ICP 9MAC/E Troubleshooting Manual

Variable Speed, Modulating

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Electronic Condensing

Four-Way Multipoise Gas Furnace

*9MAC(

TROUBLESHOOTING GUIDE

INDEX

PAGE

Safety Considerations..............................................................................1

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

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

General.....................................................................................................2

Sequence of Operation ............................................................................2

Communicating Control and Modulating Heating......................... 2

Single-Stage Thermostat and Modulating Heating (Adaptive

Mode)......................................................................................3

Two-Stage Thermostat and Two-Stage Minimum/Maximum

Heating ....................................................................................4

Two-Stage Thermostat and Two-Stage Intermediate/Maximum

Heating ....................................................................................4

Cooling Mode..................................................................................5

Single-Speed Cooling .....................................................................5

Two-Stage Thermostat and Two-Speed Cooling............................ 5

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

Super-Dehumidify Mode ................................................................5

Continuous-Blower Mode...............................................................6

Heat Pump Defrost..........................................................................6

Component Test ..............................................................................6

Service/Status Code Instructions.............................................................7

Start Here.................................................................................................9

Amber LED On Solid............................................................................10

Improper Cooling Air Flow...................................................................11

Minimum and/or Maximum Heat Temperature Rise Too Low............13

Secondary Voltage Fuse Open ..............................................................14

Status Code 2 - Pressure Switch Did Not Open....................................16

Status Code 3 - Low Pressure Switch Did Not Close or Reopened ..... 17

Status Code 4 - Limit Circuit Fault.......................................................19

Status Code 5 - Abnormal Flame-Proving Signal.................................21

Status Code 6 - Ignition-Proving Fault .................................................21

Status Code 7 - Limit Circuit Lockout..................................................23

Status Code 8 - Gas Heating Lockout ...................................................24

Status Code 9 - Medium Pressure Switch, High Pressure Switch, or

PSR Relay did not Close or Reopened.........................................24

Status Code 10 - Polarity....................................................................... 27

Status Code 1 + 2 - Blower On After Power Up...................................28

Status Code 1 + 5 - Blower Motor Lockout..........................................28

Status Code 2 + 5 - Model Selection or Setup Error ............................29

Status Code 3 + 5 - Gas Valve Fault.....................................................30

Status Code 4 + 1 - Blower Motor Fault...............................................32

Status Code 4 + 2 - Inducer Motor Fault .............................................. 34

Status Code 4 + 3 - Low or Medium Pressure Switch Open While

Medium or High Pressure Switch Is Closed................................. 36

Status Code 6 + 1 - Ignition Lockout....................................................37

Cleanup and Start-Up Instructions........................................................37

APPENDIX A - Board Layout & Wiring Schematic........................... 38

APPENDIX B - ECM Blower Motor Description & Operation..........40

APPENDIX C - Pressure Check Diagram............................................ 42

APPENDIX D - Static Pressure Reading Location Diagrams..............43

APPENDIX E - Quick Reference Information..................................... 45

APPENDIX F - Furnace Staging Algorithm ........................................ 46

SAFETY CONSIDERATIONS

Installing and servicing heating equipment can be hazardous due to gas and electrical components. Only trained and qualified personnel should install, repair, or service heating equipment.

Untrained personnel can perform basic maintenance functions such as cleaning coils, or cleaning and replacing filters. All other operations should be performed by trained service personnel. When working on heating equipment, observe precautions in literature, on tags, and on labels attached to or shipped with the unit, and other safety precautions that may apply.

Follow all safety codes. In the United States, follow all safety codes including the National Fuel Gas Code (NFGC) NFPA 54-2006/ANSI Z223.1-2006. In Canada, refer to the National Standard of Canada Natural Gas and Propane Installation Codes (NSCNGPIC), CSA B149.1-05.

Wear safety glasses and work gloves. Have a fire extinguisher available during start-up, adjustment procedures, and service calls.

Recognize safety information. This is the safety-alert symbol . When you see this symbol on the furnace and in instructions or manuals, be alert to the potential for personal injury.

Understand the signal words DANGER, WARNING, and CAUTION, and NOTE. The words DANGER, WARNING, and CAUTION are used with the safety-alert symbol. DANGER identifies the most serious hazards which will result in severe personal injury or death. WARNING signifies hazards which could result in personal injury or death. CAUTION is used to identify unsafe practices which may result in minor personal injury, or product and property damage. NOTE is used to highlight suggestions which will result in enhanced installation, reliability, or operation.

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 modulating furnace control was designed with diagnostic capabilities built in. A AMBER LED is used to flash a status code which will lead you to one of the sections as listed in the Index.

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You should ALWAYS begin in the START HERE section (see

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Index for page number) which will guide you to the appropriate

to the step indicated in the YES column. If the answer is NO, go to

the step indicated in the NO column. section where a minimal number of steps will be used to correct the problem. Once in a section, read the ACTION. An ACTION may have a number in the GO TO column. Do whatever the ACTION says, then proceed to the step indicated in the GO TO 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 the contacts will not open). This is an internal

problem and cannot simply be seen. We go to the START HERE If the ACTION is a question (a question will have a number in the

section to Step 1. YES or NO column), answer it YES or NO. If the answer is YES, go

EXAMPLE

Start Here Section

STEP ACTION YES NO GO TO

1. Step 1 tells us NOT TO REMOVE THE BLOWER DOOR. It then asks the question, “Is

2 19 AMBER LED status light ON SOLID, alternately flashing bright-dim-bright-dim like a heartbeat, or flashing ON and OFF?”. If the low pressure switch was defective, a pressure switch did not open status code would be flashing, so the answer is YES. We go to Step 2.

2. Step 2 asks the question, “Is the AMBER LED status light ON SOLID?”. If the low pressure

3 4 switch was defective, a pressure switch did not open status code would be flashing, so the answer is NO. We go to Step 4.

4. Step 4 asks the question, “Is the AMBER LED status light alternately flashing bright-dim-

7 5 bright-dim like a heartbeat?”. If the low pressure switch was defective, a pressure switch did not open status code would be flashing, so the answer is NO. We go to Step 5.

5. Step 5 tells us to determine the status code. The status code is a single or two digit number with the first number determined by the number of short flashes and the second number after the (+) sign is the number of long flashes. So we count the short flashes and long flashes if available and see that status code 2 is flashing and go to Step 6.

6. Step 6 tells us to go to status code 2 section. INDEX

GENERAL

The furnace must have a 115-vac power supply properly connected and grounded. Correct polarity must be maintained to enable gas heating operation.

The gas service pressure must not exceed 0.5 psig (14-in.wc), and no less than 0.16 psig (4.5-in.wc).

Thermostat wire connections to the furnace at R and W/W1 are the minimum required for gas heating operation. W2 must be connected for 2-stage heating thermostats. Y/Y2 and G are required to be connected to the furnace for single-stage cooling and heat pumps. Y1, Y/Y2, and G are required for two-stage cooling and heat pumps. G is required for continuous-fan. COM-24V is required for some clock thermostats. These connections must be made at the 24-vac terminal block on the furnace control. (See Appendix A)

This furnace can be installed with either a single-stage heat/cool or a two-stage heat/cool thermostat.

