Carrier 58MVP User Manual

58MVP Variable-Speed 2-Stage Electronic Condensing Furnace

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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 11ÐNo Fault in Recent History Display ................	13
Fault Code 12ÐBlower Calibration Lockout........................	13-15
Fault Code 13ÐLimit Switch Lockout..................................	15-16
Fault Code 14ÐIgnition Lockout................................................	17
Fault Code 21ÐInvalid Model Selection....................................	17
Fault Code 22ÐSet Up Error......................................................	18
Fault Code 23ÐInvalid Blower Airflow Selection ....................	18
Fault Code 24ÐSecondary Voltage Fuse Is Open................	19-20
Fault Code 31ÐHigh-Pressure Switch Fault.........................	21-22
Fault Code 32ÐLow-Pressure Switch Fault .........................	23-24
Fault Code 33ÐLimit Switch Fault.......................................	24-25
Fault Code 34ÐIgnition Proving Fault .................................	26-27
Fault Code 41ÐBlower Outside Valid Speed Range ...........	27-28
Fault Code 42ÐInducer Outside Valid Speed Range...........	29-30
Fault Code 43ÐPressure Switch Calibration Fault...............	30-31
Fault Code 44ÐBlower Calibration Fault ..................................	32
Cleanup and Start-Up Instructions ..............................................	33
APPENDIX AÐBoard Layout & Wiring Schematic ...........	34-35
APPENDIX BÐIsolation Circuits ..............................................	36
APPENDIX CÐPressure Check Diagram ..................................	36
APPENDIX DÐQuick Motor Test Procedure ......................	37-39
APPENDIX EÐVariable-Speed Condensing Furnace Duct Static
and Blower Operation.............................................................	40-44
APPENDIX FÐQuick Reference Information ...........................	45
APPENDIX GÐThermostat Staging Algorithm ...................	46-47

INSTRUCTIONS

This guide uses your expertise and observations to lead you to the 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 control board, you can 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	PC 101	Catalog No. 535-754	Printed in U.S.A.	Form 58MVP-8SM	Pg 1	9-99	Replaces: 58MVP-6SM
Tab	6a	8a

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.	Ð	Ð	2
	2.	Step 2 asks the question, "Are any LEDs flashing?". If low-pressure switch was defective, a low-	5	3	Ð
		pressure switch fault code would be flashing, so the answer is "YES." We go to Step 5.
	5.	Step 5 asks the question, "Is RED LED2 flashing?". If low-pressure switch was defective, a low-	6	7	Ð
		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.	Ð	Ð	INDEX

Step 1ÐSelf-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. Then green LED comes on for 1 sec, followed by 1 sec where both yellow and green LEDs are on. During this time, the microprocessor is checking itself.

Step 2ÐHeating Mode

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

1.Prepurge periodÐThe inducer motor is turned on and 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-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 then used to determine required RPM necessary to operate inducer in high-heat mode.

2.Humidifier (HUM)ÐThe HUM terminal is energized whenever the inducer prepurge period is completed.

3.Ignitor warm upÐAt end of prepurge period, the hot surface ignitor (HSI) is energized for a 17-sec HSI warm-up period.

4.Ignition sequenceÐAfter HSI ignitor warm-up period is completed, the gas valve opens, permitting gas flow 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 lowand 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 result of thermostat operating time. See Appendix G for details on thermostat staging algorithm.

5.Flame sensingÐWhen 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 reductionÐIf 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 delayÐThe 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 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 proper airflow for heating mode.

8.Electronic Air CleanerÐThe EAC-1 terminal is energized whenever the blower operates.

9.Blower off delayÐWhen thermostat is satisfied, 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 off time selection). The furnace is factory set for a 90 sec blower off delay.

10.Post purgeÐThe inducer continues operating for 15 sec after gas valve is de-energized.

Step 3ÐHeating ModeÐTwo 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 4ÐEmergency 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.

2

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 periodÐThe inducer motor is turned on IMMEDIATELY operating at maximum speed, closing lowand high-pressure switches. Prepurge begins 25 sec after highpressure switch closes.

2.Blower onÐThe 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 CleanerÐThe EAC-1 terminal does not operate in emergency heat mode.

4.HumidifierÐThe HUM terminal is energized IMMEDIATELY.

5.Ignitor warm upÐThe HSI is energized for a 17 sec warm-up period after prepurge period is completed.

6.Ignition sequenceÐAfter HSI warm-up period has completed, the gas valve is energized, permitting gas flow to burners where it is ignited. After 5 sec, the HSI is de-energized and a 2-sec flame-sensing period begins.

NOTE: Emergency heat mode only operates in high heat.

7.Flame sensingÐWhen 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 off delayÐWhen thermostat is satisfied, 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 purgeÐPost purge does NOT occur. The inducer stops immediately.

Step 5ÐCooling Mode

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

1.Cooling unitÐThe cooling unit starts when thermostat R-Y signal is received.

2.Blower onÐThe 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, the microprocessor 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 CleanerÐThe EAC-1 terminal is energized whenever blower operates.

4.Cooling unitÐThe cooling unit stops when thermostat R-Y signal is terminated.

5.Blower off delayÐWhen 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 6ÐHeat 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 periodÐThe inducer motor is turned on and 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, 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.HumidifierÐThe HUM terminal is energized whenever inducer prepurge period is completed.

