ICP 9MAC/E series Troubleshooting Manual
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ICP 9MAC/E series Troubleshooting Manual

ICP 9MAC/E series Troubleshooting Manual

Variable speed, modulating electronic condensing four-way multipoise gas furnace
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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

TROUBLESHOOTING GUIDE

INDEX
Four-Way Multipoise Gas Furnace
*9MAC
APPENDIX E - Quick Reference Information..................................... 45
APPENDIX F - Furnace Staging Algorithm ........................................ 46
PAGE
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.
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.
suggestions which will result in enhanced installation, reliability, or
operation.
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.
1-
Replaces: New
-
Variable Speed, Modulating
Electronic Condensing
SAFETY CONSIDERATIONS
NOTE is used to highlight
INSTRUCTIONS
440 08 4001 00
.
!
DANGER
Form: ICP Eng
3-12

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  • Page 1: Troubleshooting Guide

    APPENDIX C - Pressure Check Diagram ..........42 which will lead you to one of the sections as listed in the Index. APPENDIX D - Static Pressure Reading Location Diagrams....43 Replaces: New Form: ICP Eng 440 08 4001 00 3-12...

  • Page 2: Sequence Of Operation

    You should ALWAYS begin in the START HERE section (see to the step indicated in the YES column. If the answer is NO, go to Index for page number) which will guide you to the appropriate the step indicated in the NO column. section where a minimal number of steps will be used to correct the problem.

  • Page 3: Single-Stage Thermostat And Modulating Heating (Adaptive Mode)

    Thermostat section, EXCEPT that the communicating control will Note: The heat cycle can start in either intermediate- or maximum- send modulating rate command signals through the communication heat. If a maximum-heat cycle is initiated, the furnace control CPU bus rather than energizing the 24-v thermostat terminals. will continue to increase the inducer motor speed after the medium pressure switch MPS closes.

  • Page 4: Two-Stage Thermostat And Two-Stage Minimum/Maximum Heating

    range input (low range input is an input rate less than or equal W1-and-W2 circuits always causes maximum-heat operation, to 51% of full rate, 45% of full rate on the 5T-060 model), the regardless of the setting of the minimum-heat only switch. furnace control will turn the blower ON or switch to the modulating heat airflow, energize the PSR relay to open the NC The furnace will start up in either intermediate-, or maximum-heat.

  • Page 5: Cooling Mode

    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 intermediate- heat airflow. COOLING MODE The thermostat "calls for cooling".

  • Page 6: Super-Dehumidify Mode

    Cooling Off-Delay - When the “call for cooling” is satisfied seconds at high-cooling airflow before transitioning back to continuous-blower airflow. and there is a demand for dehumidification, the cooling blower- off delay is decreased from 90 seconds to 5 seconds. When the R to G circuit is opened, the blower motor BLWM will continue operating for an additional 5 seconds, if no other function SUPER-DEHUMIDIFY MODE...

  • Page 7: Service/Status Code Instructions

    SERVICE/STATUS CODE INSTRUCTIONS 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.

  • Page 8: Component Test

    GAS HEATING LOCKOUT – Control will NOT auto reset. Check for: Stuck closed gas valve relay on control. Miswire or short to gas valve BLUE wire. 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.

  • Page 9: Start Here

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

  • Page 10: Amber Led On Solid

    STEP ACTION GO TO Is 115-vac across the transformer leads? Replace the transformer. 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 C -24V if the furnace is connected to a Communicating Wall Control at communication connector PL7.

  • Page 11: Improper Cooling Air Flow

    IMPROPER COOLING AIR FLOW - Generally, this indicates the Y/Y2 thermostat lead is not 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 GO TO...
  • Page 12 Table 2 – Cooling Tonnage vs. Airflow (CFM) AIR CONDITIONING TONS AIRFLOW 3.5T-060 & 5T-060 MODEL 5T-080 MODEL 100 & 120 (12,000 BTU/HR) (CFM) 3.5T-080 MODEL MODEL 1-1/2 2-1/2 1050 1225 3-1/2 1400 1750 2100 AIR CONDITIONING (A/C) OR CONTINUOUS-FAN (CF) AIRFLOW SELECTION CHART BASED ON 350 CFM/TON (SETUP SWITCH SW1-5 OFF, SW4-3 OFF) SETUP SWITCH SW2 OR SW3 POSITIONS...