CAUTION: This furnace is equipped with a manual reset switch in the gas control area. The switch will open and shut off power to the gas valve, if a flame rollout or overheating condition occurs in the gas control area. DO NOT bypass the switch. Correct inadequate combustionair supply, or component failure before resetting the switch.

Before operating the furnace, check each manual reset switch for continuity. If necessary, press and release the button to reset the switch.

SEQUENCE OF OPERATION

Using the schematic diagram in Appendix A, follow the sequence of operation through the different modes. Read and follow the wiring diagram very carefully!!

Note: If a power interruption occurs during a call for heat (W/W1

or W/W1-and-W2), the control will start a 90-second blower-only ON period two seconds after power is restored, if the thermostat is still calling for gas heating. The amber LED light will flash code 12 during the 90-second period, after which the LED will be ON continuous, as long as no faults are detected. After the 90-second period, the furnace will respond to the thermostat normally.

The blower door must be installed for power to be conducted through the blower door interlock switch ILK to the furnace control CPU, transformer TRAN, inducer motor IDM, blower motor BLWM, hotsurface igniter HSI, and gas valve GV.

COMMUNICATING CONTROL ANDMODULATING HEATING

Best comfort will be attained when a Communicating Wall Control is used with this product. Wiring and set-up instructions are provided with the communicating control. See the furnace data sheet accessory section for help in selecting the appropriate communicating control for this furnace.

When a communicating control is used, the furnace will modulate through its full operation range, or can be limited via the minimum and maximum cfm configurations.

Operation of the furnace at the beginning and end of each heating cycle, will be the same as detailed below in the Single-Stage

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Thermostat section, EXCEPT that the communicating control will

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send modulating rate command signals through the communication bus rather than energizing the 24-v thermostat terminals.

SINGLE-STAGE THERMOSTAT AND MODULATING HEATING (ADAPTIVEMODE)

Note: Minimum-heat only switch SW1-2 selects the minimum-heat

only operation mode when ON. Intermediate-heat only switch SW42 selects intermediate-heat only operation mode when ON. If both switches are ON the furnace control will default to intermediate-heat. If either or both switches are ON the furnace control will operate at two-stages only as referenced in the Two Stage Thermostat section below. If both switches are OFF the furnace control will operate in the adaptive heating mode in response to a call for heat. When the W2 thermostat terminal is energized it will always cause maximumheat operation as long as the R to W circuit is closed, regardless of the setting of the minimum-heat or intermediate-heat only switches.

This furnace can operate as a modulating furnace with a single-stage thermostat because the furnace control CPU includes a programmed adaptive sequence of controlled operation, which selects a modulated rate between minimum- and maximum-heat. This selection is based upon the stored history of the length of previous gas-heating periods of the single-stage thermostat.

The furnace will start up in either intermediate-, or maximum-heat. The furnace will transition and operate at minimum-heat or the calculated modulating rate after starting and operating for 45 seconds at intermediate-heat. The furnace control CPU defaults to minimumheat on the first thermostat cycle and calculates the modulating rate that the furnace should run at for 19 minutes on subsequent heat cycles.

If the power is interrupted, the stored modulating rate is erased and the furnace control will select intermediate-heat for 45 seconds, minimum-heat for 19 minutes and then switch to maximum-heat, as long as the thermostat continues to call for heat. The furnace control CPU then uses this information to calculate the modulating rate the furnace will operate at on the next heating cycle. If the calculated modulating rate is between 40% - 99% then the furnace control CPU will operate for 45 seconds at intermediate-heat, and then operate at the calculated modulating rate for up to 19 minutes and then switch to maximum-heat as long as the thermostat continues to call for heat. If the calculated modulating rate is 100% then the furnace control will only operate at maximum-heat until the thermostat is satisfied.

The wall thermostat ”calls for heat”, closing the R to W circuit. The furnace control CPU performs a self-check, verifies the low, medium, and high pressure switch contacts LPS, MPS, and HPS are open, then de-energizes the PSR relay to close the NC contact.

Note: The heat cycle can start in either intermediate- or maximum-

heat. If a maximum-heat cycle is initiated, the furnace control CPU will continue to increase the inducer motor speed after the medium pressure switch MPS closes. When the medium pressure switch closes, inducer motor RPM is noted by the furnace control CPU, and a 25-second prepurge period begins. The RPM is used to evaluate vent system resistance. This evaluation is then used to determine the required RPM necessary to operate the inducer motor in maximumheat pre-purge, and maximum-heat mode. The high pressure switch HPS should be closed before ignition but the furnace control ignores this input until after ignition occurs.

2. Igniter Warm-Up - At the end of the prepurge period, the

Hot-Surface Igniter HSI is energized for a 17-second igniter warm-up period.

3. Trial-For-Ignition Sequence - When the igniter warm-up

period is completed the main gas valve relay contact GVR closes to energize the gas valve solenoid GV (pin PL17-5). The gas valve solenoid GV permits gas flow to the burners where it is ignited. Five seconds after the GVR closes, a 2-second Flame-Proving period begins. The HSI igniter will remain energized until flame is sensed or until the 2-second flame proving period begins.

4. Flame-Proving - When the burner flame is proved at the

flame-proving sensor electrode FSE, the furnace control CPU begins the blower-ON delay period and continues to hold the gas valve GV open. If the burner flame is not proved within two seconds, the furnace control CPU will close the gas valve GV, and the furnace control CPU will repeat the ignition sequence for up to three more Trials-For-Ignition before going

to Ignition-Lockout. Lockout will be reset automatically after

three hours, by momentarily interrupting 115 vac power to the furnace, or by interrupting 24 vac power at SEC1 or SEC2 to the furnace control CPU (not at W/W1, G, R, etc.).

If flame is proved when flame should not be present, the furnace control CPU will lock out of Gas-Heating mode and operate the inducer motor IDM at full speed until flame is no longer proved.

5. Inducer Speed Change – If the cycle starts in intermediate-

heat, the furnace control CPU reduces the inducer speed slightly after flame sense. If the cycle starts in maximum-heat, the furnace control CPU increases the inducer speed after flame sense.

6. Blower-On delay – If the burner flame is proven the blower-

ON delay for intermediate-heat and maximum-heat are as follows:

1. Inducer Prepurge Period - The furnace control CPU turns on

inducer motor IDM and slowly increases the inducer motor speed. After the low pressure switch LPS closes the furnace control CPU continues to increase the inducer motor speed until the medium pressure switch MPS closes. When the medium pressure switch MPS closes, inducer motor RPM is noted by the furnace control CPU, and a 25-second prepurge period begins. The RPM is used to evaluate vent system resistance. This evaluation is then used to determine the required RPM necessary to operate the inducer motor during prepurge, the first 45 seconds of intermediate-heat mode, or any modulating rate that the furnace will transition to after the blower on-delay is completed.

Intermediate-heat – 45 seconds after the gas valve GV is

opened the blower motor BLWM is turned ON at the modulating heat airflow.

Maximum-heat – 25 seconds after the gas valve GV is opened

the BLWM is turned ON at maximum-heat airflow.