3.Ignitor warm upÐAfter prepurge period, HSI is energized for 17 sec.

4.Ignition sequenceÐAfter 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 sensingÐWhen 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 periodÐTen sec after gas valve is energized, the blower stops for 25 sec to allow heat exchangers to warm up.

7.Blower on delayÐAfter blower off period, blower starts.

NOTE: The blower starts at approximately 400-500 RPM. After 20 sec, the motor 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 proper airflow for heating mode.

8.Electronic Air CleanerÐThe EAC-1 terminal is energized whenever blower operates.

9.Inducer speed reductionÐIf 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.

10.Call for heat terminatedÐWhen 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 presentÐThe blower changes its speed to cooling RPM.

3

		HUM
		G
		R
		Y/Y2
		W/W1
		Com	24V
		W2
SEC-2	SEC-1	DEHUM

		HUM
		G
		R
		Y/Y2
		W/W1
		Com	24V
		W2
		DE
SEC-2	SEC-1	DEHUM

DE CONNECTION

WITHOUT DE	WITH DE
CONNECTION	CONNECTION

A98293

Fig. 1ÐVariable Speed Furnace Control

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

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

11.Post purgeÐThe inducer continues operating for 15 sec after gas valve is de-energized.

Step 7ÐContinuous Fan Mode

1.Operating with continuous fan only.

a.Call for continuous fanÐThe thermostat closes R-G circuit.

b.Blower onÐThe blower starts immediately.

NOTE: The blower starts at approximately 400-500 RPM. After 20 sec, the motor 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 proper airflow for heating mode.

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 CleanerÐThe EAC-1 terminal is energized whenever blower operates, regardless of operating mode.

2.Operating with continuous fan (R-G) and call for heat (R-W/W1) is receivedÐSame 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 receivedÐSee Cooling Mode section. After call

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

Step 8ÐComponent 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 panel door 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.

4

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-6 to OFF and then back to ON.

After component test, perform the following:

1.Release blower panel 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 9ÐBypass 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.

VARIABLE-SPEED

THERMIDISTAT CONDENSING FURNACE

24 VAC HOT

R

R

		DEHUM
DEHUMIDIFY	DHUM	Com
24 VAC COMM	C

A98294

Fig.2ÐWithout DE Connection

Step 10ÐDehumidification 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 speed furnace 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

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 between the thermidistat or humidistat control and furnace. The relay coil is connected between DHUM output on the thermidistat control and COM terminal on the furnace control or the humidistat output and COM 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			CONDENSING
				FURNACE
24 VAC HOT	R						R
DEHUMIDIFY	DHUM						DEHUM
							DE
						NOTE 1
24 VAC COMM	C					Com

NOTE 1 - Remove DE Connection

To Enable DEHUM Input

A98295

Fig. 3ÐWith DE Connection

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 11ÐZone 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 blower is operating in 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.

5

START HEREÐIf a problem exists, the service technician should always begin troubleshooting here.

	STEP	ACTION	YES	NO	GO TO
	1.	Remove furnace door first. DO NOT REMOVE BLOWER ACCESS PANEL! Record status of LED's	Ð	Ð	2
		1-4. See Service Label/Fault Code Instructions (Fig.4).
	2.	Are any LEDs flashing?	5	3	Ð
	3.	Are any LEDs on solid? (Solid means ON continuously.)	4	8	Ð
	4.	Go to page number indicated in Index for LEDs 1, 2, 3, or 4 ON SOLID.	Ð	Ð	INDEX
	5.	Is RED LED2 flashing?	6	7	Ð
	6.	Go to page number indicated in Index for RED LED2 FLASHING.	Ð	Ð	INDEX
	7.	Go to page number indicated in Index for subsection covering fault code being flashed.	Ð	Ð	INDEX
	8.	Is power on? (DO NOT cycle power to unit).	10	9	Ð
	9.	Turn power on.	Ð	Ð	20
	10.	Remove blower access panel and depress door switch. Use a piece of tape to hold switch closed.	Ð	Ð	11
		Wait a few sec for self test before proceeding to next step.
	11.	Does problem appear to be low cooling airflow?	12	13	Ð
	12.	Go to page number indicated in Index for subsection covering NOT ENOUGH COOLING AIRFLOW.	Ð	Ð	INDEX
	13.	Make sure thermostat is calling for heat.	Ð	Ð	14
	14.	Make sure thermostat fan control is in AUTO position if equipped.	Ð	Ð	15
	15.	Observe operation of furnace for 20 minutes or until fault occurs.	Ð	Ð	16
	16.	Does a fault occur?	7	17	Ð
	17.	Is temperature rise below range specified on rating plate when unit is running in high fire?	18	19	Ð
	18.	Go to page number indicated in Index for subsection	Ð	Ð	INDEX
		covering HIGH FIRE TEMPERATURE RISE TOO LOW (COLD BLOW).
	19.	Does furnace operate properly?	31	28	Ð
	20.	Remove blower access panel and depress door switch. Use a piece of tape to hold switch closed.	Ð	Ð	21
		Wait a few sec for self test before proceeding to next step.
	21.	Disconnect R thermostat lead, then wait until blower motor stops.	Ð	Ð	22
	22.	Are any LEDs flashing?	24	23	Ð
	23.	Are any LEDs on solid? (Solid means ON continuously.)	4	25	Ð
	24.	Is RED LED2 flashing?	6	7	Ð
	25.	Put setup switch SW-1 in ON position.	Ð	Ð	26
		Record fault codes listed in fault history.
	26.	NOTE: Read fault codes until they repeat. The last fault code that occurred will flash first fol-	Ð	Ð	27
		lowed by the lowest number fault code. (EXAMPLE: 13, 13, 44)
	27.	Are LEDs 3 and 4 flashing a Fault Code 11?	29	30	Ð
	28.	Go to page number indicated in Index for subsection covering NO OPERATION WITH NO FLASH-	Ð	Ð	INDEX
		ING FAULT CODE.
	29.	Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS.	Ð	Ð	INDEX
	30.	Go to page number indicated in Index for subsection covering first fault code flashed.	Ð	Ð	INDEX
	31.	Disconnect the R thermostat lead, then wait until blower motor stops.	Ð	Ð	32
	32.	Put setup switch SW-1 in ON position.	Ð	Ð	33
		Record fault codes listed in fault history.
	33.	NOTE: Read fault codes until they repeat. The last fault code that occurred will flash first fol-	Ð	Ð	34
		lowed by the lowest number fault code. (EXAMPLE: 13, 13, 44)
	34.	Are LEDs 3 and 4 flashing a Fault Code 11?	35	30	Ð
	35.	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	Ð	Ð	INDEX
		an intermittent basis after replacing furnace control board, contact your distributor.