  • Page 13: Minimum And/Or Maximum Heat Temperature Rise Too Low

    MINIMUM AND/OR MAXIMUM HEAT TEMPERATURE RISE TOO LOW - Generally, this indicates the furnace is extremely underfired. STEP ACTION GO TO 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.
  • Page 14 SECONDARY VOLTAGE FUSE IS OPEN STEP ACTION GO TO Turn power off and remove the blower door. Is secondary voltage fuse blown? Check continuity to make sure. Replace modulating furnace control. Replace secondary voltage fuse if necessary then go to page number indicated in Index for INDEX CLEANUP AND START-UP INSTRUCTIONS.
  • Page 15 STEP ACTION GO TO Does status code 6 flash? If not, the AMBER LED should turn off when BLUE wire is energized. Turn power off and disconnect PL1 from modulating furnace control. Do you have continuity between the BLUE wire and chassis ground? Do you have continuity between the GRAY wire connected to both the medium and high pressure switches and chassis ground? You have a short circuit in the GRAY wire to the medium and high pressure switches.

  • Page 16: Status Code 2 - Pressure Switch Did Not Open

    Status Code 2 PRESSURE SWITCH DID NOT OPEN - This status code indicates the low, medium, or high pressure switch LPS, MPS, or HPS is made when a call for heat is initiated. The modulating furnace control will flash status code 2 until the switch opens, then cycle begins.

  • Page 17: Status Code 3 - Low Pressure Switch Did Not Close Or Reopened

    Status Code 3 LOW PRESSURE SWITCH DID NOT CLOSE OR REOPENED - This status code can occur as a result of the low pressure switch LPS not making or the low gas pressure switch LGPS opening. Regardless of which switch is open, the modulating furnace control will operate under the scenarios shown below.
  • Page 18 STEP ACTION GO TO You have excessive restriction in combustion-air or vent pipe. Also check for proper vent sizing for installation. Continue to observe furnace operation for 20 minutes or until status code starts flashing. Does status code 3 flash? Does a different status code flash? Turn power off and disconnect jumper wire across R and W/W1 thermostat terminals.

  • Page 19: Status Code 4 - Limit Circuit Fault

    Status Code 4 LIMIT CIRCUIT FAULT - This status code indicates the limit, flame rollout switch is open, or the furnace is operating in maximum-heat only mode due to 2 successive limit trips while operating at any rate < 71% of maximum rate. Blower will run for 4 minutes at intermediate heat airflow or until the open switch remakes whichever is longer.
  • Page 20 STEP ACTION GO TO Remove tape from door switch, turn power off at main disconnect, and remove jumper across R and W/W1. Is the blower wheel firmly mounted on motor shaft? Does the model plug PL4 match the part number specified on the Rating Plate? Replace model plug.

  • Page 21: Status Code 5 - Abnormal Flame-Proving Signal

    Status Code 5 ABNORMAL FLAME-PROVING SIGNAL - This status code indicates the flame signal was sensed while gas valve GV was de- energized. The inducer will run until the fault is cleared. STEP ACTION GO TO Turn off gas to the furnace by shutting off the external manual shut-off valve. Does status code 5 stop flashing? Replace the gas valve.
  • Page 22 STEP ACTION GO TO Do the main burners stay on longer than a few seconds? Turn off the power and disconnect the jumpers across the R, W/W1, and W2 thermostat terminals. Connect a DC microampmeter in series with the flame sensor wire. Turn power on and jumper R, W/W1, and W2 thermostat terminals.

  • Page 23: Status Code 7 - Limit Circuit Lockout

    Status Code 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. The modulating furnace control will auto-reset in 3 hours. Flame roll- out switch(es) FRS require manual-reset.

