 0.5 in. wc total ESP and are tested to 0.8 in. wc total ESP.

See Static Pressure Reading Location Diagrams later in this Appendix for proper static reading locations. When checking total ESP, you must have blower operation without a Fault Code 44 occurring. If you have a Fault Code 44 in cooling and your setting is at 5 tons, set A/C tonnage to 4 tons and see if the Fault Code 44 goes away. If it does not, set switches to 3 tons, and so on until the Fault Code 44 goes away.

NOTE: When adjusting airflow, you must either turn power off or terminate thermostat call after every airflow adjustment. Record all static readings on Duct Static Check Sheet.

Solutions:

1. Dirty filter.

2. Plugged evaporator coil.

3. Re-size ductwork and/or layout.

SPECIAL NOTE: In zoningapplications, it is recommended that when zone controlsare applied,duct system be designed for sum of thepeaks plus 25% oversize to allow furnace to operate within its design parameters. Contact your distributor for further details.

Page 41

Air Delivery Curves

Air Delivery Curve — 040-14

0.8 Constant System

0.7

0.6

0.5

0.4

0.3

0.2

External Static Pressure (in. wc)

0.1

Curves

HIGH HEAT

LOW HEAT

11⁄2 Ton

500 600 700 800 900 1000

2 Ton 3 Ton

Air Delivery Curve — 080-14

0.8

0.7

0.6 Constant System

0.5

0.4

0.3

0.2

External Static Pressure (in. wc)

0.1

Curves

LOW HEAT

11⁄2 Ton

500 600 700 800 900 1000 1100

2 Ton 3 Ton 31⁄2 Ton21⁄2 Ton

⁄2 Ton

1100 1200 1300 1400 1500

CFM

HIGH HEAT

1200 1300 1400 1500

CFM

⁄

2

Ton

A93074

A97320

Air Delivery Curve — 060-14

HIGH

0.8

0.7

Constant System

Curves

HEAT

0.6

0.5 LOW

0.4

HEAT

0.3

0.2

External Static Pressure (in. wc)

0.1

11⁄2 Ton

2 Ton 3 Ton

⁄2 Ton

500 600 700 800 900 1000 1100 1200 1300 1400 1500

CFM

Air Delivery Curve — 080-20

HIGH

3 Ton

HEAT

⁄2 Ton

CFM

4 Ton 5 Ton

1600 1800 2000

0.8

Constant System

0.7

0.6

0.5

0.4

0.3

0.2

External Static Pressure (in. wc)

0.1

Curves

LOW HEAT

2 Ton

600 800

⁄2 Ton

1000 1200 1400

⁄

Ton

A97319

A97321

Air Delivery Curve—100-20

0.8 Constant System

0.7

0.6

0.5

0.4

0.3

0.2

External Static Pressure (in. wc)

0.1

Curves

LOW HEAT

2 Ton

700 900

21⁄2 Ton

1100 1300 1500

3 Ton

HIGH HEAT

CFM

31⁄2 Ton

4 Ton 5 Ton

1700 1900 2100

A97322

Air Delivery Curve—120-20

0.8

0.7

0.6

0.5

0.4

0.3

0.2

External Static Pressure (in. wc)

0.1

2 Ton

700 900

Constant System

21⁄2 Ton

Curves

LOW HEAT

3 Ton

1100 1300 1500

CFM

31⁄2 Ton

HIGH HEAT

4 Ton 5 Ton

1700 1900 2100

A97323

Page 42

Static Pressure Reading Location Diagrams

COMBUSTION AIR PIPE

VENT PIPE

OUTDOOR UNIT

RETURN STATIC

INCLINE MANOMETER

AIRFLOW

A/C COIL

HUMIDIFIER

GAS-FIRED ELECTRONIC AIR CLEANER

WATER HEATER

Basement — Upflow Application

Upflow Total Static Pressure Reading Locations

SUPPLY STATIC

INCLINE MANOMETER

A95090

HUMIDIFIER

SUPPLY STATIC

INCLINE MANOMETER

ELECTRONIC

AIR CLEANER

VENT

A/C COIL

AIRFLOW

Closet — Downflow Application

Downflow Total Static Pressure Reading Locations

RETURN STATIC

INCLINE MANOMETER

COMBUSTION AIR

OUTDOOR UNIT

A95091

Page 43

RETURN STATIC

COMBUSTION–AIR PIPE

COIL

INCLINE MANOMETER

ELECTRONIC

AIR CLEANER

AIRFLOW

VENT PIPE

FURNACE

CONDENSATE

DRAIN

AIR CONDITIONING

REFRIGERATION

PIPING

Attic — Horizontal Application

Horizontal Right and Left Airflow Total Static Pressure Reading Locations

SUPPLY STATIC

INCLINE MANOMETER

A95092

Example 1

Return ESP after filter 0.40 in. wc Supply ESP before coil 0.55 in. wc Total ESP 0.95 in. wc