6

	SERVICE
LED CODE	STATUS
RED LED1 ON	Furnace is operating in emergency heat.
RED LED2 ON	The microprocessor has malfunctioned. To reset: Put setup switch "SW-1" in the "ON"
	position and jumper thermostat terminals "R", "W/W1", and "Y/Y2" simultaneously with
	the door switch pushed in and power to the unit "ON". Disconnect jumper and place
YELLOW LED3 ON	setup switch in the "OFF" position. IfLED2 reappears replace main control board.
	Furnace is operating in high heat.
GREEN LED4 ON	Furnace is operating in lowheat.
RED LED2 FLASHING	Line voltage polarity is reversed.

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.

11NO FAULT IN RECENT HISTORY DISPLAY - Indicates no faults have occurred within last five cycles. To read recent fault history put setup switch "SW-1" in the "ON" position. To clear recent fault

history, put setup switch "SW-1" in the "ON" position and jumper thermostat terminals "R", "W/W1", and "Y/Y2" simultaneously until an "11" is flashed.

12BLOWER CALIBRATION LOCKOUT - Indicates RPM calculated for low heat was 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.

13LIMIT 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 LOCKOUT - Control will auto-reset after three hours. Refer to #34.

21INVALID MODEL SELECTION - Indicates model plug is missing or incorrect. See wiring diagram for correct connector jumper location.

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

23INVALID 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.

24SECONDARY VOLTAGE FUSE IS OPEN

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

31 HIGH PRESSURE 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-Calibration" pressure switches.

32LOW PRESSURE SWITCH FAULT - Indicates low pressure switch 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-Calibration" pressure switches.

33LIMIT OR FLAME ROLL-OUT SWITCH IS OPEN - Indicates the limit, rollout switch or auxiliary limit switch is open or the unit is operating in high heat only mode due to two successive low heat

limit trips. Check for: - Improper or misaligned limit and/or limit shield.

-Improper low heat gas input adjustment.

-Stuck high heat solenoid in gas valve.

A99243a

7

34IGNITION PROVING FAULT - Control will try three more times before a lockout #14 occurs. Check for: - Gas valve defective or gas valve turned "OFF".

- Defective Hot Surface Ignitor	- Manual valve shut-off.
- Low inlet gas pressure	- Flame sensor must be ungrounded.

-Green wire MUST be connected to furnace sheet metal.

-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 - Oxide buildup on flame sensor (clean with fine steel wool.)

41BLOWER 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.

42INDUCER OUTSIDE 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 guide.

43PRESSURE SWITCH CALIBRATION FAULT- Indicates the low and high pressure switch "make" points during high heat purge are not within the calibration 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.

44BLOWER CALIBRATION FAULT - Indicates the calculated blower speed is below 250 or above 1300 RPM. Unit will default to low or 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 itself check for undersized ductwork, or excessive static caused by a dirty filter, or closed registers.

STATUS CODE EXAMPLE

		RED LED1			RED LED2
		EMER HEAT			MICROPROCESSOR
					MALFUNCTION
8)-SW,(SW1 SETUP	OFF	1		1
		OFF OFF 8 7 6 5 4 3 2	3 2 1 3 2 1
				2
				3	DEHUM
				4	FUSE	DE	W2	COM	W/W1 Y/Y2	R	G
								24 V

YELLOW LED3		COUNT THE NO.			COUNT THE NO.
		OF FLASHES
					OF FLASHES
HIGH HEAT

GREEN LED4				(4)			(2) =		42 FAULT
LOW HEAT									INDUCER OUTSIDE VALID
									SPEED RANGE

COMPONENT TEST

To initiate the component test sequence, shut "OFF" the room thermostat or disconnect the "R"
thermostat lead. Put setup switch "SW-6" in the "ON" position to start the component test sequenceHUM			.
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 motor tested	OK. Visual check of hot surface ignitor required.
22	SETUP ERROR - Same as code 22 above.

