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TABLE 12—LED TROUBLESHOOTING–ERROR CODE
SYMPTOM CAUSE REMEDY
Hardware failure.
(LED OFF)
Loss of power to control module (IGC)
Check 5 amp fuse on IGC, power to unit, 24-v
circuit breaker, and transformer. Units without a
24-v circuit breaker have an internal overload in
the 24-v transformer. If the overload trips, allow
20 minutes for automatic reset.
Fan ON/OFF delay modified. (LED/FLASH)
High limit switch opens during heat exchanger
warm-up period before fan-on delay expires
Ensure unit is fired on rate and temperature rise
is correct.
Limit switch opens within three minutes after
blower-off delay timing in Heating mode
Ensure unit’s external static pressure is within
application guidelines.
Limit switch fault. (LED 2 flashes) High temperature limit switch is open
Check operation of indoor (evaporator) fan motor.
Ensure that the supply-air temperature rise is in
accordance with the range on the unit nameplate.
Flame sense fault. (LED 3 flashes) The IGC sensed flame that should not be present
Reset unit. If problem persists, replace control
board.
4 consecutive limit switch faults. (LED 4
flashes)
Inadequate airflow to unit
Check operation of indoor (evaporator) fan motor
and that supply-air temperature rise agrees with
range on unit nameplate information.
Ignition lockout. (LED 5 flashes)
Unit unsuccessfully attempted ignition for 15 min-
utes
Check ignitor and flame sensor electrode spacing,
gaps, etc. Ensure that flame sensor and ignition
wires are properly terminated. Verify that unit is
obtaining proper amount of gas.
Induce-draft motor fault. (LED 6 flashes)
IGC does not sense that induced-draft motor is
operating
Check for proper voltage. If motor is operating,
check the speed sensor plug/IGC Terminal J2
connection. Proper connection:
PIN1–White,
PIN 2 – Red,
PIN3–Black.
Rollout switch fault. (LED 7 flashes) Rollout switch has opened
Rollout switch will automatically reset, but IGC will
continue to lockout unit. check gas valve opera-
tion. ensure that induced-draft blower wheel is
properly secured to motor shaft. Reset unit at unit
disconnect.
Internal control fault. (LED 8 flashes)
Microprocessor has sensed an error in the soft-
ware or hardware
If error code is not cleared by resetting unit
power, replace the IGC.
Internal software fault. (LED 9 flashes)
Microprocessor has sensed an error in it’s redun-
dant software comparison
If error code is not cleared by resetting unit
power, replace the IGC.
CAUTION: 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 Heating Troubleshooting Chart for additional troubleshooting analysis.
LEGEND
IGC – Integrated Gas Unit Controller
LED – Light-Emitting Diode
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