46
LEGEND
Table 12 — IGC Board LED Alarm Codes
a,b
a. Alarm codes on the IGC will be lost if power to the unit is interrupted.
b. If the pressure switch is stuck closed on a W1 call, then the unit will sit idle and do nothing with no fault on the IGC.
LED
FLASH
CODE
c,d
c. There is a 3-second pause between alarm code displays.
d. If more than one alarm code exists, all applicable alarm codes will be displayed in numerical sequence.
DESCRIPTION
ACTION TAKEN BY
CONTROL
RESET METHOD PROBABLE CAUSE
On Normal Operation — — —
Off Hardware Failure No gas heating.
—
Loss of power to the IGC. Check 5 amp fuse
on IGC, power to unit, 24V circuit breaker,
transformer, and wiring to the IGC.
1 Flash Indoor Fan On/Off Delay
Modified
5 seconds subtracted from
On delay.
Power reset. High temperature limit switch opens during
heat exchanger warm-up period before fan-
on delay expires.
2 Flashes Limit Switch Fault Gas valve and igniter Off.
Indoor fan and inducer On.
Limit switch closed, or
heat call (W) Off.
High temperature limit switch is open. Check
the operation of the indoor (evaporator) fan
motor.
Ensure that the supply-air temperature rise is
within the range on the unit nameplate.
Check wiring and limit switch operation.
3 Flashes Flame Sense Fault Indoor fan and inducer On. Flame sense normal.
Power reset for LED reset.
The IGC sensed a flame when the gas valve
should be closed. Check wiring, flame
sensor, and gas valve operation.
4 Flashes Four Consecutive Limit Switch
Fault
No gas heating. Heat call (W) Off.
Power reset for LED reset.
4 consecutive limit switch faults within a
single call for heat. See Limit Switch Fault.
5 Flashes Ignition Fault No gas heating. Heat call (W) Off.
Power reset for LED reset.
Unit unsuccessfully attempted ignition for 15
minutes.
Check igniter and flame sensor electrode
spacing, gaps, etc. Check flame sense and
igniter wiring. Check gas valve operation and
gas supply.
6 Flashes Induced Draft Motor
Fault
If heat off: no gas heating.
If heat on: gas valve Off and
inducer On.
Inducer sense normal, or
heat call (W) Off.
Inducer sense On when heat call Off, or
inducer sense Off when heat call On. Check
wiring, voltage, and operation of IGC motor.
Check speed sensor wiring to IGC.
7 Flashes Rollout Switch Lockout Gas valve and igniter Off.
Indoor fan and inducer On.
Power reset. Rollout switch has opened. Check gas valve
operation. Check induced-draft blower wheel
is properly secured to motor shaft.
8 Flashes Internal Control Lockout No gas heating. Power reset. IGC has sensed internal hardware or
software error. If fault is not cleared by
resetting 24 v power, replace the IGC.
9 Flashes Temporary Software Lockout No gas heating. 1 hour auto reset, or power
reset.
Electrical interference is disrupting the IGC
software.
IGC — Integrated Gas Unit Control
LED — Light-Emitting Diode
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