41BLOWER OUTSIDE VALID SPEED RANGE - Indicates blower motor failed test. Check blower, wiring, and control center.

42INDUCER OUTSIDE VALID SPEED RANGE - Indicates inducer motor failed test. Check inducer, wiring and control center.

To repeat component test turn setup switch "SW-6" "OFF" and then back "ON". After component test is completed put setup switch "SW-6" in the "OFF" position and reconnect the "R" thermostat lead.

320624-101 REV. J

A99243

A99243b

→Fig. 4ÐService Label/Fault Code Instructions

8

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

	STEP	ACTION	YES	NO	GO TO
	1.	Make sure power is on.	Ð	Ð	2
	2.	Remove blower access panel and depress door switch. Use a piece of tape to hold switch closed.	Ð	Ð	3
		Wait a few sec for self test before proceeding to next step.
	3.	Make sure thermostat is calling for heat.	Ð	Ð	4
	4.	Make sure thermostat fan control is in AUTO position if equipped.	Ð	Ð	5
	5.	Check fuses, breakers, or manual disconnects to be sure they are correctly set.	Ð	Ð	6
	6.	Does 120-v wiring match unit wiring schematic?	9	7	Ð
	7.	Fix problem.	Ð	Ð	8
	8.	Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS.	Ð	Ð	INDEX
	9.	Do you have 120 vac at primary leads P1 and P2 on furnace control board?	14	10	Ð
	10.	Do you have 120 vac to furnace control board?	11	12	Ð
	11.	Check all 120-vac connections at furnace control board. If necessary, replace furnace control board.	Ð	Ð	8
	12.	Turn power off.	Ð	Ð	13
	13.	Check continuity of power supply leads and door switch if wired with 120 vac.	Ð	Ð	7
	14.	Do you have 24v between SEC-1 and SEC-2 on furnace control board?	19	15	Ð
	15.	Turn power off.	Ð	Ð	16
	16.	Do you have continuity across door switch?	17	18	Ð
	17.	Replace transformer. If transformer fails again, replace transformer and furnace control board.	Ð	Ð	8
	18.	Replace door switch.	Ð	Ð	8
	19.	Do you have 24v between R and Com on furnace control board?	21	20	Ð
	20.	Replace furnace control board.	Ð	Ð	8
	21.	Do you have 24v between W/W1 and Com on furnace control board?	24	22	Ð
	22.	Check to see that thermostat is calling for heat.	Ð	Ð	23
	23.	You have a defective thermostat or a break in the wiring between thermostat and furnace.	Ð	Ð	7
	24.	Does furnace respond to the call for heat?	27	25	Ð
	25.	Turn power off.	Ð	Ð	26
	26.	Press down on microprocessor chip and make sure it is properly seated to furnace control board. If	Ð	Ð	7
		it is, replace furnace control board.
	27.	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	28	34	Ð
		then cycle repeats.
	28.	Disconnect BROWN wire to gas valve GV.	Ð	Ð	29
	29.	Does furnace still alternately cycle inducer motor, go through a self test, and then run blower motor	30	37	Ð
		as described in Step 27?
	30.	Disconnect humidifier lead from HUM terminal on furnace control board.	Ð	Ð	31
	31.	Does furnace still alternately cycle inducer motor, go through a self test, and then run blower motor	33	32	Ð
		as described in Step 27?
	32.	There is a direct short in wiring to humidifier solenoid coil, or short is inside humidifier solenoid coil.	Ð	Ð	7
	33.	There is a direct short in either the pressure switch circuits, gas valve GV, or wiring to gas valve	Ð	Ð	7
		GV. If hot surface ignitor comes on during the cycle, short is in gas valve or wiring to gas valve.
	34.	Does furnace ever abruptly shut down with no fault code, no inducer post purge, no blower off de-	35	38	Ð
		lay, and then restart heating cycle?
	35.	Disconnect BROWN wire to gas valve GV.	Ð	Ð	36
	36.	Does furnace still abruptly shut down with no fault code, no inducer post purge, no blower off delay,	39	37	Ð
		and then restart heating cycle?
	37.	Replace gas valve.	Ð	Ð	8
	38.	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 replac-	Ð	Ð	INDEX
		ing furnace control board, contact your distributor.
	39.	Disconnect humidifier lead from HUM terminal on furnace control board.	Ð	Ð	40
	40.	Does furnace still abruptly shut down with no fault code, no inducer post purge, no blower off delay,	33	32	Ð
		and then restart heating cycle?