Simultaneously, the humidifier terminal HUM and electronic air cleaner terminal EAC-1 are energized and remain energized throughout the heating cycle.

7. Switching fromIntermediate-Heat to a Low Range Input- If

the furnace control switches from intermediate-heat to a low

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range input (low range input is an input rate less than or equal

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to 51% of full rate, 45% of full rate on the 5T-060 model), the furnace control will turn the blower ON or switch to the modulating heat airflow, energize the PSR relay to open the NC contact, and slowly decrease the inducer motor speed to the desired inducer RPM.

Switching from Intermediate-Heat to a Medium Range Input - If the furnace control CPU switches from intermediate-

heat to a different medium range input (medium range input is an input rate between 52% and 71% of full rate, 46% and 71% of full rate on the 5T-060 model), the furnace control CPU will turn the blower ON or switch to the modulating heat airflow, and continue to maintain the inducer motor speed or change it further if required.

Switching from Intermediate-Heat to a High Range Input -

If the furnace control CPU switches from Intermediate-heat to a high range input (high range input is an input rate greater than or equal to 72% of full rate), the furnace control CPU will turn the blower ON or switch to the modulating heat airflow, and increase the inducer motor speed to the desired inducer motor RPM.

Switching fromLow Range Input to Maximum-Heat - If the

furnace control CPU switches from a low range input to maximum-heat, the furnace control CPU de-energize the PSR relay to close the NC contact and slowly increase the inducer motor speed until the medium pressure switch MPS closes. When the medium pressure switch MPS closes the inducer motor RPM is noted by the furnace control CPU. The RPM is used to evaluate vent system resistance. This evaluation is then used to determine the required RPM necessary to operate the inducer motor at maximum-heat. The blower motor BLWM will transition to maximum-heat airflow five seconds after the furnace control CPU switches from a low range input to maximum-heat. As the inducer RPM increases the high pressure switch HPS should close.

Switching from Medium Range Input to Maximum-Heat -

If the furnace control CPU switches from a medium range input to maximum-heat, the furnace control CPU will increase the inducer motor speed to the maximum-heat inducer motor RPM. The blower motor BLWM will transition to maximum-heat airflow five seconds after the furnace control CPU switches from a medium range input to maximum-heat. As the inducer RPM increases the high pressure switch HPS should close.

W1-and-W2 circuits always causes maximum-heat operation, regardless of the setting of the minimum-heat only switch.

The furnace will start up in either intermediate-, or maximum-heat. The furnace will operate in minimum-heat after starting and operating for 45 seconds at intermediate-heat before transitioning to minimum-heat.

The wall thermostat "calls for heat", closing the R to W1 circuit for minimum-heat or closing the R to W1-and-W2 circuits for maximum-heat. The furnace control performs a self-check, and verifies the low, medium, and high pressure switch contacts LPS, MPS, and HPS are open, then de-energizes the PSR relay to close the NC contact.

The start up and shut down functions and delays described above apply to the 2-stage minimum/maximum heating mode as well, except for switching from maximum- to minimum-heat.

1. Switching from Maximum- to Minimum-Heat - If the

thermostat R to W2 circuit opens, and the R to W1 circuit remains closed, the furnace control CPU will gradually decrease the inducer motor speed to the required intermediate-heat RPM. When the inducer motor IDM reduces pressure sufficiently, the high pressure switch HPS will open and the gas rate will be changed to intermediate-heat. The gas valve solenoid GV (pin PL17-5) will remain energized as long as the low pressure switch LPS remains closed. When the inducer motor speed gets within 15% of the required intermediate-heat RPM the furnace control CPU will start a 5 second blower airflow change delay. After the 5 second blower airflow change delay is completed the blower airflow will transition to minimum-heat airflow. At this point the furnace control CPU will energize the PSR relay to open the NC contact and slowly decrease the inducer motor speed to the required minimum-heat RPM. When the PSR relay is energized and the NC contact opens the furnace control CPU will reduce the gas rate to minimum-heat.

TWO-STAGE THERMOSTAT AND TWO-STAGE INTERMEDIATE/MAXIMUM HEATING

Note: In this mode the intermediate-heat only switch SW4-2 must

be ON to select the intermediate-heat only operation mode in response to closing the thermostat R to W1 circuit. Closing the thermostat R to W1-and-W2 circuits always causes maximum-heat operation, regardless of the setting of the intermediate-heat only switch.

8. Blower-Off Delay - When the thermostat is satisfied, the

R to W circuit is opened, de-energizing the gas valve GV, stopping gas flow to the burners, and de-energizing the humidifier terminal HUM. The inducer motor IDM will remain energized for a 15-second post-purge period. The blower motor BLWM and air cleaner terminal EAC-1 will remain energized at minimum-heat airflow or transition to minimum-heat airflow for 90, 120, 150, or 180 seconds (depending on selection at blower-OFF delay switches). The furnace control CPU is factory-set for a 120-second blower-OFF delay.

TWO-STAGE THERMOSTAT AND TWO-STAGE MINIMUM/MAXIMUM HEATING

Note: In this mode the minimum-heat only switch SW1-2 must be

ON to select the minimum-heat only operation mode in response to closing the thermostat R to W1 circuit. Closing the thermostat R to

The wall thermostat "calls for heat", closing the R to W1 circuit for intermediate-heat or closing the R to W1-and-W2 circuits for maximum-heat. The furnace control performs a self-check, and verifies the low, medium, and high pressure switch contacts LPS, MPS, and HPS are open, then de-energizes the PSR relay to close the NC contact.

The start up and shut down functions and delays described above apply to the 2-stage intermediate/maximum heating mode as well, except for switching from maximum- to intermediate-heat.

1. Switching from Maximum- to Intermediate-Heat – If the

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gets within 15% of the required intermediate-heat RPM the

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furnace control CPU will start a 5 second blower airflow change delay. After the 5 second blower airflow change delay is completed the blower airflow will transition to intermediateheat airflow.

COOLING MODE

The thermostat "calls for cooling".

1. Single-SpeedCooling

The thermostat closes the R to G-and-Y circuits. The R to Y circuit starts the outdoor unit, and the R to G-and-Y/Y2 circuits start the furnace blower motor BLWM on cooling airflow. Cooling airflow is based on the A/C selection shown in Table 1.

The electronic air cleaner terminal EAC-1 is energized with 115 vac when the blower motor BLWM is operating.

When the thermostat is satisfied, the R to G-and-Y circuits are opened. The outdoor unit will stop, and the furnace blower motor BLWM will continue operating at cooling airflow for an additional 90 seconds. Jumper Y/Y2 to DHUM to reduce the cooling off-delay to 5 seconds. (See Fig. 1.)

2. Two-StageThermostat and Two-SpeedCooling

The thermostat closes the R to G-and-Y1 circuits for lowcooling or closes the R to G-and-Y1-and-Y2 circuits for highcooling. The R to Y1 circuit starts the outdoor unit on lowcooling speed, and the R to G-and-Y1 circuit starts the furnace blower motor BLWM at low-cooling airflow which is the true on-board CF selection as shown in Table 1. The R to Y1-and-Y2 circuits start the outdoor unit on high-cooling speed, and the R to G-and-Y/Y2 circuits start the furnace blower motor BLWM at high-cooling airflow. High-cooling airflow is based on the A/C selection shown in Table 1.

