Carrier 48SX024-060, 48SS018-060 user manual Heating, Burners will not ignite

Cooling (cont)

SYMPTOM	CAUSE	REMEDY
Integrated control	Blower wheel not secured to shaft	Properly tighten blower wheel to shaft.
motor
	Insufficient voltage at motor	Determine cause and correct.
(units 48SX048,060
208/230 v)	Power connectors not properly	Connectors should snap easily; do not
IFM does not run.	seated	force.
Integrated control	Motor programmed with a delay	Allow a few minutes for motor to shut off.
motor (units	pro®le
48SX048,060
	With thermostat in OFF the voltage	If measured voltage is more than 1¤2, the
208/230 v)	on G,Y1,Y/Y2,W with respect to	thermostat is incompatible with motor. If
IFM runs when it
	common, should be 1¤2 of actual	voltage is less than 1¤2, the motor has failed.
should be off.	low voltage supply
Integrated control	Water dripping into motor	Verify proper drip loops in connector wires.
motor (units
48SX048,060
	Connectors not ®rmly seated	Gently pull wires individually to be sure they
208/230 v) IFM
		are crimped into the housing.
operation is
intermittent.
IFM Ð Evaporator (Indoor) Fan Motor

Heating

SYMPTOM	CAUSE		REMEDY
Burners will not ignite.	Water in gas line	Drain. Install drip leg.
	No power to furnace	Check power supply fuses, wiring, or circuit breaker.
	No 24-v power supply to control	Check transformer.
	circuit	NOTE: Some transformers have internal overcurrent
		protection that requires a cool-down period to reset.
	Miswired or loose connections	Check all wiring and wirenut connections.
	Burned-out heat anticipator in	Replace thermostat.
	thermostat
	Broken thermostat wire	Run continuity check. Replace wire if necessary.
	Misaligned spark electrodes	Check ¯ame ignition and sense electrode positioning.
		Adjust as necessary.
	No gas at main burners	1.	Check gas line for air. Purge as necessary.
			NOTE: After purging gas line of air, wait at least
			5 minutes for any gas to dissipate before attempt-
			ing to light unit.
		2.	Check gas valve.
Inadequate heating.	Dirty air ®lter	Clean or replace ®lter as necessary.
	Gas input to furnace too low	Check gas pressure at manifold. Match with that on
		unit nameplate.
	Unit undersized for application	Replace with proper unit or add additional unit.
	Restricted air¯ow	Clean or replace ®lter. Remove any restriction.
	Blower speed too low	Use faster speed tap if available, or install alternate
		motor.
	Limit switch cycles main burners	Check rotation of blower, thermostat heat antic-
		ipator settings, temperature rise of unit. Adjust as
		necessary.
Poor ¯ame characteristics.	Incomplete combustion results in:	1.	Tighten all screws around burner compartment.
	Aldehyde odors, carbon monox-	2.	Cracked heat exchanger. Replace.
	ide, sooting ¯ame, ¯oating ¯ame	3. Unit over®red. Reduce input (change ori®ces or
			adjust gas line or manifold pressure).
		4.	Check burner alignment.

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