9

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

	STEP	ACTION	YES	NO	GO TO
	1.	Remove blower access panel and depress door switch. Use a piece of tape to hold switch closed.	Ð	Ð	2
		Wait a few sec for self test before proceeding to next step.
	2.	Make sure thermostat is calling for cooling. If thermostat lead G is not connected, jumper across	Ð	Ð	3
		thermostat terminals R and G.
	3.	Make sure thermostat fan control is in AUTO position if equipped.	Ð	Ð	4
	4.	Do you have 24v across Y/Y2 and Com on furnace control board?	8	5	Ð
	5.	You have a defective thermostat, or a break in wiring between thermostat and furnace, or the Y/Y2	Ð	Ð	6
		thermostat terminal is not wired to thermostat.
	6.	Fix problem.	Ð	Ð	7
	7.	Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS.	Ð	Ð	INDEX
	8.	Are air conditioning select switches A/C set to proper tonnage as required by condensing unit? (See	10	9	Ð
		Table 1.)
	9.	Set air conditioning select switches A/C for proper tonnage as required by condensing unit. (See	Ð	Ð	7
		Table 1.)
	10.	Disconnect the G thermostat lead or jumper if used.	Ð	Ð	11
	11.	Does blower motor turn off in 90 sec when G thermostat lead is disconnected?	12	13	Ð
	12.	Replace furnace control board.	Ð	Ð	7
	13.	Observe operation of furnace in cooling mode for 8 minutes.	Ð	Ð	14
	14.	Does furnace operate properly in cooling mode?	15	16	Ð
		Make sure outdoor unit is properly charged. If it is, go to page number indicated in Index for
	15.	CLEANUP AND START-UP INSTRUCTIONS. If problem persists on an intermittent basis, replace	Ð	Ð	INDEX
		furnace control board. If problem still persists after replacing furnace control board, contact your dis-
		tributor.
	16.	Does furnace abruptly go through a self-test sequence as blower comes up to speed?	17	24	Ð
	17.	Do you have less than 17 vac between R and Com on furnace control board?	18	24	Ð
	18.	Do you have less than 90 vac between P1 and P2 on furnace control board?	19	20	Ð
	19.	Make sure the wire gage between main fuse box and furnace complies with wire size specification	Ð	Ð	6
		in Installation, Start-Up, and Operating Instructions.
	20.	Disconnect the R thermostat lead.	Ð	Ð	21
	21.	Do you have less than 17 vac between R and Com on furnace control board?	22	23	Ð
	22.	Replace transformer.	Ð	Ð	7
	23.	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	Ð	Ð	6
		ft. For wire lengths over 100 ft, use AWG No. 16 wire.
	24.	Press down on microprocessor chip and make sure it is properly seated to furnace control board. If	Ð	Ð	6
		it is, replace furnace control board.

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

AIR CONDITIONER

AIRFLOW

A/C SWITCH POSITION

ALLOWABLE FURNACE MODEL SETUP

(TONS)

(CFM)

A/C-1

A/C-2

A/C-3

040

060

080

080

100

120

Default

1200 or

OFF

OFF

OFF

3 Tons

3 Tons

3 Tons

5

Tons

5

Tons

5

Tons

2000

1200 CFM

1200 CFM

1200 CFM

2000 CFM

2000 CFM

2000 CFM

1-1/2

600

ON

OFF

OFF

X

X

X

Ð

Ð

Ð

2

800

OFF

ON

OFF

X

X

X

X

X

X

2-1/2

1000

ON

ON

OFF

X

X

X

X

X

X

3

1200

OFF

OFF

ON

X

X

X

X

X

X

3-1/2

1400

ON

OFF

ON

X

X

X

X

X

X

4

1600

OFF

ON

ON

Ð

Ð

Ð

X

X

X

5

2000

ON

ON

ON

Ð

Ð

Ð

X

X

X

XÐIndicates allowable selection.

10

HIGH-FIRE TEMPERATURE TOO LOWÐGenerally, 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.	Ð	Ð	2
	2.	Depress door switch. Use a piece of tape to hold switch closed. Wait a few sec for self test before	Ð	Ð	3
		proceeding to next step.
	3.	Set thermostat to call for heat or jumper R and W/W1 thermostat terminals.	Ð	Ð	4
	4.	When GREEN LED4 is ON solid, clock low-fire gas rate. You have 16 minutes on this first call for	Ð	Ð	5
		heat. On propane installations, check manifold pressure.
	5.	When YELLOW LED3 is ON solid, clock high-fire gas rate. On propane installations, check manifold	Ð	Ð	6
		pressure.
	6.	Is high-fire rate approximately same as low-fire rate?	7	11	Ð
	7.	Do you have 24 vac across gas valve terminal HI and Com on furnace control board during high	10	8	Ð
		fire?
	8.	You have an open wire or bad terminal on BROWN wire from furnace control board to gas valve	Ð	Ð	9
		GV. Repair it or replace the harness.
	9.	Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS.	Ð	Ð	INDEX
	10.	Replace gas valve.	Ð	Ð	9
	11.	Is high-fire rate within 2% of that specified on rating plate?	13	12	Ð
	12.	Ensure gas inlet pressure and burner orifices are correct, then adjust gas valve to proper rate. If it	Ð	Ð	9
		cannot be adjusted to proper rate, replace gas valve.
	13.	Check outdoor condensing unit for operation during heating cycle.	Ð	Ð	14
	14.	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,	Ð	Ð	15
		condensation may form on heat exchangers. If left uncorrected, failure will result.
	15.	Check return-air ducts in unheated spaces for leaks.	Ð	Ð	9