  • Page 24: Status Code 8 - Gas Heating Lockout

    Status Code 8 GAS HEATING LOCKOUT - This status code indicates the gas valve relay GVR on the modulating furnace control is stuck closed or there is a miswire/short to gas valve BLUE wire. The modulating furnace control will NOT auto-reset. STEP ACTION GO TO...
  • Page 25 MEDIUM TO LOW RANGE INPUT TRANSITION – When transitioning to a low range input the medium pressure switch MPS should open when the PSR relay is energized to open the NC contact. However if the PSR relay contact remains closed and the medium pressure switch MPS is made the modulating furnace control begins flashing status code 9and continues to operate at the desired low range input.
  • Page 26 STEP ACTION GO TO Did the medium pressure switch MPS make, then break several times at start of cycle before faulting out? The problem is either a sag in vent pipe or a clogged drain trap or line. Also check for improperly plumbed drain tubing within furnace.

  • Page 27: Status Code 10 - Polarity

    STEP ACTION GO TO Do you have continuity between the GRAY wire on the medium pressure switch MPS and the YELLOW wire on the low pressure switch? The GRAY wire is shorting to the YELLOW or ORANGE wire that goes to the low pressure switch LPS.

  • Page 28: Status Code 1 + 2 - Blower On After Power Up

    Status Code 1 + 2 BLOWER ON AFTER POWER UP - Blower will run for 90 seconds when furnace power is interrupted and later restored during a call for heat (R-W/W1 closed) or if the call for heat is interrupted (R-W/W1 opens) during the blower on-delay period. If this status code repeats every couple of minutes it is probably caused by a direct short in the pressure switch circuits, gas valve GV, wiring to gas valve GV, or humidifier coil.

  • Page 29: Status Code 2 + 5 - Model Selection Or Setup Error

    Status Code 2 + 5 MODEL SELECTION OR SETUP ERROR – If status code 2 + 5 only flashes 4 times on power-up the modulating furnace control is missing its model plug (PL4) and is defaulting to the model selection stored in memory. If status code 2 + 5 flashes continuously it could indicate any of the following: Model plug (PL4) is missing and there is no valid model stored in permanent memory.
  • Page 30 Status Code 3 + 5 GAS VALVE FAULT - This status code indicates that the modulating gas valve failed to respond to a command from the modulating furnace control or power to the gas valve electronics was interrupted. On every cycle after the medium pressure switch MPS makes the modulating furnace control sends a PWM (pulse width modulation) command to the gas valve GV for a duration of 1 second.
  • Page 31 STEP ACTION GO TO Do you have continuity between PL8-2 and PL17-2? Note: The terminals in PL8 can be permanently damaged if the voltmeter probe is jammed into the terminal end of the connector. Use caution when checking. You have an open wire or a bad terminal on the YELLOW wire between connector PL8 and PL17.

  • Page 32: Status Code 4 + 1 - Blower Motor Fault

    Status Code 4 + 1 BLOWER MOTOR FAULT - This status code indicates the blower failed to reach 250 RPM or the blower failed to communicate to the modulating furnace control within 30 seconds after being turned ON or within 10 seconds during steady-state operation.
  • Page 33 STEP ACTION GO TO Check the blower motor serial output signal. To do this disconnect PL3 from the furnace control and connect a DC voltmeter across terminals PL3-4 (+) and PL3-2 (-) on the modulating furnace control. The voltage should be near 0-vdc but it will fluctuate briefly several times a second.

  • Page 34: Status Code 4 + 2 - Inducer Motor Fault

    STEP ACTION GO TO When blower control module is completely detached from blower motor, verify with standard ohmmeter that the resistance from each motor lead in motor plug to unpainted motor end plate is greater than 100k ohms. Then verify motor windings are not shorted or open by measuring resistance between each combination of pins in motor plug (there are three different combinations, pin 1-2, pin 2-3, and pin 1-3).
  • Page 35 STEP ACTION GO TO Reconnect PL16 to the inducer motor and put setup switch SW1-6 in the OFF position. Does inducer wheel turn freely? Replace the inducer motor control (if you have a 2 piece design) or the inducer motor assembly.

  • Page 36: Status Code 4 + 3 - Low Or Medium Pressure Switch Open While Medium Or High Pressure Switch Is Closed

    STEP ACTION GO TO Does a different status code flash? Is there any frost build-up on combustion-air inlet? The problem is caused by reversed vent and combustion-air pipes or some other moist air entering combustion-air pipe. You have excessive restriction in combustion-air or vent pipe. Also check for proper vent sizing for installation.

