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- 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 YELLOW wire between connector PL8 and

PL17. Repair or replace the wire harness.

8

27.

Put setup switch SW1-6 in the OFF position.

28

28.

Connect a DC voltmeter across terminals PL17-3 ORANGE (+) and PL17-4

GREEN/YELLOW (-). Is there 5-vdc across the ORANGE and GREEN/YELLOW wires?

29

17

29.

Check the gas valve PWM output. To do this connect a DC voltmeter across terminals PL17-

3 ORANGE (+) and PL17-4 GREEN/YELLOW (-) then run COMPONENT TEST by

turning setup switch SW1-6 ON. In approximately 17 seconds the voltage will drop briefly

from 5.0-vdc. The voltage drop will be several volts or more and will last for 1 to 2 seconds.

If everything is working properly this will happen once. If power was reset before running

the COMPONENT TEST there will be 2 shorter duration voltage drops spaced further apart.

The time between these voltage drops depends on whether the valve has been converted to

propane.

30

30.

Does the voltage drop as described in step 29?

31

17

31.

Put setup switch SW1-6 in the OFF position.

32

32.

Connect a DC voltmeter across terminals PL8-3 ORANGE (+) and C

OM

-24V (-)then run

COMPONENT TEST by turning setup switch SW1-6 ON.

33

33.

Does the voltage drop as described in step 29?

13

34

34.

You have an open wire or a bad terminal on the ORANGE wire between connector PL8 and

PL17. Repair or replace wire harness.

8

35.

Does status code 3 + 5 flash when the blower turns on?

37

36

36.

24-vac power to the stepper motor electronics is intermittent. Disconnect connector PL8 and

PL17 and check the terminals at both ends of the RED wire. Repair or replace the wire

harness.

8

37.

Disconnect jumper wire across R and W/W1 thermostat terminals and wait for the blower to

turn off.

38

38.

Disconnect all accessories (humidifiers and/or EAC’s).

39

39.

Jumper the R and W/W1 thermostat terminals.

40

40.

Does status code 3 + 5 flash when the blower turns on?

43

41

41.

One of the accessories disconnected is creating electrical interference with the gas valve.

Either isolate the accessory with a relay or replace the accessory.

42

42.

Fix the problem.

8

43.

Either the blower motor is creating electrical interference with the gas valve or the gas valve

is overly sensitive. Replace the gas valve. If the problem persists replace entire blower motor

including the blower control module.

42

440 08 4001 00

Summary of Contents for 9MAC/E series

Page 1: ...hm 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 heati...

Page 2: ...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 co...

Page 3: ...ted 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...

Page 4: ...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 minimum heat only switch...

Page 5: ...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 t...

Page 6: ...us blower airflow 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...

Page 7: ...Failed or Out of Calibration pressure switches Water in vent piping possible sagging pipe Disconnected or obstructed pressure tubing 4 LIMIT CIRCUIT FAULT Indicates the limit or flame rollout is open...

Page 8: ...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...

Page 9: ...status code other than the heartbeat 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 simultaneousl...

Page 10: ...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 18 32 Turn power off Remove secondary voltage...

Page 11: ...ce 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 14 Does the furnace operate properly in cooling mode...

Page 12: ...116 1302 1488 18601 DEF 5T 60 4882 6512 651 814 976 814 6512 814 976 9761 1139 1139 1139 1302 1302 1139 16271 16271 1139 1627 1953 DEF DEF DEF 3 5T 60 80 5T 80 100 BASED ON 325 CFM TON SETUP SWITCH SW...

Page 13: ...d 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 fai...

Page 14: ...energized Note On the modulating furnace control the HUM terminal is energized when the blower turns ON 3 18 18 Disconnect jumper wire across R and W W1 thermostat terminals and wait until blower stop...

Page 15: ...r stops 49 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...

Page 16: ...on modulating furnace control 11 12 11 The main harness is miswired 7 12 Is 24 vac across VIOLET wire on the medium pressure switch MPS and COM 24V on modulating furnace control 15 13 13 Is 24 vac acr...

Page 17: ...Is 24 vac across YELLOW wire on the low pressure switch LPS and COM 24V on modulating furnace control 14 10 10 Is 24 vac across connector terminal PL1 2 and COM 24V on modulating furnace control 11 13...

Page 18: ...blem still persists and wind conditions are not excessive turn setup switch SW1 3 ON to boost inducer speed On the Communicating Wall Control select MIN INT RISE ADJ 8 45 Check for partially clogged d...

Page 19: ...power off 15 15 Do you have continuity across limit switch LS 19 16 16 Wait for unit to cool then recheck for continuity across limit switch LS 17 17 Do you have continuity across limit switch LS 19 1...

Page 20: ...The setpoint is 170 deg F but the switch opens at a temperature below 160 deg F 18 56 56 The problem may be related to poor air distribution or excessive pressure drop across filter Check filter and r...

Page 21: ...ex for the section covering the status code INDEX 8 Go to page number indicated in Index for CLEANUP AND START UP INSTRUCTIONS INDEX 9 Turn off the power and disconnect the jumper across the R and W W...

Page 22: ...heat 37 8 40 Turn off the power and disconnect the jumper across the R and W W1 thermostat terminals 41 41 Turn power on and jumper R W W1 and W2 thermostat terminals 42 42 Do the main burners ignite...

