ICP 9MAC/E series Troubleshooting manual

Manual is about: Variable Speed, Modulating Electronic Condensing Four-Way Multipoise Gas Furnace

Summary of 9MAC/E series

  • Page 1

    - 1- replaces: new form: icp eng 3-12 variable speed, modulating electronic condensing four-way multipoise gas furnace *9mac ( troubleshooting guide index page safety considerations.............................................................................. 1 instructions ............................

  • Page 2

    - 2 - you should always begin in the start here section (see index for page number) which will guide you to the appropriate 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 th...

  • Page 3

    - 3 - thermostat section, except that the communicating control will send modulating rate command signals through the communication bus rather than energizing the 24-v thermostat terminals. Single-stage thermostat and modulating heating (adaptive mode) note : minimum-heat only switch sw1-2 selects t...

  • Page 4

    - 4 - range input (low range input is an input rate less than or equal 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 moto...

  • Page 5

    - 5 - 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 ...

  • Page 6

    - 6 - 3. Cooling off-delay - when the “call for cooling” is satisfied and there is a demand for dehumidification, the cooling blower- off 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...

  • Page 7

    - 7 - 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...

  • Page 8

    - 8 - 8 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. 9 medium pressure switch, high pressure switch, or psr relay did not close or reopened – indicates the medium or high pressure switch input fail...

  • Page 9

    - 9 - 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 ...

  • Page 10

    - 10 - step action yes no go to 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 c om -24v if the furnace is connected to a communicating wall ...

  • Page 11

    - 11 - 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 yes no go t...

  • Page 12

    - 12 - table 2 – cooling tonnage vs. Airflow (cfm) air conditioning tons (12,000 btu/hr) airflow (cfm) 3.5t-060 & 3.5t-080 model 5t-060 model 5t-080 model 100 & 120 model 1-1/2 525 x x 2 700 x x x x 2-1/2 875 x x x x 3 1050 x x x x 3-1/2 1225 x x x x 4 1400 x x x 5 1750 x x x 6 2100 x air conditioni...

  • Page 13

    - 13 - minimum and/or maximum heat temperature rise too low - generally, this 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 ...

  • Page 14

    - 14 - secondary voltage fuse is open 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 indicat...

  • Page 15

    - 15 - step action yes no go to 36. Does status code 6 flash? If not, the amber led should turn off when blue wire is energized. 60 37 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 c...

  • Page 16: Status Code 2

    - 16 - 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. Step action yes no go...

  • Page 17: Status Code 3

    - 17 - 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...

  • Page 18

    - 18 - step action yes no go to 34. You have excessive restriction in combustion-air or vent pipe. Also check for proper vent sizing for installation. 16 35. Continue to observe furnace operation for 20 minutes or until status code starts flashing. 36 36. Does status code 3 flash? 38 37 37. Does a d...

  • Page 19: Status Code 4

    - 19 - 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 for 4 minutes at intermediate heat airflow or until the open switch remakes...

  • Page 20

    - 20 - step action yes no go to 40. Remove tape from door switch, turn power off at main disconnect, and remove jumper across r and w/w1. 41 41. Is the blower wheel firmly mounted on motor shaft? 42 26 42. Does the model plug pl4 match the part number specified on the rating plate? 44 43 43. Replace...

  • Page 21: Status Code 5

    - 21 - 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 yes no go to 1. Turn off gas to the furnace by shutting off the external manual shut-off valv...

  • Page 22

    - 22 - step action yes no go to 26. Do the main burners stay on longer than a few seconds? 36 40 27. Turn off the power and disconnect the jumpers across the r, w/w1, and w2 thermostat terminals. 28 28. Connect a dc microampmeter in series with the flame sensor wire. 29 29. Turn power on and jumper ...

  • Page 23: Status Code 7

    - 23 - 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. St...

  • Page 24: Status Code 8

    - 24 - 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 yes no go to 1. Remove blower door. Disc...