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.	Ð	Ð	2
	2.	Turn power on and depress door switch. Use a piece of tape to hold switch closed.	Ð	Ð	3
	3.	Jumper R and W/W1 thermostat terminals on furnace control board.	Ð	Ð	4
	4.	Is RED LED1 ON?	5	9	Ð
	5.	Is setup switch SW-4 labeled EMER. HEAT in ON position?	6	7	Ð
	6.	Put setup switch SW-4 labeled EMER. HEAT in OFF position.	Ð	Ð	8
	7.	Replace furnace control board.	Ð	Ð	8
	8.	Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS.	Ð	Ð	INDEX
	9.	Disconnect jumper wire across R and W/W1 thermostat terminals.	Ð	Ð	10
	10.	Is RED LED2 ON?	11	32	Ð
	11.	Do you have less than 17 vac between R and Com on furnace control board?	12	19	Ð
	12.	Do you have less than 90 vac between P1 and P2 on furnace control board?	13	15	Ð
	13.	Make sure wire gage between main fuse box and furnace complies with wire size specification in	Ð	Ð	14
		Installation, Start-Up, and Operating Instructions.
	14.	Fix problem.	Ð	Ð	8
	15.	Disconnect R thermostat lead.	Ð	Ð	16
	16.	Is RED LED2 ON?	17	18	Ð
	17.	Replace transformer.	Ð	Ð	8
	18.	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	Ð	Ð	14
		ft. For wire lengths over 100 ft, use AWG No. 16 wire.
	19.	Disconnect all thermostat leads from furnace control board.	Ð	Ð	20
	20.	Put setup switch SW-1 in ON position and jumper R, W/W1, and Y/Y2 thermostat terminals.	Ð	Ð	21
	21.	Does RED LED2 turn OFF?	22	7	Ð
	22.	Put setup switch SW-1 back in OFF position.	Ð	Ð	23
	23.	Turn power off and reconnect thermostat leads to furnace control board.	Ð	Ð	24
	24.	Turn power on.	Ð	Ð	25
	25.	Does RED LED2 turn back ON?	26	36	Ð
	26.	Disconnect all thermostat leads from thermostat control board.	Ð	Ð	27
	27.	Put setup switch SW-1 in ON position and jumper R, W/W1, and Y/Y2 thermostat terminals simulta-	Ð	Ð	28
		neously until RED LED2 turns OFF.

11

	28.	Put setup switch SW-1 back in OFF position.	Ð	Ð	29
	29.	Jumper R and W/W1 thermostat terminals.	Ð	Ð	30
	30.	Does RED LED2 turn back ON?	7	31	Ð
	31.	Install isolation relays in the W/W1 and Y/Y2 circuits per Fig. 5 in Appendix B or replace thermostat.	Ð	Ð	8
	32.	Was RED LED2 ON before you started Step 1?	34	33	Ð
	33.	Solid YELLOW LED3 indicates furnace is in high fire and solid GREEN LED4 indicates furnace is in	Ð	Ð	8
		low fire.
	34.	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	Ð	Ð	35
		outdoor unit may solve problem. (See Fig. 6 in Appendix B.)
	35.	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	Ð	Ð	14
		ft, use AWG No. 16 wire.
	36.	Observe operation of furnace through a 20 minute heat cycle. Try to pinpoint where in cycle RED	Ð	Ð	37
		LED2 turns ON.
		Go to step indicated below if RED LED2 turns ON when 1 of the following events occur:	Ð	Ð	Ð
		· When gas valve is energized.	Ð	Ð	38
	37.	· When HSI is energized.	Ð	Ð	39
		· When high-pressure switch HPS makes during transition from low to high fire.	Ð	Ð	38
		· RED LED2 never turns ON.	Ð	Ð	40
	38.	Replace gas valve.	Ð	Ð	8
	39.	Isolate humidifier with a separate 24-vac supply or replace humidifier solenoid coil.	Ð	Ð	14
	40.	Observe operation of furnace through a 4 minute cooling cycle. Does RED LED2 turn ON?	41	47	Ð
	41.	Disconnect all thermostat leads from furnace control board.	Ð	Ð	42
	42.	Put setup switch SW-1 in ON position and jumper R, W/W1, and Y/Y2 thermostat terminals simulta-	Ð	Ð	43
		neously until RED LED2 turns OFF.
	43.	Put setup switch SW-1 back in OFF position.	Ð	Ð	44
	44.	Reconnect only outdoor unit to Y/Y2 and Com terminals on furnace control board.	Ð	Ð	45
	45.	Jumper R and Y/Y2 thermostat terminals.	Ð	Ð	46
	46.	Does RED LED2 turn back ON?	34	31	Ð
	47.	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 inter-	Ð	Ð	INDEX
		mittent basis after replacing furnace control board, contact your distributor.

RED LED2 FLASHINGÐIndicates line voltage polarity is reversed.