Page 23: ...10 17 Do you have continuity across each flame rollout switch FRS 25 18 18 Can flame rollout switch FRS be reset 20 19 19 Replace flame rollout switch FRS 10 20 Reset flame rollout switch FRS install...

Page 24: ...PUT OPERATION 40 51 OF MAXIMUM HEAT 40 45 OF MAXIMUM HEAT ON 5T 060 1 STEADY STATE If the medium pressure switch input turns ON the modulating furnace control begins flashing status code 9 and continu...

Page 25: ...ating furnace control ramps inducer RPM up until the high pressure switch HPS remakes When the high pressure switch HPS remakes the modulating furnace control continues the heating cycle If high press...

Page 26: ...and disconnect jumper wire across R and W W1 thermostat terminals 38 38 Connect 1 side of slope manometer with a tee to collector box pressure tap Refer to pressure check diagram in Appendix C 39 39 T...

Page 27: ...akers or manual disconnects to the problem unit correctly set 11 10 10 Fix problem 5 11 Are the Auxiliary Limit switches properly set 12 10 12 Do you have 115 vac across L1 and L2 in the problem unit...

Page 28: ...iter HSI come on during the cycle 15 24 15 Disconnect the humidifier lead from HUM terminal on modulating furnace control 16 16 Does the furnace still alternately cycle induced draft motor IDM and blo...

Page 29: ...p switch SW1 6 in the ON position 9 10 9 Put setup switch SW1 6 in the OFF position 5 10 Is this a new service replacement control 19 13 11 You need to remove the model plug PL4 from the old control a...

Page 30: ...from the furnace control board 2 2 Turn the power on and depress the door switch Use a piece of tape to hold it closed 3 3 Jumper the R and W W1 thermostat terminals 4 4 Observe the operation of the f...

Page 31: ...30 Does the voltage drop as described in step 29 31 17 31 Put setup switch SW1 6 in the OFF position 32 32 Connect a DC voltmeter across terminals PL8 3 ORANGE and COM 24V then run COMPONENT TEST by t...

Page 32: ...door switch Use a piece of tape to hold it closed 19 19 Do you have 115 vac across the BLACK blower motor wire connected to L1 and the WHITE blower motor wire connected to L2 21 20 20 Replace the mod...

Page 33: ...rminals PL13 3 BLUE and PL13 4 GREEN Does the voltage fluctuate as described in step 28 15 32 32 You have an open wire or bad terminal on the BLUE wire between connectors PL3 and PL13 Repair it or rep...

Page 34: ...ex for the section covering the status code INDEX 8 Go to page number Indicated in Index for CLEANUP AND START UP INSTRUCTIONS INDEX 9 Does the inducer motor turn on 27 10 10 Hook an AC voltmeter acro...

Page 35: ...ng in direction shown on inducer housing 41 25 41 Turn power off and disconnect jumper from the R and W W1 thermostat terminals 49 42 Connect 1 side of slope manometer with a tee to collector box pres...

Page 36: ...the furnace until ignition 5 5 Does status code 4 3 flash 9 6 6 Does a different status code flash 7 8 7 Go to page number indicated in the Index for the section covering the status code INDEX 8 Go to...

Page 37: ...or is not running during lockout refer to status code 6 If the inducer motor is running at full speed during lockout this indicates that flame sense was lost 3 times within 60 minutes of cumulative ga...

Page 38: ...ECTOR PL3 ECM BLOWER HARNESS CONNECTOR TRANSFORMER 24 VAC CONNECTIONS 3 AMP FUSE STATUS AND COMM LED LIGHTS SW1 SETUP SWITCHES AND BLOWER OFF DELAY MODEL PLUG CONNECTOR AIR CONDITIONING A C AIRFLOW SE...

Page 39: ...39 Fig 2 Wiring Schematic 440 08 4001 00...

Page 40: ...ines motor speed Setting up the desired airflow CFM for an ECM blower motor is done by setting the A C or CF selections on the modulating furnace control shown in figure 1 The ECM blower motor then de...

Page 41: ...41 Figure 3 ECM Blower Motor 440 08 4001 00...

Page 42: ...c max 0 70 in wc 0 05 0 62 in wc max 0 47 in wc 0 05 60 000 21 casing 1 46 in wc max 1 29 in wc 0 07 1 00 in wc max 0 85 in wc 0 05 0 64 in wc max 0 49 in wc 0 05 80 000 1 58 in wc max 1 40 in wc 0 08...

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: ...20 in w c Coil Static Pressure Drop Wet 0 20 in w c Total ESP 0 60 in w c Both Examples 1 and 2 are correct Example 1 ESP readings were taken as laid out in static pressure reading location diagrams F...

Page 45: ...amps Hot Surface Igniter Reading The Silicon Nitride igniter in this furnace is not voltage sensitive and will work within the voltage range of 102 to 132 VAC Hence there is no voltage regulation circ...

Page 46: ...um heat operation EXAMPLE 1 Furnace ran for 45 seconds in intermediate heat 19 minutes in minimum heat MOD 40 and 5 minutes at maximum heat during previous call for heat MOD 40 MODT 19 MAXT 5 Calculat...

Page 47: ...m Heat if the call for heat still exists The Modulating rate MOD for this cycle will be as determined Thermostat is satisfied Yes Yes Unit will start the next cycle in Maximum Heat and will remain run...

Page 48: ...48 Replaces New Form ICP Eng 3 12 440 08 4001 00...

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