The electronic air cleaner terminal EAC-1 is energized with 115 vac whenever the blower motor BLWM is operating.

When the thermostat is satisfied, the R to G-and-Y1 or R to G-and-Y1-and-Y2 circuits are opened. The outdoor unit stops, and the furnace blower BLWM and electronic air cleaner terminal EAC-1 will remain energized for an additional 90 seconds. Jumper Y1 to DHUM to reduce the cooling off-delay to 5 seconds. (See Fig. 1.)

DEHUMIDIFICATION MODE

The dehumidification output, D or DHUM on a Thermostat should be connected to the furnace control thermostat terminal DHUM. When there is a dehumidify demand, the DHUM input is activated, which means 24 vac signal is removed from the DHUM input terminal. In other words, the DHUM input logic is reversed. The DHUM input is turned ON when no dehumidify demand exists. Once 24 vac is detected by the furnace control on the DHUM input, dehumidification capability is activated. If the DHUM input is low for more than 48 hours, the furnace control reverts back to nondehumidification mode.

The cooling operation described above in the Cooling Mode section also applies to Dehumidification Mode. The exceptions are listed below:

1. Low Cooling - When the R to G-and-Y1 circuit is closed and

there is a demand for dehumidification, the furnace blower motor BLWM will drop the blower airflow to 86% of lowcooling airflow which is the true on-board CF selection as shown in Table 1.

2. High Cooling - When the R to G-and Y/Y2 circuit is closed

and there is a demand for dehumidification, the furnace blower motor BLWM will drop the blower airflow to 86% of highcooling airflow. High-cooling airflow is based on the A/C selection shown in Table 1.

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3. Cooling Off-Delay - When the “call for cooling” is satisfied

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and there is a demand for dehumidification, the cooling bloweroff delay is decreased from 90 seconds to 5 seconds.

SUPER-DEHUMIDIFY MODE

Super-Dehumidify mode can only be entered if the furnace control is in the Dehumidification mode and there is a demand for dehumidification. The cooling operation described in the Cooling Mode section above also applies to Super Dehumidify Mode. The exceptions are listed below:

1. Low Cooling – When the R to Y1 circuit is closed, R to G

circuit is open, and there is a demand for dehumidification, the furnace blower motor BLWM will drop the blower airflow to 65% of low-cooling airflow for a maximum of 10 minutes each cooling cycle or until the R to G circuit closes or the demand for dehumidification is satisfied. Low-cooling airflow is the true on-board CF selection as shown in Table 1.

2. High Cooling – When the R to Y/Y2 circuit is closed, R to G

circuit is open, and there is a demand for dehumidification, the furnace blower motor BLWM will drop the blower airflow to 65% of high-cooling airflow for a maximum of 10 minutes each cooling cycle or until the R to G circuit closes or the demand for dehumidification is satisfied. High-cooling airflow is based on the A/C selection shown in Table 1.

3. Cooling Off-Delay – When the “call for cooling” is satisfied

and there is a demand for dehumidification, the cooling bloweroff delay is decreased from 90 seconds to 5 seconds.

seconds at high-cooling airflow before transitioning back to continuous-blower airflow.

When the R to G circuit is opened, the blower motor BLWM will continue operating for an additional 5 seconds, if no other function requires blower motor BLWM operation.

HEATPUMP DEFROST

When installed with a heat pump, the furnace control automatically changes the timing sequence to avoid long blower off times during demand defrost cycles. Whenever W/W1 is energized along with Y1 or Y/Y2, the furnace control CPU will transition to or bring on the blower motor BLWM at cooling airflow, minimum-heat airflow, or the midrange airflow, whichever is lowest. The blower motor BLWM will remain on until the main burners ignite then shut OFF and remain OFF for 25 seconds before coming back on at modulating heat airflow. When the W/W1 input signal disappears, the furnace control begins a normal inducer post-purge period while changing the blower airflow. If Y/Y2 input is still energized the furnace control CPU will transition the blower motor BLWM airflow to cooling airflow. If Y/Y2 input signal disappears and the Y1 input is still energized the furnace control CPU will transition the blower motor BLWM to low-cooling airflow. If both the Y1 and Y/Y2 signals disappear at the same time, the blower motor BLWM will remain on at minimum-heat airflow for the selected blower-OFF delay period. At the end of the blower-OFF delay, the blower motor BLWM will shut OFF unless G is still energized, in which case the blower motor BLWM will operate at continuous blower airflow.

COMPONENT TEST

CONTINUOUS BLOWER MODE

When the R to G circuit is closed by the thermostat, the blower motor BLWM will operate at continuous blower airflow. Continuous blower airflow selection is initially based on the CF selection shown in Table 1. Factory default is shown in Table 1. Terminal EAC-1 is energized as long as the blower motor BLWM is energized.

During a call for heat, the furnace control CPU will transition the blower motor BLWM to continuous blower airflow, minimum-heat airflow, or the midrange airflow, whichever is lowest. The blower motor BLWM will remain ON until the main burners ignite then shut OFF and remain OFF for the blower-ON delay (45 seconds in intermediate-heat, and 25 seconds in maximum-heat), allowing the furnace heat exchangers to heat up more quickly, then restarts at the end of the blower-ON delay period at modulating or maximum-heat airflow respectively.

The blower motor BLWM will revert to continuous-blower airflow after the heating cycle is completed. When the thermostat satisfies, the furnace control CPU will drop the blower motor BLWM to minimum-heat airflow during the selected blower-OFF delay period before transitioning to continuous-blower airflow.

When the thermostat "calls for low-cooling", the blower motor BLWM will switch to low-cooling airflow. When the thermostat is satisfied, the blower motor BLWM will operate an additional 90 seconds at low-cooling airflow before transitioning back to continuous-blower airflow.

The furnace features a component test system to help diagnose a system problem in the case of a component failure. To initiate the component test procedure, ensure that there are no thermostat inputs to the control and all time delays have expired. Turn on setup switch SW1-6. (See Appendix A)

Note: The component test feature will not operate if the control is

receiving any thermostat signals or until all time delays have expired.

The component test sequence is as follows:

1. The furnace control CPU turns the inducer motor IDM ON at medium speed and keeps it ON through step 4.

2. The furnace control CPU will test communication with the modulating gas valve GV.

3. After waiting 15 seconds the furnace control CPU turns the hot surface igniter ON for 15 seconds, then OFF.

4. The furnace control CPU then turns the blower motor BLWM on at midrange airflow for 15 seconds, then OFF.

5. After shutting the blower motor OFF the furnace control CPU shuts the inducer motor IDM OFF.

Note: The EAC terminals are energized when the blower is

operating.

After the component test is completed, 1 or more status codes (Heartbeat, 2 + 5, 3 + 5, 4 + 1, or 4 + 2) will flash. See Service Label on control door or Service/Status Code Instructions for explanation of status codes.

