Carrier 48HJ004---007, 48HE003---006 Heating Service Analysis, Problem Cause Remedy

	Table 42— Heating Service Analysis
PROBLEM	CAUSE	REMEDY
Burners Will Not	Misaligned spark electrodes.	Check flame ignition and sensor electrode positioning. Adjust as needed.
Ignite.
	No gas at main burners.	Check gas line for air purge as necessary. After purging gas line of air, allow gas
		to dissipate for at least 5 minutes before attempting to relight unit.
		Check gas valve.
	Water in gas line.	Drain water and install drip leg to trap water.
	No power to furnace.	Check power supply, fuses, wiring, and circuit breaker.
	No 24 v power supply to control circuit.	Check transformer. Transformers with internal overcurrent protection require a
		cool-down period before resetting. Check 24-v circuit breaker; reset if neces-
		sary.
	Miswired or loose connections.	Check all wiring and wirenut connections.
	Burned-out heat anticipator in thermostat.	Replace thermostat.
	Broken thermostat wires.	Run continuity check. Replace wires, if necessary.
Inadequate Heating.	Dirty air filter.	Clean or replace filter as necessary.
	Gas input to unit too low.	Check gas pressure at manifold. Clock gas meter for input. If too low, increase
		manifold pressure or replace with correct orifices.
	Unit undersized for application.	Replace with proper unit or add additional unit.
	Restricted airflow.	Clean filter, replace filter, or remove any restrictions.
	Blower speed too low.	Use high speed tap, increase fan speed, or install optional blower, as suitable
		for individual units, Adjust pulley.
	Limit switch cycles main burners.	Check rotation of blower, thermostat heat anticipator settings, and temperature
		rise of unit. Adjust as needed.
	Too much outdoor air.	Adjust minimum position.
		Check economizer operation.
Poor Flame	Incomplete combustion (lack of	Check all screws around flue outlets and burner compartment. Tighten as nec-
Characteristics.	combustion air) results in:	essary.
	Aldehyde odors, CO (carbon monoxide),	Cracked heat exchanger.
	sooting flame, or floating flame.
		Overfired unit — reduce input, change orifices, or adjust gas line or manifold
		pressure.
		Check vent for restriction. Clean as necessary.
		Check orifice to burner alignment.
Burners Will Not	Unit is locked into Heating mode for a	Wait until mandatory one-minute time period has elapsed or reset power to
Turn Off.	one minute minimum.	unit.

Table 43—Humidi-MiZer™Adaptive Dehumidification System Subcooling Mode Service Analysis

PROBLEM	CAUSE		REMEDY
Subcooling Mode (Liquid Reheat)	No power to control transformer from	Check power source and evaporator-fan relay. Ensure all
Will Not Energize.	evaporator-fan motor.	wire connections are tight.
	No power from control transformer to liquid line	1.	Fuse open; check fuse. Ensure continuity of wiring.
	solenoid valve.	2.	Low-pressure switch open. Cycle unit off and allow
			low-pressure switch to reset. Replace switch if it will
			not close.
		3. Transformer bad; check transformer.
	Liquid line solenoid valve will not operate.	1.	Solenoid coil defective; replace.
		2.	Solenoid valve stuck open; replace.
	Liquid line solenoid valve will not open.	Valve is stuck closed; replace valve.
Low System Capacity.	Low refrigerant charge or frosted evaporator coil.	1.	Check charge amount. Charge per Fig. 64-67.
		2.	Evaporator coil frosted; check and replace low-pres-
			sure switch if necessary.
Loss of Compressor Superheat	Thermostatic expansion valve (TXV).	1.	Check TXV bulb mounting, and secure tightly to suc-
Conditions with Subcooling/Reheat		2.	tion line.
Dehumidification Coil Energized.			Replace TXV if stuck open or closed.

Table 44—Humidi-MiZer™Adaptive Dehumidification System Hot Gas Reheat Mode Service Analysis

PROBLEM	CAUSE		REMEDY
Reheat Mode Will Not Energize.	No power to control transformer from	Check power source and evaporator-fan relay. Ensure all
	evaporator-fan motor.	wire connections are tight.
	No power from control transformer to hot gas	1.	Fuse open; check fuse. Ensure continuity of wiring.
	line solenoid valve	2.	Low-pressure switch open. Cycle unit off and allow
			low-pressure switch to reset. Replace switch if it will
			not close.
		3. Transformer bad; check transformer.
	Hot gas line solenoid valve will not operate.	1.	Solenoid coil defective; replace.
		2.	Solenoid valve stuck closed; replace.
	Low refrigerant charge or frosted evaporator coil.	1.	Check charge amount. Charge per Fig. 64---67.
		2.	Evaporator coil frosted; check and replace low-pres-
			sure switch if necessary.
Loss of Compressor Superheat	Thermostatic expansion valve (TXV).	1.	Check TXV bulb mounting, and secure tightly to suc-
Conditions with Subcooling/Reheat		2.	tion line.
Dehumidification Coil Energized.			Replace TXV if stuck open or closed.
Excessive Superheat.	Liquid line solenoid valve will not operate.	Valve is stuck, replace valve.
	Hot gas line solenoid valve will not close.	Valve is stuck; replace valve.

48HE,HJ

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