Carrier 48TC 17 Series Service And Maintenance Instructions page 50

LED
FLASH DESCRIPTION
CODE
On Normal Operation
Off Hardware Failure
2
Limit Switch Fault
Flashes
3
Flame Sense Fault
Flashes
4 Four Consecutive Limit
Flashes Switch Fault
5
Ignition Fault
Flashes
6 Induced Draft Motor
Flashes Fault
7
Rollout Switch Lockout
Flashes
8
Internal Control Lockout
Flashes
9 Temporary Software
Flashes Lockout
LEGEND
IGC - Integrated Gas Unit Control
LED - Light-Emitting Diode
NOTES:
1. There is a 3-second pause between alarm code displays.
2. If more than one alarm code exists, all applicable alarm codes will be displayed in numerical sequence.
3. Alarm codes on the IGC will be lost if power to the unit is interrupted.
Table 18 – IGC Board LED Alarm Codes
ACTION TAKEN BY
RESET METHOD
CONTROL
—
No gas heating.
Gas valve and igniter
Off. Limit switch closed,
Indoor fan and inducer or heat call (W) Off.
On.
Flame sense normal.
Indoor fan and inducer
Power reset for LED
On.
reset.
Heat call (W) Off.
No gas heating. Power reset for LED
reset.
Heat call (W) Off.
No gas heating. Power reset for LED
reset.
If heat off: no gas
Inducer sense nor­
heating.
mal, or heat call (W)
If heat on: gas valve
Off.
Off and inducer On.
Gas valve and igniter
Off.
Power reset.
Indoor fan and inducer
On.
No gas heating. Power reset.
1 hour auto reset, or
No gas heating.
power reset.
50
PROBABLE CAUSE
—
Loss of power to the IGC. Check 5 amp
fuse on IGC, power to unit, 24V circuit
—
breaker, transformer, and wiring to the
IGC.
High temperature limit switch is open.
Check the operation of the indoor (evapo­
rator) fan motor.
Ensure that the supply‐air temperature
rise is within the range on the unit name­
plate.
Check wiring and limit switch operation.
Check/clean return air filters.
Check burner assembly manifold pressure
to ensure proper firing rate.
The IGC sensed a flame when the gas
valve should be closed. The minimum
flame sensing microamps is 0.5 mA.
Check wiring, flame sensor, and gas valve
operation.
4 consecutive limit switch faults within a
single call for heat. See Limit Switch Fault.
Unit unsuccessfully attempted ignition for
15 minutes. Check igniter and flame sen­
sor electrode spacing, gaps, etc. Check
flame sense and igniter wiring. Check gas
valve operation and gas supply.
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.
Check to ensure Hall Effect wires are not
rubbing against cabinet sheet metal.
Rollout switch has opened. Check gas
valve operation.
Check induced‐draft blower wheel is prop­
erly secured to motor shaft.
IGC has sensed internal hardware or soft­
ware error. If fault is not cleared by reset­
ting 24V power, replace the IGC.
Check gas valve connections to IGC ter­
minals. BRN lead must be on Pin 11.
Check that W1, W2, and Com are correct­
ly connected to the gas valve terminals.
Electrical interference is disrupting the
IGC software.
—