When the thermostat "calls for high-cooling", the blower motor BLWM will switch to high cooling airflow. When the thermostat is satisfied, the blower motor BLWM will operate an additional 90

Note: To repeat component test, turn setup switch SW1-6 to OFF

and then back ON.

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SERVICE/STATUS CODE INSTRUCTIONS

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If status code recall is needed disconnect the “R” thermostat lead, reset power, and put setup switch “SW1-1” in the ON position. To clear the status code history put setup switch “SW1-1” in the ON position and jumper thermostat terminals “R”, “W/W1”, and “Y/Y2” simultaneously until the Heartbeat flashes.

LED CODE STATUS

CONTINUOUSOFF - Check 115 VAC at L1 and L2, 24 VAC at SEC-1 and SEC-2, and 24V fuse. HEARTBEAT - (bright-dim-bright-dim) Control has 24 VAC power. ON SOLID - The control is locked out and will auto reset after 1 hour. Lockout could be due to any of the following:

- Flame sense circuit failure.

- Gas valve relay stuck open.

- Software check error. Reset power to clear lockout. Replace control if status code repeats.

EACHOF THE FOLLOWING STATUS CODES IS A SINGLE OR TWO DIGIT NUMBERWITH THE FIRST NUMBERDETERMINED BY THE NUMBER OF SHORT FLASHES AND THE SECOND NUMBER AFTER THE (+) SIGN IS THE NUMBER OF LONG FLASHES.

2 PRESSURE SWITCH DID NOTOPEN – Check for:

- Obstructed pressure tubing.

- Pressure switch stuck closed.

3 LOW PRESSURESWITCHDID NOT CLOSE OR REOPENED – Indicates the low pressure switch input failed to close on a call for

heat, or opened during minimum-heat. If opens during blower on-delay period, blower will come on for the selected blower off-delay. If opens within 5 minutes after ignition the next heating cycle will be restricted to maximum-heat. Check for:

- Proper vent sizing.

- Air leak between vestibule and blower compartment.

- Restricted vent.

- Plugged condensate drain.

- Low inlet gas pressure (if LGPS used).

- Excessive wind. If problem persists turn setup switch “SW1-3” ON to boost inducer speed.

- Improper pressure switch wiring.

- Failed or “Out-of-Calibration” pressure switches.

- Water in vent piping, possible sagging pipe.

- Disconnected or obstructed pressure tubing.

4 LIMIT CIRCUITFAULT – Indicates the limit, or flame rollout is open or the furnace is operating in maximum-heat only mode due to 2

successive limit trips while operating at any rate less than or equal to 71% of maximum rate. Blower will run at intermediate heat airflow for 4 minutes or until open switch remakes whichever is longer. If open longer than 3 minutes, code changes to lockout #7. If open less than 3 minutes status code #4 continues to flash until blower shuts off. Flame rollout switch requires manual reset. Check for:

- Loose blower wheel.

- Defective switch or connections.

- Improper minimum- or maximum-heat gas input adjustment.

- Dirty filter or restricted duct system.

- Improper limit switch or no limit gasket.

5 ABNORMAL FLAME-PROVING SIGNAL – Flame is proved while gas valve is de-energized. Inducer will run until fault is cleared.

Check for:

- Leaky gas valve.

- Stuck-open gas valve.

6 IGNITION PROVINGFAILURE– Control will try three more times before lockout #6 + 1 occurs. If flame signal is lost during blower

on-delay period, blower will come on for the selected blower off-delay. Check for:

- Low inlet gas pressure.

- Control ground continuity.

- Gas valve defective or turned off.

- Defective Hot Surface Igniter.

- Manual valve shut off.

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

- Proper flame sense micro amps (.5 micro amps DC min., 4.0 – 6.0 nominal).

- Green/Yellow wire MUST be connected to furnace sheet metal.

- Inadequate flame carryover or rough ignition.

- Flame sensor must not be grounded.

7 LIMIT CIRCUIT LOCKOUT – Lockout occurs if the limit, or flame rollout switch is open longer than 3 minutes or 10 successive limit

trips occurred during maximum-heat. Control will auto reset after 3 hours. Refer to status code #4.

- 7 -

8 GAS HEATINGLOCKOUT – Control will NOT auto reset. Check for:

440 08 4001 00

- Stuck closed gas valve relay on control.

- Miswire or short to gas valve BLUE wire.

9 MEDIUM PRESSURE SWITCH, HIGH PRESSURE SWITCH, OR PSR RELAY DID NOT CLOSE OR REOPENED –

Indicates the medium or high pressure switch input failed to close on a call for intermediate- or maximum-heat, or opened during a heat cycle. PSR relay may be defective. Refer to status code #3.

10 POLARITY– Check for correct line voltage polarity. If units are twinned, check for proper low-voltage (24V) transformer phasing. 1 + 2 BLOWER ON AFTER POWER UP – (115 VAC or 24 VAC) – Normal operation. Blower runs for 90 seconds, if unit is powered up

during a call for heat (R-W/W1 closed) or (R-W/W1 opens) during the blower on-delay period.

1 + 5 BLOWERMOTOR LOCKOUT – Indicates the blower failed to reach 250 RPM or the blower failed to communicate within 30 seconds

after being turned ON in two successive heating cycles. Control will auto reset after 3 hours. Refer to status code #4 + 1.

2 + 5 MODEL SELECTION OR SETUP ERROR – If status code 2 + 5 only flashes 4 times on power-up the control is missing its model

plug PL4 and is defaulting to the model selection stored in memory. If status codes 2 + 5 flashes continuously it could indicate the following:

- Model plug PL4 is missing and there is no valid model stored in permanent memory. This will happen if you forget to install the model plug PL4 on a service replacement control.

- Thermostat call with setup switch “SW1-1” ON.

- Thermostat call with setup switch “SW1-6” ON.

- Setup switch “SW1-1” and “SW1-6” both ON together.

- Two different furnace models twinned.

- Service replacement control is incorrect. Need modulating board with software version V17 or later.

- See rating plate for model plug number and resistance values if code flashes continuously.

3 + 5 GAS VALVE FAULT– Indicates the modulating gas valve failed to respond to a command from the furnace control or power to the gas

valve electronics was interrupted. Check for:

- Intermittent RED, YELLOW, or ORANGE wire at gas valve or PL8 connections.

4 + 1 BLOWER MOTOR FAULT – Indicates the blower failed to reach 250 RPM or the blower failed to communicate within the prescribed

time limits. Thirty seconds after being turned ON or ten seconds during steady-state operation.

4 + 2 INDUCER MOTOR FAULT – Indicates the inducer has not started within 20 seconds after a call for heat, the inducer motor RPM is

outside its valid range of operation, or the inducer RPM signal was lost for 5 seconds during operation. Check for:

- Proper vent sizing.

- Restricted vent.

- Failed inducer motor.

- Improper motor wiring.

- Blockage in the tubing to the pressure switch assembly or blockage in the pressure tap at the collector box.

4 + 3 LOW OR MEDIUM PRESSURE SWITCH OPEN WHILE MEDIUM OR HIGH PRESSURE SWITCH IS CLOSED – Check

for:

- Low inlet gas pressure (if LGPS used).

