TROUBLESHOOTING
Table 18 Ð LED Error Code Service Analysis
PROBLEM | CAUSE | REMEDY |
Hardware failure. | Loss of power to IGC. | Check |
(LED Off) |
| transformer. Units without a |
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| load in the |
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| automatic reset. |
Limit switch fault. | Check the operation of the indoor (evaporator) fan motor. Ensure that | |
(LED 2 Flashes) | is open. | the |
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| unit nameplate. |
Flame sense fault. | The IGC sensed ¯ame that | Reset unit. If problem persists, replace control board. |
(LED 3 Flashes) | should not be present. |
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4 consecutive limit switch trips. | Inadequate air¯ow to unit. | Check operation of indoor (evaporator) fan motor and that |
(LED 4 Flashes) |
| temperature rise agrees with range on unit nameplate information. |
Ignition lockout. | Unit unsuccessfully attempted | Check ignitor and ¯ame sense electrode spacing, gas, etc. Ensure that |
(LED 5 Flashes) | ignition for 15 minutes. | ¯ame sense and ignition wires are properly terminated. Verify that unit |
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| is obtaining proper amount of gas. |
IGC does not sense that | Check for proper voltage. If motor is operating, check the speed sensor | |
(LED 6 Flashes) | plug/IGC Terminal J2 connection. Proper connection: PIN | |
|
| PIN |
Rollout switch fault. | Rollout switch has opened. | Rollout switch will automatically reset, but IGC will continue to lock out |
(LED 7 Flashes) |
| unit. Check gas valve operation. Ensure that |
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| wheel is properly secured to motor shaft. Reset unit at unit disconnect. |
Internal control fault. | Microprocessor has sensed an | If error code is not cleared by resetting unit power, replace the IGC. |
(LED 8 Flashes) | error in the software or hardware. |
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LEGEND
IGC Ð Integrated Gas Unit Controller
LED Ð
WARNING: If the IGC must be replaced, be sure to ground yourself to dissipate any electrical charge that may be present before handling new control board. The IGC is sensitive to static electricity and may be damaged if the necessary precautions are not taken.
IMPORTANT: Refer to Table 19 Ð Heating Service Analysis for ad- ditional troubleshooting analysis.
Table 19 Ð Heating Service Analysis
PROBLEM | CAUSE | REMEDY |
Burners will not | Misaligned spark electrodes. | Check ¯ame ignition and sensor electrode positioning. Adjust as needed. |
ignite. | No gas at main burners. | Check gas line for air, purge as necessary. After purging gas line of air, allow gas |
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| to dissipate for at least 5 minutes before attempting to relight unit. |
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| Check gas valve. |
| Water in gas line. | Drain water and install drip leg to trap water. |
| No power to furnace. | Check power supply, fuses, wiring, and circuit breaker. |
| No 24 v power supply to | Check transformer. Transformers with internal overcurrent protection require a cool |
| control circuit. | down period before resetting. Check |
| Miswired or loose connections. | Check all wiring and wirenut connections. |
| Replace thermostat. | |
| thermostat. |
|
| Broken thermostat wires. | Run continuity check. Replace wires, if necessary. |
Inadequate heating. | Dirty air ®lter. | Clean or replace ®lter as necessary. |
| Gas input to unit too low. | Check gas pressure at manifold. Clock gas meter for input. If too low, increase |
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| manifold pressure, or replace with correct ori®ces. |
| Unit undersized for application. | Replace with proper unit or add additional unit. |
| Restricted air¯ow. | Clean ®lter, replace ®lter, or remove any restrictions. |
| Blower speed too low. | Install |
| Limit switch cycles main burners. | Check rotation of blower, thermostat heat anticipator settings, and temperature rise |
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| of unit. Adjust as needed. |
| Too much outdoor air. | Adjust minimum position. |
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| Check economizer operation. |
Poor ¯ame | Incomplete combustion (lack of | Check all screws around ¯ue outlets and burner compartment. Tighten as |
characteristics. | combustion air) results in: | necessary. |
| Aldehyde odors, carbon monoxide, | Cracked heat exchanger. |
| sooting ¯ame, or ¯oating ¯ame. |
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| Over®red unit Ð reduce input, change ori®ces, or adjust gas line or manifold | |
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| |
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| pressure. |
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| Check vent for restriction. Clean as necessary. |
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| Check ori®ce to burner alignment. |
Burners will not | Unit is locked into Heating mode | Wait until mandatory one minute time period has elapsed or reset power to unit. |
turn off. | for a one minute minimum. |
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