	STEP	ACTION	YES	NO	GO TO
	1.	Turn power off, remove blower access panel, and disconnect all thermostat leads from furnace con-	Ð	Ð	2
		trol board.
	2.	Turn power on and depress door switch. Use a piece of tape to hold switch closed.	Ð	Ð	3
	3.	Is RED LED2 flashing?	6	4	Ð
	4.	Replace furnace control board, date code 9405 or later.	Ð	Ð	5
	5.	Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS.	Ð	Ð	INDEX
	6.	Do you have 120 vac across L2 and chassis ground?	7	8	Ð
	7.	Line voltage polarity is reversed. Fix problem.	Ð	Ð	5
	8.	Replace furnace control board.	Ð	Ð	5

12

Fault Code 11

NO FAULT IN RECENT HISTORY DISPLAYÐThis 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.	Ð	Ð	2
	2.	Is setup switch SW-1 in ON position?	3	5	Ð
	3.	Put setup switch SW-1 in OFF position.	Ð	Ð	4
	4.	Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS.	Ð	Ð	INDEX
	5.	Is setup switch SW-6 in ON position.	6	7	Ð
	6.	Put setup switch SW-6 in OFF position.	Ð	Ð	4
	7.	Jiggle setup switches SW-1 and SW-6 back and forth. If Fault Code 11 continues to flash, replace	Ð	Ð	4
		furnace control board.

Fault Code 12

BLOWER CALIBRATION LOCKOUTÐThis 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
	1.	Turn power off, wait 30 sec, and then restore power. Reset thermostat. Observe operation of fur-
		nace through 1 heating cycle.	Ð	Ð	2
		NOTE: Blower access panel must be in place.
	2.	Does only Fault Code 44 flash?	40	6	Ð
	3.	The problem is excessive restriction in the air delivery system. Check filters and ductwork. Use Ap-	Ð	Ð	4
		pendix E to evaluate.
	4.	Fix problem.	Ð	Ð	5
	5.	Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS.	Ð	Ð	INDEX
	6.	Does Fault Code 44 flash twice followed by Fault Code 41?	9	7	Ð
	7.	Does a different fault occur?	8	39	Ð
	8.	Go to page number indicated in Index for fault code flashed.	Ð	Ð	INDEX
	9.	Turn power off and remove blower access panel.	Ð	Ð	10
	10.	Are all pins and wire leads intact on connectors between furnace control board and blower motor.	11	4	Ð
	11.	Depress door switch. Use a piece of tape to hold switch closed. Wait a few sec for self test before	Ð	Ð	12
		proceeding to next step.
	12.	Disconnect all thermostat leads from furnace control board and jumper R and W/W1 thermostat ter-	Ð	Ð	13
		minals.
	13.	Does blower motor turn on and come up to speed (400-500 RPM) before fault code flashes?	Ð	20	Ð
	14.	Disconnect jumper wire across R and W/W1 thermostat terminals, turn power off, and then restore	Ð	Ð	15
		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
	15.	voltage across ORANGE and VIOLET wires change between states as shown below?	16	17	Ð
		· State 1ÐOFF (12.0Ð12.5 vdc)
		· State 2ÐLOW (10.7Ð11.7 vdc)
		· State 3ÐHIGH(9.7Ð10.7 vdc)
	16.	Replace furnace control board.	Ð	Ð	5
	17.	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 ap-	18	19	Ð
		proximately the same DC voltages across ORANGE and VIOLET wires that you saw in Step 15?
	→18.	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,	Ð	Ð	4
		find source of water and fix. Check A-coil and/or humidifier.

13

	19.	You have an open wire or bad terminal on either the ORANGE or VIOLET wire between connectors		Ð	Ð	5
		PL13 and PL3. Repair it or replace blower harness(es).
	20.	Remove tape from door switch and turn power off at main disconnect.		Ð	Ð	21
	21.	Does blower wheel rub against blower housing?		4	22	Ð
	22.	Does blower wheel turn freely?
	23.	Is blower wheel firmly mounted on motor shaft?		25	4	Ð
	→24.	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,		Ð	Ð	4
		find source of water and fix. Check A-coil and/or humidifier.
	25.	Disconnect jumper wire across R and W/W1 thermostat terminals.		Ð	Ð	26
	26.	Turn power back on. Depress door switch. Use a piece of tape to hold switch closed. Wait a few		Ð	Ð	27
		sec for self test before proceeding to next step.
	27.	Do you have 120v between B1 and B2 on furnace control board?		28	4	Ð
	28.	Do you have 120v between BLACK and WHITE power leads at blower motor MTR2?		30	29	Ð
	29.	You have an open wire or bad terminal on either the BLACK or WHITE wire between furnace con-		Ð	Ð	5
		trol board and blower motor MTR2.
		Check blower ON/OFF line. To do this, connect a DC voltmeter across terminals PL3-1 RED (+)
	30.	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?		32	31	Ð
		·	State 1ÐOFF (-0.1 Ð 0.1 vdc)
		·	State 2ÐON (9.0 Ð 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
	31.	SW-6 OFF and then back ON. Does voltage across PL3-1 and PL3-5 change between states as		18	16	Ð
		shown below?
		·	State 1ÐOFF (-0.1 Ð 0.1 vdc)
		·	State 2ÐON (11.0 Ð 12.0 vdc)
	32.	Connect a DC voltmeter across RED (+) and BLUE (-) wires at connector PL13 then repeat COM-
		PONENT TEST by turning setup switch SW-6 OFF and then back ON. Do you see approximately		34	33	Ð
		the same DC voltages across RED and BLUE wires that you saw in Step 30?
	33.	You have an open wire or bad terminal on either the RED or BLUE wire between connectors PL13		Ð	Ð	5
		and PL3. Repair it or replace blower harness(es).
	34.	Put setup switch SW-6 for COMPONENT TEST in OFF position.		Ð	Ð	35
		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 volt-
	35.	age across the RED and YELLOW wires change between states as shown below?		37	36	Ð
		·	State 1ÐOFF (-0.1 Ð 0.1 vdc)
		·	State 2ÐLOW (2.5 Ð 3.0 vdc)
		·	State 3ÐHIGH (7.0 Ð 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
	36.	SW-6 OFF and then back ON. Does voltage across PL3-1 and PL3-4 change as shown below?		18	16	Ð
		·	State 1ÐOFF (-0.1 Ð 0.1 vdc)
		·	State 2ÐLOW (3.0 Ð 4.0 vdc)
		·	State 3ÐHIGH (9.0 Ð 10.0 vdc)
	37.	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 approxi-		18	38	Ð
		mately the same DC voltages across RED and YELLOW wires that you saw in Step 35?
	38.	You have an open wire or bad terminal on either the RED or YELLOW wire between connectors		Ð	Ð	5
		PL13 and PL3. Repair it or replace blower harness(es).
	39.	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		Ð	Ð	INDEX
		basis after replacing blower motor, contact your distributor.
	40.	Turn power off and remove blower access panel. Depress door switch. Use a piece of tape to hold		Ð	Ð	41
		switch closed. Wait a few sec for self test before proceeding to next step.
	41.	Disconnect all thermostat leads from furnace control board. If blower motor is running, wait until it		Ð	Ð	42
		stops.
	42.	Jumper R and G thermostat terminals. Observe operation of furnace for next 30 sec.		Ð	Ð	43
		Approximately 20 sec after energizing G thermostat terminal, does blower motor pause briefly (less
	43.	than1/2 sec?)		3	18	Ð
		Note:You can verify this pause using a clamp-on ammeter on BLACK power lead to blower
		motor MTR2.