- Plugged condensate drain.

- Improper pressure switch wiring.

- Water in vent piping, possible sagging pipe.

- Low or Medium pressure switch stuck open.

- Disconnected or obstructed pressure tubing.

6 + 1 IGNITION LOCKOUT – Control will auto reset after 3 hours. Refer to status code #6.

To initiate the component test sequence, shut “OFF” the room thermostat or disconnect the “R” thermostat lead. Reset power and then put setup switch “SW1-6” in the ON position to start the component test sequence. Once initiated the furnace control will turn the inducer ON at medium speed. The inducer motor will run for the entire test. The hot surface igniter and blower motor will be turned ON for 15 seconds each. When the blower is turned OFF the inducer will be turned OFF. When the component test is completed one or more of the following codes will flash.

LED CODE DESCRIPTION

HEARTBEAT Indicates the inducer motor, gas valve, & blower motor tested OK. Visual check of the hot surface igniter required. 2 + 5 SETUPERROR– Same as code 2 + 5 above. 3 + 5 GAS VALVEFAULT– Same as code 3 + 5 above. 4 + 1 BLOWERMOTORFAULT– Indicates blower motor failed test. Check blower, wiring, and furnace control. 4 + 2 INDUCER MOTOR FAULT– Indicates inducer motor failed test. Check inducer, wiring, and furnace control.

To repeat component test turn setup switch “SW1-6” OFF and then back ON. After component test is completed put setup switch “SW1-6” in the OFF position and reconnect the “R” thermostat lead.

COMPONENT TEST

- 8 -

START HERE - If a problem exists, the service technician should always begin

440 08 4001 00

troubleshooting here.

Special Note: All voltmeters are not the same - your voltage readings will vary. This applies to the entire content of this troubleshooting manual.

They are not absolute values. Correct 115-VAC VOLTAGE, CURRENT, and power MEASUREMENTS CANNOT BE TAKEN ON MODULATING FURNACES UNLESS USING A TRUE rms METER.

STEP ACTION YES NO GO TO

1. DO NOT REMOVE THE BLOWER DOOR! Record status of AMBER LED. See Service/Status Code Instructions.

Is AMBER LED status light ON SOLID, alternately flashing bright-dim-bright-dim like a heartbeat, or flashing ON and OFF?

2. Is AMBER LED status light ON SOLID? 3 4

3. Go to page number indicated in the Index for the section covering AMBER LED ON SOLID. INDEX

4. Is the AMBER LED status light alternately flashing bright-dim-bright-dim like a heartbeat? 7 5

5. Determine status code. The status code is a single or two digit number with the first number determined by the number of short flashes and the second number after the (+) sign is the number of long flashes.

6. Go to page number indicated in the Index for the section covering the status code. INDEX

7. Remove blower door and depress door switch. Use a piece of tape to hold it closed. To retrieve previous codes, disconnect the communication connector PL7 (if used) or the R thermostat lead (if used) from the furnace control board and wait for the blower to turn off if it is running. Put setup switch SW1-1 in the ON position and record the status codes listed in the status code history. The status codes will flash in the order of occurrence. Read status codes until the heartbeat flashes. After the heartbeat flashes several times the status codes will repeat.

8. Was there a previous status code other than the heartbeat?

2 19

9 10

Note: Status codes are erased after 72 hours or can be manually erased by putting setup

switch SW1-1 in the ON position and jumpering R, W/W1, and Y/Y2 simultaneously until the heartbeat flashes.

9. Go to page number indicated in the Index for the section covering the first previous status code.

10. Does the problem appear to be low cooling airflow? 11 12

11. Go to page number indicated in Index for the section covering IMPROPER COOLING AIRFLOW.

12. Set thermostat to call for heat and set the thermostat fan control to AUTO position if equipped.

13. Does the furnace respond to the call for heat? 14 28

14. Observe operation of furnace for 20 minutes or until AMBER LED status light starts blinking.

15. Does the AMBER LED status light blink ON/OFF slowly with short flashes or a combination of short and long flashes?

16. Is the temperature rise below the range specified on the rating plate when the unit is operating in minimum, and/or maximum heat?

Note:If the temperature rise is above the range specified on the rating plate refer to the Start-

Up and Adjustment section in the Installation, Start-Up, and Operating Instructions.

17. Go to page number indicated in Index for the section covering MINIMUM AND/OR MAXIMUM HEAT TEMPERATURE RISE TOO LOW (COLD BLOW).

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

19. Make sure power is being supplied to the furnace. 20

20. Check fuses, breakers, or manual disconnects to be sure they are correctly set. If not, reset them and go back to step 1.

21. Remove blower door and depress door switch. Use a piece of tape to hold switch closed. 22

22. Is 115-vac across L1 and L2? 24 23

23. Turn power off. Check continuity of power leads and door switch. If necessary repair power leads and/or replace door switch.

24. Is 24-vac across SEC-1 and SEC-2? 32 26

25. Replace the modulating furnace control. 18

5 16

17 18

INDEX

- 9 -

STEP ACTION YES NO GO TO

440 08 4001 00

26. Is 115-vac across the transformer leads? 27 25

27. Replace the transformer. 18

28. Is 24-vac across W/W1 and on the modulating furnace control?

You will not be able to check for voltage across W/W1 and COM-24V if the furnace is connected to a Communicating Wall Control at communication connector PL7. Go to step

29.

29. You have a defective thermostat, or a break in wiring between thermostat and furnace. Fix problem.

30. Disconnect all thermostat leads from the thermostat terminal block and jumper R to W/W1.

Does the furnace respond to the call for heat?

31. You have an incompatible thermostat. Do any of the following:

- Wire the thermostat C terminal to COM-24V.

- Isolate the W/W1 input with a relay.

- Install ballast resistor across W/W1 and COM-24V.

- Replace the thermostat with a compatible model.

32. Turn power off. Remove secondary voltage fuse from the modulating furnace control and check the continuity of the fuse.

33. Is the secondary voltage fuse open? 34 25

34. Go to page number indicated in Index for the section covering SECONDARY VOLTAGE FUSE IS OPEN.

30 29

31 25

INDEX

AMBER LED ON SOLID – Check to make sure the correct model plug PL4 is installed. The rating plate shows the correct model plug for this furnace. If the correct model plug is installed then the control is locked out and will auto reset after 1 hour. Lockout could be due to any of the following:

- Flame sense circuit failure.

- Gas valve relay stuck open.

- Software check error. Reset power to clear lockout. Replace control if status code repeats.

- 10 -

IMPROPER COOLING AIR FLOW - Generally, this indicates the Y/Y2 thermostat lead is not

440 08 4001 00

properly connected. If a Communicating Wall Control is connected to communication connector PL7 then the wrong size outdoor unit could be configured in the Communicating Wall Control.

STEP ACTION YES NO GO TO

1. Remove blower door and depress door switch. Use a piece of tape to hold switch closed. 27

2. Set thermostat to call for cooling. If thermostat does not have G connection jumper across thermostat terminals R and G.

