Carrier Understanding 48TC and 48TCD Nomenclature for Air Conditioning Systems

48TC

Table 14 – IGC Board LED Alarm Codes

LED	DESCRIPTION	ACTION TAKEN BY	RESET METHOD	PROBABLE CAUSE
FLASH
		CONTROL
CODE
On	Normal Operation	—	—	—
				Loss of power to the IGC. Check 5 amp
Off	Hardware Failure	No gas heating.	—	fuse on IGC, power to unit, 24V circuit
				breaker, transformer, and wiring to the
				IGC.
				High temperature limit switch is open.
		Gas valve and igniter		Check the operation of the indoor
				(evaporator) fan motor.
2	Limit Switch Fault	Off.	Limit switch closed,
				Ensure that the supply-air temperature
Flashes		Indoor fan and inducer	or heat call (W) Off.
		On.		rise is within the range on the unit
				nameplate. Check wiring and limit switch
				operation.
3	Flame Sense Fault	Indoor fan and inducer	Flame sense normal.	The IGC sensed a flame when the gas
Flashes		On.	Power reset for LED	valve should be closed. Check wiring,
			reset.	flame sensor, and gas valve operation.
4	Four Consecutive Limit	No gas heating.	Heat call (W) Off.	4 consecutive limit switch faults within a
			Power reset for LED
Flashes	Switch Fault			single call for heat. See Limit Switch Fault.
			reset.
				Unit unsuccessfully attempted ignition for
			Heat call (W) Off.	15 minutes. Check igniter and flame
5	Ignition Fault	No gas heating.		sensor electrode spacing, gaps, etc.
			Power reset for LED
Flashes				Check flame sense and igniter wiring.
			reset.	Check gas valve operation and gas
				supply.
		If heat off: no gas	Inducer sense	Inducer sense On when heat call Off, or
6	Induced Draft Motor			inducer sense Off when heat call On.
		heating.
			normal, or heat call	Check wiring, voltage, and operation of
Flashes	Fault	If heat on: gas valve
			(W) Off.	IGC motor. Check speed sensor wiring to
		Off and inducer On.
				IGC.
7		Gas valve and igniter		Rollout switch has opened. Check gas
	Rollout Switch Lockout	Off.	Power reset.	valve operation. Check induced-draft
Flashes		Indoor fan and inducer		blower wheel is properly secured to motor
		On.		shaft.
				IGC has sensed internal hardware or
8				software error. If fault is not cleared by
	Internal Control Lockout	No gas heating.	Power reset.	resetting 24 v power, replace the IGC.
Flashes
				Check gas valve connections to IGC
				terminals. BRN lead must be on Pin 11.
9	Temporary Software	No gas heating.	1 hour auto reset, or	Electrical interference is disrupting the
Flashes	Lockout		power reset.	IGC software.

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.

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