  • Page 25

    - 25 - 4. 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 furnac...

  • Page 26

    - 26 - step action yes no go to 15. Did the medium pressure switch mps make, then break several times at start of cycle before faulting out? 16 17 16. 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. 32 17. Is 24...

  • Page 27: Status Code 10

    - 27 - step action yes no go to 58. Do you have continuity between the gray wire on the medium pressure switch mps and the yellow wire on the low pressure switch? 59 13 59. The gray wire is shorting to the yellow or orange wire that goes to the low pressure switch lps. 12 60. Check the collector box...

  • Page 28: Status Code 1 + 2

    - 28 - 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 co...

  • Page 29: Status Code 2 + 5

    - 29 - 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...

  • Page 30: Status Code 3 + 5

    - 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 furna...

  • Page 31

    - 31 - step action yes no go to 25. 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. 13 26 26. You have an open wire or a bad terminal on the yell...

  • Page 32: Status Code 4 + 1

    - 32 - 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. Step action yes no go to 1. Sh...

  • Page 33

    - 33 - step action yes no go to 28. 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 se...

  • Page 34: Status Code 4 + 2

    - 34 - step action yes no go to 46. 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 ...

  • Page 35

    - 35 - step action yes no go to 23. Reconnect pl16 to the inducer motor and put setup switch sw1-6 in the off position. 24 24. Does inducer wheel turn freely? 26 25 25. Replace the inducer motor control (if you have a 2 piece design) or the inducer motor assembly. 8 26. Does the inducer wheel rub ag...

  • Page 36: Status Code 4 + 3

    - 36 - step action yes no go to 61. Does a different status code flash? 7 65 62. Is there any frost build-up on combustion-air inlet? 63 64 63. The problem is caused by reversed vent and combustion-air pipes or some other moist air entering combustion-air pipe. 15 64. You have excessive restriction ...

  • Page 37: Status Code 6 + 1

    - 37 - step action yes no go to 20. Is 24-vac across gray wire on the medium pressure switch mps and c om -24v on modulating furnace control? 22 21 21. 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...

  • Page 38

    - 38 - appendix a board layout and wiring schematics fig. 1 – modulating furnace control 24-v thermostat terminals pl2 – hot surface igniter & inducer motor connector 115-vac (l2) connections 115-vac (l1) line voltage connections eac-1 terminal (1.0 amp max.) pl1 – low voltage main harness connector...

  • Page 39

    - 39 - fig. 2 – wiring schematic 440 08 4001 00

  • Page 40

    - 40 - 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 ...

  • Page 41

    - 41 - figure 3 – ecm blower motor 440 08 4001 00

  • Page 42

    - 42 - appendix c pressure check diagram pressure switch make/break points unit size (btuh) high pressure switch medium pressure switch low pressure switch make point break point make point break point make point break point 60,000 (17.5” casing) 1.21 in.Wc max 1.05 in. Wc +/- 0.06 0.85 in. Wc max 0...

  • Page 43

    - 43 - 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

  • Page 44

    - 44 - tools needed: 1. Pitot tube 2. 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. Filter static pressure...

  • Page 45

    - 45 - appendix e quick reference information pressure switch make/break points unit size (btuh) high pressure switch medium pressure switch low pressure switch make point break point make point break point make point break point 60,000 (17.5” casing) 1.21 in.Wc max 1.05 in. Wc +/- 0.06 0.85 in. Wc ...

  • Page 46

    - 46 - 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...

  • Page 47

    - 47 - using recorded modulating rate (mod%), time of operation at the modulating rate (modt), and maximum heat (maxt) calculate the heat load (hlr) using: hlr = (mod% x modt) + 65 + (100 x maxt) is hlr is hlr>1965 mod% = 40% unit will start the next cycle in intermediate heat for 45 seconds followe...

  • Page 48

    - 48 - replaces: new form: icp eng 3-12 440 08 4001 00