Tools Needed:

1) Pitot Tube

1) Incline Manometer/Magnahelic

Both examples are correct. Example 1 ESP readings were taken as laid out in Static Pressure Reading Location Diagrams. Example 2 readings are taken as described. The coil and filter static pressure drops were taken from the manufacturer’s Product Data Sheets with the assumption that we are trying to deliver 2000 CFM (this will vary).

NOTE: By plotting total ESP of 0.95 in. wc on the air delivery curve of a 100,000 Btuh input furnace, a Fault Code 44 would flash. (See Example Air Delivery Curve.)

Example 2

Return ESP before filter 0.15 in. wc Filter Static Drop @ 2000 CFM 0.25 in. wc Supply ESP after coil 0.30 in. wc Coil Static Drop Wet 0.25 in. wc Total ESP 0.95 in. wc

Page 44

Duct Static Check Sheet

Furnace: Model Number Serial Number Position? U/F D/F H/R H/L

Outdoor Unit: Model Number Serial Number

What type of media filter is being used? What is static pressure drop across filter? At what CFM? Does fault code go away when you remove filter? What Zone System is applied? What Zone has highest total ESP? Is a Zone Bypass Damper being used? and is it operating (opening) What type of Bypass Humidifier is being used? Is Bypass Humidifier setup switch on or off?

If you have a Fault Code 41 and/or 44, do the following:

1. Turn power off to furnace and outdoor unit.

2. Set A/C setup switch for 2 tons (800 CFM).

3. Turn only power to furnace back on.

4. Set thermostat for a call for cooling.

5. Check supply and return ESP as in Appendix E. Add these 2 ESP readings together for Total ESP. Repeat these steps until a fault code flashes on the microprocessor. Log your information on this sheet.

• At Low Heat: Supply ESP Return ESP (Before or After Filter) Any Fault Code Flashing? If so what number?

• At High Heat: Supply ESP Return ESP (Before or After Filter) Any Fault Code Flashing? If so what number?

• At 2 Ton A/C Setting: Supply ESP Return ESP (Before or After Filter) Any Fault Code Flashing? If so what number?

• At 2.5 Ton A/C Setting: Supply ESP Return ESP (Before or After Filter) Any Fault Code Flashing? If so what number?

• At 3 Ton A/C Setting: Supply ESP Return ESP (Before or After Filter) Any Fault Code Flashing? If so what number?

• At 3.5 Ton A/C Setting: Supply ESP Return ESP (Before or After Filter) Any Fault Code Flashing? If so what number?

• At 4 Ton A/C Setting: Supply ESP Return ESP (Before or After Filter) Any Fault Code Flashing? If so what number?

• At 5 Ton A/C Setting: Supply ESP Return ESP (Before or After Filter) Any Fault Code Flashing? If so what number?

(Before or After Evaporator Coil)

Indoor Coil: Model Number Serial Number

Thermostat Electronic Air Cleaner

Page 45

Appendix F

Quick Reference Information

PRESSURE SWITCH MAKE/BREAK POINTS

UNIT SIZE (BTUH)

40,000 1.81 in. wc max 1.63 in. wc ± 0.05 0.75 in. wc max 0.60 in. wc ± 0.05 60,000

80,000 100,000 120,000

• Microamp Range: 0.5 to 6.0 microamps

• Typical Reading: 4 to 6 microamps

• Ohm reading of HSI unused: 45 to 90 ohms (resistance will go up over time)

• M to C: 98 ohms (solenoid coil)

• Hi to C: 1.5 ohm Bridge Rectifier (Use diode test function setting on ohm meter.)

• When you put unit into component test function, measure motor amp draw before power choke. Then repeat component test, but this time measure amp draw without power choke in line. The amp draw should be higher without power choke. Some ammeters will register a lower amp draw (look for a change in amperage).