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

4. Do you have 24-vac across Y/Y2 and COM-24V on the modulating furnace control? 8 5

5. You have a defective thermostat, or a break in the wiring between the thermostat and the furnace, or the Y/Y2 thermostat terminal is not wired to the thermostat.

6. Fix the problem. 7

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

8. Are the air conditioning airflow select switches A/C set to the proper airflow as required by the condensing unit? Typical airflow is based on 350 CFM/TON (See Table 2.)

9. Set the air conditioning airflow select switches A/C to the proper airflow as required by the condensing unit. (See Table 2.)

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

11. Does the blower motor turn off in 5 seconds when the G thermostat lead is disconnected?

Note:When using a humidity sensing thermostat the blower may change airflow when the G

thermostat lead is disconnected and a call to dehumidify is active.

12. Replace the modulating furnace control. 7

13. Reconnect the G thermostat lead or jumper and observe operation of furnace in cooling mode for 10 minutes.

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

15. - Check outdoor unit for correct suction pressure and verify charge.

- Check filter(s) and ductwork for restrictions.

- Check furnace coil.

16. Does the AMBER LED abruptly shut off as the blower comes up to speed? 17 24

17. Do you have less than 17-vac between R and COM-24V on the modulating furnace control? 18 24

18. Do you have less than 90-vac between L1 and L2 on the modulating furnace control? 19 20

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

20. Disconnect the R thermostat lead. 21

21. Do you have less than 17-vac between R and COM-24V on the modulating furnace control? 22 23

22. Replace transformer. 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 ft. For wire lengths over 100 ft, use AWG No. 16 wire.

24. Is Status Code 4 + 1 flashing? 25 26

25. Go to the page number indicated in the Index for Status Code 4 + 1. INDEX

26. - Check outdoor unit for correct suction pressure and verify charge.

- Check furnace coil.

27. Is a Communicating Wall Control connected to communication connector PL7? 28 2

28. The wrong size outdoor unit may have been selected in the Communicating Wall Control. You will need to set the proper size of the outdoor unit in the Communicating Wall Control. If set properly then the Communicating Wall Control may be reducing the airflow for dehumidification.

10 9

12 13

INDEX

- 11 -

Table2 – CoolingTonnage vs. Airflow (CFM)

440 08 4001 00

AIR CONDITIONINGTONS

(12,000BTU/HR)

1-1/2

2-1/2

3-1/2

4 5 6

AIRFLOW

(CFM)

3.5T-060&

3.5T-080MODEL

5T-060MODEL 5T-080 MODEL 100 & 120

525 X X 700 X X X X

875 X X X X 1050 X X X X 1225 X X X X 1400 X X X 1750 X X X 2100 X

AIR CONDITIONING (A/C) OR CONTINUOUS-FAN (CF)

BASED ON 350 CFM/TON (SETUP SWITCH SW1-5 OFF, SW4-3 OFF)

MODEL

SIZE

3.5T-60, -80

5T-80

100

BASED ON 400 CFM/TON (SETUP SWITCH SW1-5 ON, SW4-3 OFF)

MODEL

SIZE

AIRFLOW SELECTION CHART

SETUP SWITCH SW2 OR SW3 POSITIONS

525

700

875

1050

1225

1400

DEF.

DEF.5T-60

DEF.

5252700 875 1050 1225 1400 1750

700

875 1050

7002875 1050

700 87521050 1225 1400 175012100DEF.120

SETUP SWITCH SW2 OR SW3 POSITIONS

1225

1750

1225

1750

2100

MODEL

6002800 1000 120011400 1400 1400DEF.3.5T-60, -80

6002800 1000 1200 1400 1600 2000

DEF.5T-60

5T-80

100

80021000 1200

DEF.

80021000 1200

DEF.

1400

1600

2000

800 100021200 1400 1600 200012100DEF.120

BASED ON 325 CFM/TON (SETUP SWITCH SW1-5 OFF, SW4-3 ON)

SETUP SWITCH SW2 OR SW3 POSITIONS

MODEL

SIZE

488

651

814

976

1139

1302

1139

1627

3.5T-60, -80

5T-80

100

DEF.

DEF.5T-60

DEF.

4882651 814 976 1139 1302 1627

651

814 976

6512814 976

1139

651 8142976 1139 1302 162711953DEF.120

BASED ON 370 CFM/TON (SETUP SWITCH SW1-5 ON, SW4-3 ON)

SETUP SWITCH SW2 OR SW3 POSITIONS

MODEL

SIZE

558

744

930

1116

1302

1488

1302

1860

3.5T-60, -80

5T-80

100

DEF.

DEF.5T-60

DEF.

5582744 930 1116 1302 1488 1860

744

930 1116

7442930 1116

1302

744 93021116 1302 1488 186012100DEF.120

1. DEFAULT A/C AIRFLOW WHEN A/C SWITCHES ARE IN OFF POSITION

2. DEFAULT CONT. FAN AIRFLOW WHEN CF SWITCHES ARE IN OFF POSITION

3. SWITCH POSITIONS ARE ALSO SHOWN ON FURNACE WIRING DIAGRAM

2000

2100

1139

1627

1953

1302

1860

2100

- 12 -

MINIMUM AND/OR MAXIMUM HEAT TEMPERATURE RISE TOO LOW - Generally, this

440 08 4001 00

indicates the furnace is extremely underfired.

STEP ACTION YES NO GO TO

1. Remove the blower door. Disconnect the communication connector PL7 (if used) or the R thermostat lead (if used) from the furnace control board. If setup switch SW4-2 is ON then turn it OFF.

2. Depress the door switch. Use piece of tape to hold it closed. 3

3. Put setup switch SW1-2 into the ON position. 4

4. Jumper R, W/W1, and W2 thermostat terminals. 5

5. Once the blower motor turns ON and the furnace is running in maximum heat, clock the maximum heat gas rate. On propane installations check the manifold pressure.

6. Is the maximum heat rate within 2% of that specified on the rating plate? 9 7

7. Ensure the gas inlet pressure and burner orifices are correct. Reference the Installation, StartUp, and Operating Instructions. Then adjust maximum heat on the gas valve to the proper manifold pressure. If maximum heat cannot be adjusted to the proper manifold pressure, replace the gas valve GV.

Note: The modulating furnace manifold pressure is set at two points. The first point is

maximum heat. The second point is minimum heat. Both adjustments are independent and are done with the same rotary adjustment switch on the modulating gas valve. When adjusting do not apply excessive force as you may damage the rotary adjustment switch. To adjust, slowly turn the rotary adjustment switch counterclockwise to decrease manifold pressure or clockwise to increase manifold pressure. Turn the rotary adjustment switch one click per second until you obtain the desired manifold pressure. If you turn the rotary adjustment switch too quickly the manifold pressure will not change.

8. Fix problem. 11

9. Check maximum heat temperature rise and external static pressure with blower door in place. Temperature rise should be mid range or higher than midpoint of range stated on furnace rating plate. External static pressure in maximum heat should be less then .7 in.w.c. If return temperature is below 60 deg. F condensation may form on heat exchangers. If left uncorrected failure will result.

10. Remove the jumper from the R and W2 thermostat terminals. When the furnace is running in minimum heat, clock the minimum heat gas rate. On propane installations check the manifold pressure.

