Carrier 50ZH024-060 instruction manual ÐTroubleshootingÐCooling and Heating, Symptom Cause Remedy

Table 8ÐTroubleshootingÐCooling and Heating

SYMPTOM	CAUSE	REMEDY
	Power Failure	Call power company
	Loss of Charge	Evaluate unit for possible refrigerant leak
	Switch open
	Fuse blown or circuit breaker tripped	Replace fuse or reset circuit breaker
Compressor and outdoor fan will not start.	Defective thermostat, contractor, transformer, or	Replace component
	control relay
	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
	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 outdoor fan	overload open	Replace compressor
	Defective run/start capacitor, overload, start relay	Determine cause and replace
runs.
	One leg of 3-phase power dead	Replace fuse or reset circuit breaker
		Determine cause
	Low input voltage	Determine cause and correct
	(20 percent low)
	Refrigerant overcharge or undercharge	Recover refrigerant, evacuate system, and re-
		charge to capacities shown on nameplate
	Loss of Charge	Evaluate unit for possible refrigerant leak
	Switch open
	Defective compressor	Replace and determine cause
Compressor cycles	Insufficient line voltage	Determine cause and correct
(other than normally satisfying thermostat).	Blocked outdoor coil (cooling)	Determine cause and correct
	Defective run/start capacitor, overload or start	Determine cause and replace
	relay
	Defective thermostat	Replace thermostat
	Faulty outdoor-fan motor or capacitor	Replace
	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
Compressor operates continuously.	Leaking valves in compressor	Replace compressor
	Frosted outdoor coil with incorrect	Check defrost time settings. Reset as necessary.
	defrost operation (heating)	Check defrost temperature switch. Replace as necessary.
	Air in refrigerant system	Recover refrigerant, evacuate system, and re-
		charge
	outdoor coil dirty or restricted	Clean coil or remove restriction
	Dirty air filter	Replace filter
	Dirty outdoor coil	Clean coil
Excessive head pressure.	Refrigerant overcharged	Recover excess refrigerant
	Air in refrigerant system	Recover refrigerant, evacuate system, and re-
		charge
	Outdoor or indoor air restricted	Determine cause and correct
	or air is recirculating
	Low refrigerant charge	Check for leaks, repair and recharge
Head pressure too low.
	Compressor valves leaking	Replace compressor
	Restriction in liquid tube	Remove restriction
	High heat load	Check for source and eliminate
Excessive suction pressure.
	Compressor valves leaking	Replace compressor
	Refrigerant overcharged	Recover excess refrigerant
	Dirty air filter (cooling)	Replace Filter
	Low refrigerant charge	Check for leaks, repair, and recharge
	Metering device or low side restricted	Remove source of restriction
Suction pressure too low.	Insufficient indoor airflow (cooling)	Increase air quantity
		Check filter- replace if necessary
	Temperature too low in conditioned area (cooling)	Reset thermostat
	Outdoor ambient below 40°F (cooling)	Install low-ambient kit
	Field-installed filter-drier restricted	Replace
Compressor runs but	Normally closed contacts on	Check condition of relay on board.
outdoor fan does not.	defrost board open	Replace board if necessary.

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