14

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.	Ð	Ð	45
	→45.	Disconnect PL10 from blower assembly.	Ð	Ð	46
	→46.	Remove control box assembly from blower shelf and position out of the way.	Ð	Ð	47
	→47.	Remove blower assembly from furnace.	Ð	Ð	48
	→48.	Disconnect both multi-pin connectors from blower control module attached to the blower motor. Be	Ð	Ð	49
		sure to depress release latches on connectors or they may get damaged.
	→49.	Remove two 1/4-in. hex head bolts from blower control module attached to blower motor. DO NOT	Ð	Ð	50
		REMOVE TORX HEAD SCREWS located next to 1/4-in. hex head bolts.
	→50.	Carefully lift blower control module off blower motor. Depress latch on internal connector to discon-
		nect blower control module from motor portion of blower motor. DO NOT PULL ON WIRES. GRIP	Ð	Ð	51
		PLUG ONLY.
		When blower control module is completely detached from blower motor, verify with standard ohm-
		meter that the resistance from each motor lead in motor plug to unpainted motor end plate is
	→51.	greater than 100k ohms. Then verify motor windings are not shorted or open by measuring resis-	Ð	Ð	52
		tance 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.
	→52.	Did the motor pass the resistance check?	53	55	Ð
	→53.	Does blower wheel turn freely with blower control module removed?	54	55	Ð
	→54.	Replace blower control module. Inspect failed blower control module for water damage. If present,	Ð	Ð	5
		find source of water and fix. Check A-coil and/or humidifier.
	→55.	Replace entire blower motor including blower control module. Inspect blower control module for wa-	Ð	Ð	5
		ter damage. If present, find source of water and fix. Check A-coil and/or humidifier.

Fault Code 13

LIMIT SWITCH LOCKOUTÐThis 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
	1.	Turn power off and remove blower access panel. Disconnect all thermostat leads from furnace con-	Ð	Ð	2
		trol board.
	2.	Depress door switch. Use a piece of tape to hold switch closed.	Ð	Ð	Ð
	3.	Put setup switch SW-1 in ON position.	Ð	Ð	4
		Is a Fault Code 44 present in the fault history.
	4.	NOTE: Read fault codes until they repeat. The last fault code that occurred will flash first fol-	46	5	Ð
		lowed by the lowest number fault code. (EXAMPLE: 13, 13, 44)
	5.	Put setup switch SW-1 in OFF position.	Ð	Ð	42
	6.	Does furnace have proper limit switch, limit shield, blower baffle (if used), and rear air baffle (if	10	48	Ð
		used)? If so are limit switch, limit shield, and heat exchangers properly aligned?
	7.	Replace limit switch.	Ð	Ð	9
	8.	Replace furnace control board.	Ð	Ð	9
	9.	Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS.	Ð	Ð	INDEX
	10.	Put setup switch SW-2 in ON position.	Ð	Ð	11
	11.	Jumper R and W/W1 thermostat terminals on furnace control board.	Ð	Ð	12
	12.	Is furnace considerably overfired (10% or more)? Clock input rate. Do not use manifold pressure	13	14	Ð
		method unless using propane.
	13.	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	Ð	Ð	9
		proper rate, replace gas valve.
	14.	Is the personality connector PL5 properly wired per furnace model sizing chart in upper left-hand	50	15	Ð
		corner of wiring schematic?
	15.	Replace or rewire personality connector.	Ð	Ð	9

15