  • Page 37: Cleanup And Start-Up Instructions

    STEP ACTION GO TO Is 24-vac across GRAY wire on the medium pressure switch MPS and C -24V on modulating furnace control? You have an open wire or bad terminal on the GRAY wire from the high pressure switch HPS to the medium pressure switch MPS. Repair it or replace the harness. Is 24-vac across VIOLET wire on the medium pressure switch MPS and C -24V on modulating furnace control?
  • Page 38 APPENDIX A BOARD LAYOUT AND WIRING SCHEMATICS COMMUNICATION CONTINUOUS FAN OUTDOOR SW4 SETUP CONNECTOR (CF) AIRFLOW AIR TEMP SWITCHES SETUP SWITCHES CONNECTOR MODEL PLUG CONNECTOR SW1 SETUP SWITCHES AND BLOWER OFF- DELAY AIR CONDITIONING (A/C) AIRFLOW SETUP SWITCHES HUMIDIFIER TERMINAL (24-VAC 0.5 AMP MAX.
  • Page 39 Fig. 2 – Wiring Schematic 440 08 4001 00 - 39 -...

  • Page 40: Appendix B - Ecm Blower Motor Description & Operation

    APPENDIX B ECM BLOWER MOTOR DESCRIPTION & OPERATION The Regal-Beloit Electronically Commutated Motor (ECM) shown in figure 3 is the newest generation of variable speed blower motors. This motor has all of the capabilities of the previous ECM blower motor but has internal memory storage which provides operational information to the manufacturer when the motor is returned.
  • Page 41 Figure 3 – ECM Blower Motor 440 08 4001 00 - 41 -...

  • Page 42: Appendix C - Pressure Check Diagram

    APPENDIX C PRESSURE CHECK DIAGRAM PRESSURE SWITCH MAKE/BREAK POINTS HIGH PRESSURE SWITCH MEDIUM PRESSURE SWITCH LOW PRESSURE SWITCH UNIT SIZE (BTUH) Make Point Break Point Make Point Break Point Make Point Break Point 1.05 in. wc +/- 0.70 in. wc +/- 0.47 in.

  • Page 43: Appendix D - Static Pressure Reading Location Diagrams

    APPENDIX D STATIC PRESSURE READING LOCATION DIAGRAMS Figure 5 – Upflow Total Static Pressure Reading Locations Figure 6 – Downflow Total Static Pressure Reading Locations 440 08 4001 00 - 43 -...
  • Page 44 Figure 7 – Horizontal Right Total Static Pressure Reading Locations Tools Needed: Pitot Tube Incline Manometer/Magnahelic Example 1: Return ESP after Filter 0.20 in.w.c. Supply ESP before Coil 0.40 in.w.c. ------------------------------------------------------ Total ESP 0.60 in.w.c. Example 2: Return ESP before Filter 0.10 in.w.c.

  • Page 45: Appendix E - Quick Reference Information

    APPENDIX E QUICK REFERENCE INFORMATION PRESSURE SWITCH MAKE/BREAK POINTS HIGH PRESSURE SWITCH MEDIUM PRESSURE SWITCH LOW PRESSURE SWITCH UNIT SIZE (BTUH) Make Point Break Point Make Point Break Point Make Point Break Point 1.05 in. wc +/- 0.70 in. wc +/- 0.47 in.

  • Page 46: Appendix F - Furnace Staging Algorithm

    APPENDIX F FURNACE STAGING ALGORITHM On initial thermostat call for heat after power-up, furnace staging algorithm will provide 45 seconds of intermediate heat followed by 19 minutes of minimum heat provided setup switches SW1-2 and SW4-2 are off. If call for heat still exists after operating for 45 seconds in intermediate heat and 19 minutes in minimum heat, the furnace will switch to maximum heat until the thermostat is satisfied.
  • Page 47 Using recorded Modulating rate (MOD%), time of operation at the Modulating rate (MODT), and Maximum Heat (MAXT) calculate the Heat Load Thermostat is satisfied. (HLR) using: HLR = (MOD% x MODT) + 65 + (100 x MAXT) Unit will start the next cycle in Intermediate Heat for 45 seconds The Modulating rate followed by 19 minutes of operation...
  • Page 48 - 48 - Replaces: New Form: ICP Eng 440 08 4001 00 3-12...

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