TROUBLESHOOTING
Table 21 — LED Error Code Service Analysis
PROBLEM 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 trans-
former. If the overload trips, allow 10 minutes for auto-
matic reset.
Limit switch fault.
(LED 2 flashes)
High temperature limit switch is open. Check the operation of the indoor (evaporator) fan mo-
tor. Ensure that the supply-air temperature rise is in ac-
cordance 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 trips.
(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 sense and ignition wires are prop-
erly terminated. Verify that unit is obtaining proper
amount of gas.
Induced-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: PIN 1 — White, PIN 2 — Red, PIN 3
— Black.
Rollout switch fault.
(LED 7 flashes)
Rollout switch has opened. Rollout switch will automatically reset, but IGC will con-
tinue to lockout unit. Check gas valve operation. 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, re-
place the IGC.
If the IGC must be replaced, be sure to ground yourself to dis-
sipate any electrical charge that may be present before han-
dling 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 22 — Heating Service Analysis
for additional troubleshooting analysis.
LEGEND
IGC — Integrated Gas Unit Controller
LED — Light-Emitting Diode
34
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