11. Go to the page number indicated in Index for the CLEANUP AND STARTUP INSTRUCTIONS.

12. Is the minimum heat rate within 2% of that specified on the rating plate? 14 13

13. Ensure the gas inlet pressure and burner orifices are correct. Reference the Installation, StartUp, and Operating Instructions. Then adjust minimum heat on the gas valve to the proper manifold pressure. If minimum heat cannot be adjusted to the proper manifold pressure, replace the gas valve GV.

INDEX

Note: The modulating furnace manifold pressure is set at two points. The first point is

14. Is outdoor condensing unit operating during heating cycle? 8 15

15. Check minimum heat temperature rise and external static pressure with blower door in place. Temperature rise should be mid range or higher than midpoint of range stated on furnace rating plate. External static pressure in minimum heat should be less then .25 in.w.c. If return temperature is below 60 deg. F condensation may form on heat exchangers. If left uncorrected failure will result.

16. Check return air ducts in unheated spaces for leaks. 11

- 13 -

SECONDARY VOLTAGE FUSE IS OPEN

440 08 4001 00

STEP ACTION YES NO GO TO

1. Turn power off and remove the blower door. 2

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

3. Replace modulating furnace control. 4

4. Replace secondary voltage fuse if necessary then go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS.

5. Disconnect the communication connector PL7 (if used), or all thermostat leads (if used) from the modulating furnace control (including all wires connected to the HUM terminal) and replace secondary voltage fuse.

6. Turn power on and depress door switch. Use a piece of tape to hold switch closed. 7

7. Does the AMBER LED alternately flash bright-dim-bright-dim like a heartbeat? 12 8

8. Turn power off and disconnect PL1 from modulating furnace control. 9

9. Do you have continuity between either RED wire connected to the limit circuit and chassis ground?

10. You have a short circuit in the limit switch circuit. This includes limit switch LS, and both flame roll-out switches FRS.

11. Fix problem. 4

12. Disconnect the pressure tube from the collector box and jumper R and W/W1 thermostat terminals.

13. Does the AMBER LED turn off when W/W1 is energized? 14 20

14. Turn power off and disconnect PL1 from modulating furnace control. 15

15. Do you have continuity between the YELLOW wire connected to the low pressure switch LPS and chassis ground?

16. You have a short circuit in the YELLOW wire to the low pressure switch LPS. 11

17. Does the AMBER LED turn off when the HUM terminal is energized?

10 41

16 39

3 18

INDEX

Note: On the modulating furnace control the HUM terminal is energized when the blower

turns ON.

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

19. Jumper R, W/W1, and W2 thermostat terminals. 44

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

21. Reconnect the pressure tube from the pressure switch assembly back to the collector box. 22

22. Jumper R and W/W1 thermostat terminals. 23

23. Does the AMBER LED turn off before the hot surface igniter HSI is energized? 24 33

24. Turn power off and disconnect PL1 from modulating furnace control. 25

25. Do you have continuity between the ORANGE wire connected to the low pressure switch LPS and chassis ground?

26. The ORANGE wire from low pressure switch LPS is shorting to ground. Replace or repair it.

27. Do you have continuity between the VIOLET wire connected to the medium pressure switch MPS and chassis ground?

28. The VIOLET wire from medium pressure switch MPS is shorting to ground. Replace or repair it.

29. Disconnect jumper wire across R and W/W1 thermostat terminals, reconnect PL1 to the modulating furnace control, disconnect PL17 from modulating gas valve, and replace secondary voltage fuse.

30. Turn power on and depress door switch. Use a piece of tape to hold switch closed. 31

31. Jumper R and W/W1 thermostat terminals. 32

32. Does status code 3 + 5 flash? 60 3

33. Does the AMBER LED turn off when the gas valve GV is energized? 34 17

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

35. Put gas valve manual ON/OFF switch in the OFF position and jumper R and W/W1 thermostat terminals.

26 27

28 29

- 14 -

STEP ACTION YES NO GO TO

440 08 4001 00

36. Does status code 6 flash? If not, the AMBER LED should turn off when BLUE wire is

60 37

energized.

37. Turn power off and disconnect PL1 from modulating furnace control. 38

38. Do you have continuity between the BLUE wire and chassis ground? 59 3

39. Do you have continuity between the GRAY wire connected to both the medium and high

40 3

pressure switches and chassis ground?

40. You have a short circuit in the GRAY wire to the medium and high pressure switches. 11

41. Disconnect PL8 from modulating furnace control. 42

42. Do you have continuity between RED wire on PL8 and chassis ground?

61 3

Note: The terminals can be permanently damaged if the continuity probe is jammed into the

terminal end of the connector. Use caution when checking continuity.

43. The RED wire to the modulating gas valve is shorting to ground. Replace or repair it. 11

44. Does the AMBER LED turn off when the high pressure switch HPS is energized? 45 48

45. Turn power off and disconnect PL8 from modulating furnace control. 46

46. Do you have continuity between the BROWN wire on PL8 and chassis ground?

47 3

Note: The terminals can be permanently damaged if the continuity probe is jammed into the

terminal end of the connector. Use caution when checking continuity.

47. The BROWN wire to the high pressure switch HPS is shorting to ground. Replace or repair

it.

48. Disconnect jumper wire across R, W/W1, and W2 thermostat terminals and wait until blower

stops.

49. Jumper R, G, and Y/Y2 thermostat terminals. 50

50. Does the AMBER LED turn off when G and Y/Y2 are energized? 3 51

51. Reconnect communication connector PL7 (if used) or all thermostat leads (if used) to the

52 modulating furnace control. Do not reconnect the humidifier lead to HUM terminal. Operate the furnace in heating and cooling mode from thermostat.

52. Does the AMBER LED turn off during the heating cycle? 53 54

53. You have a defective thermostat or a short circuit in the wiring between thermostat and

11 furnace. If the furnace is twinned, also check the twinning kit relay TKR.

54. Does the AMBER LED turn off during the cooling cycle? 55 56

55. You have a defective thermostat or a short circuit in the wiring between thermostat and

11 outdoor unit, or a short circuit in the outdoor unit contactor or reversing valve(heat pump only).

56. Does the problem usually occur in cooling mode? 57 58

57. Check outdoor unit contactor. Failure to pull in can cause excessive current draw on low-

11 voltage circuit. This can be an intermittent problem.

58. Reconnect humidifier and check for excessive current draw when the blower turns ON. If

11 current draw is excessive check wiring to humidifier solenoid, diode bridge(if used), and humidifier solenoid.

59. The BLUE wire to gas valve GV is shorting to ground. Replace or repair it. 11

60. Replace gas valve GV. 4

61. Disconnect PL17 from modulating gas valve. 62

62. Do you have continuity between RED wire on PL8 and chassis ground?

43 60

Note: The terminals can be permanently damaged if the continuity probe is jammed into the

terminal end of the connector. Use caution when checking continuity.

- 15 -

+ 33 hidden pages

ICP 9MAC/E Troubleshooting Manual

Specifications and Main Features

Frequently Asked Questions

User Manual