1.81 in. wc max 1.63 in. wc ± 0.05 0.95 in. wc max 0.80 in. wc ± 0.05

HIGH-PRESSURE SWITCH LOW-PRESSURE SWITCH

Make Point Break Point Make Point Break Point

FLAME SENSOR MICORAMPERAGE

HOT SURFACE IGNITOR OHM READING

GAS VALVE OHM READINGS

POWER CHOKE

SPECIAL NOTE: ALL VOLTMETERS ARE NOT THE SAME, YOUR VOLTAGE READINGS WILL VARY. THIS APPLIES TO THE ENTIRE CONTENT OF THIS TROUBLESHOOTING MANUAL.

Page 46

Appendix G

Thermostat Staging Algorithm

• Unit Default: Algorithm is initiated with Low Heat for 16 minutes. If call for heat still exists, unit transfers into High Heat until thermostat is satisfied.

• Low Heat run time is calculated based on previous heating cycle.

• High Heat on time is not calculated. High Heat is energized 1 of 3 ways and runs until thermostat has been satisfied.

1. After Low Heat has run for 16 minutes and call for heat is still present.

2. When algorithm does its calculation of previous cycle and determines High Heat is necessary.

3. After the amount of calculated Low Heat on time has elapsed and there is still a call for heat present.

• The following flowchart shows how the algorithm calculates low heat on times. To use calculations, the amount of time unit ran in Low Heat (LH) and High Heat (HH) during previous cycle must be known. The algorithm uses these values to decide which stage of heat should be initiated on next call for heat.

• Four examples also follow illustrating what the unit will do on a cold start, coming out of night setback, coming on in low fire, and coming on in high fire.

EXAMPLE 1: Furnace ran for 16 minutes in Low Heat and 5 minutes in High Heat. LH=16 HH=5 Calculate: (228 X 16) + (350 X 5) = 5398

‹ 5398 ‹ 5600 ⇒ therefore calculate next cycle Low Heat run time.

3648 LH

run time

Heat if a call for heat is still present.

5600 − 5398

122

= 1.6 ⇒ therefore during next cycle, unit will run for 2 minutes in Low Heat and then switch to High

EXAMPLE 2: Furnace ran for 16 minutes in Low Heat and 10 minutes in High Heat. LH=16 HH=10 Calculate: (228 X 16) + (350 X 10) = 7148

7148

› 5600 ⇒ therefore next cycle will be initiated in High Heat. Low Heat run time is 0 minutes.

EXAMPLE 3: Furnace ran for 13 minutes in Low Heat (LH) and 5 minutes in High Heat (HH). This will happen if control algorithm calculated maximum Low Heat run time be 13 minutes based on a previous cycle. LH=13 HH=5 Calculate: (228 X 13) + (350 X 5) = 4714

3648

‹ 4714 ‹ 5600 ⇒ therefore calculate the next cycle Low Heat run time.

run time

heat is still present.

EXAMPLE 4: Furnace ran for 0 minutes in Low Heat and 10 minutes in High Heat. LH=0 HH=10 Calculate: (228 X 0) + (350 X 10) = 3500

3500 for heat is still present.

5600 − 4714

122

= 7.26 ⇒ therefore unit will run for 7 minutes in Low Heat and then switch to High Heat if a call for

‹ 3648 ⇒ therefore next cycle will be initiated in Low Heat up to 16 minutes maximum, then switch to High Heat if a call

Page 47

A95094

in High Heat until the

the call for heat still exists.

Low Heat for a maximum of 16

Unit will initiate the next cycle in

min. before initiating High Heat if

thermostat is satisfied.

Unit will initiate the next cycle

for heat?

Is there a call

The next cycle will be initiated

a call for heat is still present.

with the calculated Low fire run

time before initiating high heat if

as calculated.

The Low Heat and High Heat

run times for this cycle will be

Thermostat is satisfied.

by the following:

time will be 16 minutes.

Calculate Low Heat (LH) on

Yes

time will be 0 minutes.

Calculate Low Heat (LH) on

Yes

Unit will iniate the next cycle in

Low Heat to the nearest minute

run time

LH = (5600 - HL)/122

for a period of time as calculated

Yes

VARIABLE SPEED CONDENSING FURNACE ALGORITHM

using:

and High Heat (HH) values,

calculate the Heat Load (HL)

Using recorded Low Heat (LH)

HL=(228 X LH) + (350 X HH)

Is HL < 3648?

Is HL > 5600?

Is 5600 > HL > 3648?

FEBRUARY 1995

Page 48

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

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

Book 1 4 Tab 6a 8a

PC 101 Catalog No. 535-754 Printed in U.S.A. Form 58MVP-8SM Pg 48 9-99 Replaces: 58MVP-6SM

Carrier 58MVP User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual