Carrier 50JS instruction manual ÐCooling and Heating Troubleshooting Chart

Table 5ÐCooling and Heating Troubleshooting Chart

SYMPTOM	CAUSE	REMEDY
	Power failure	Call power company
	Fuse blown or circuit breaker tripped	Replace fuse or reset circuit breaker
	Defective thermostat, contactor, transformer, con-	Replace component
	trol relay or defrost board
Compressor and outdoor fan will not start	Insufficient line voltage	Determine cause and correct
	Incorrect or faulty wiring	Check wiring diagram and rewire correctly
	Thermostat setting too high	Lower thermostat setting below room tempera-
		ture
		DO NOT bypass this compressor time
	Units have a 5-min. time delay	delayÐwait for 5 min. until time-delay relay is
		deenergized
	Faulty wiring or loose connections in compressor	Check wiring and repair or replace
	circuit
	Compressor motor burned out, seized, or internal	Determine cause
Compressor will not start but condenser fan	overload open	Replace compressor
	Defective run capacitor, overload, or PTC (posi-
runs		Determine cause and replace
	tive temperature coefficient) thermistor
	One leg of 3-phase power dead	Replace fuse or reset circuit breaker
		Determine cause
	Low input voltage (20% low)	Determine cause and correct
Three-phase scroll compressor (size 030-	Scroll compressor is rotating in the wrong direc-	Correct the direction of rotation by reversing the
060units) makes excessive noise, and there
	tion	3-phase power leads to the unit
may be a low pressure differential
	Refrigerant overcharge or undercharge	Recover refrigerant, evacuate system, and re-
		charge to capacities shown on nameplate
	Defective compressor	Replace and determine cause
	Insufficient line voltage	Determine cause and correct
Compressor cycles (other than normally sat-	Blocked outdoor coil	Determine cause and correct
	Defective run/start capacitor, overload or start
isfying thermostat)		Determine cause and replace
	relay
	Defective thermostat	Replace thermostat
	Faulty outdoor-fan motor or capacitor	Replace
	Damaged reversing valve	Determine cause and correct
	Restriction in refrigerant system	Locate restriction and remove
	Dirty air filter	Replace filter
	Unit undersized for load	Decrease load or increase unit size
	Thermostat set too low	Reset thermostat
	Low refrigerant charge	Locate leak, repair, and recharge
	Leaking valves in compressor	Replace compressor
Compressor operates continuously		Check defrost time settings
	Frosted coil with incorrect defrost operation	Reset as necessary
		Check defrost temperature switch
		Replace as necessary
	Air in system	Recover refrigerant, evacuate system, and re-
		charge
	Outdoor coil dirty or restricted	Clean coil or remove restriction
	Dirty air filter	Replace filter
	Dirty indoor or outdoor coil	Clean coil
	Refrigerant overcharged	Recover excess refrigerant
Excessive head pressure
	Air in system	Recover refrigerant, evacuate system, and re-
		charge
	(Heat) Indoor air restricted or recirculating	Determine cause and correct
	Indoor or outdoor air restricted or air short-cycling	Determine cause and correct
	Low refrigerant charge	Check for leaks, repair and recharge
Head pressure too low
	Compressor valves leaking	Replace compressor
	Restriction in liquid tube	Remove restriction
	(Heat) Outdoor coil frosted	Move timer on control board to 30 min. between
		defrost cycles
Excessive suction pressure	(Cool) High Heat load	Check for source and eliminate
	Compressor valves leaking	Replace compressor
	Reversing valve hung up or leaking internally	Replace valve
	Refrigerant overcharged	Recover excess refrigerant

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