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TROUBLESHOOTING
I. UNIT TROUBLESHOOTING
Refer to Tables 32-36.
SYMPTOM
Hardware Failure
(LED OFF)
Fan ON/OFF Delay Modified
(LED/FLASH)
Limit Switch Fault
(LED 2 Flashes)
Flame Sense Fault
(LED 3 Flashes)
4 Consecutive Limit
Switch Faults
(LED 4 Flashes)
Ignition Lockout
(LED 5 Flashes)
Induced-Draft Motor Fault
(LED 6 Flashes)
Rollout Switch Fault
(LED 7 Flashes)
Internal Control Fault
(LED 8 Flashes)
Temporary Software
Lockout
(LED 9 Flashes)
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 pre-
cautions are not taken.
Table 32 — LED Error Code Service Analysis
CAUSE
Loss of power to control module (IGC).
High limit switch opens during heat
exchanger warm-up period before fan-on
delay expires.
Limit switch opens within three minutes
after blower-off delay timing in Heating mode.
High temperature limit switch is open.
The IGC sensed flame that should not be
present.
Inadequate airflow to unit.
Unit unsuccessfully attempted ignition for
15 minutes.
IGC does not sense that induced-draft
motor is operating.
Rollout switch has opened.
Microprocessor has sensed an error in the
software or hardware.
Electrical interference is impeding the IGC
software.
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
10 minutes for automatic reset.
IGC board has modified either blower on delay time or blower off
delay time.
Check the operation of the indoor (evaporator) fan motor.
Ensure that the supply-air temperature rise is in accordance with
the range on the unit nameplate.
Reset unit. If problem persists, replace control board.
Check operation of indoor (evaporator) fan motor and that supply-air
temperature rise agrees with range on unit nameplate information.
Check ignitor and flame sensor electrode spacing, gaps, etc.
Ensure that flame sense and ignition wires are properly routed
and terminated. Verify that unit is obtaining proper amount of gas.
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 will automatically reset, but IGC will continue to
lock out unit. Check gas valve operation. Ensure that induced-
draft blower wheel is properly secured to motor shaft.
Reset unit at unit disconnect.
If error code is not cleared by resetting unit power, replace the IGC.
Reset 24-v to control board or turn thermostat off and then on.
Fault will automatically reset itself in one hour.
IMPORTANT: Refer to heating troubleshooting for additional heating
section troubleshooting information.
LEGEND
IGC — Integrated Gas Unit Controller
LED — Light-Emitting Diode
—
45
—
REMEDY
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Table of Contents
Troubleshooting
