Carrier 50GS, 50GX instruction manual Troubleshooting-Cooling, Symptom Cause Remedy

Table 10—Troubleshooting—Cooling

SYMPTOM	CAUSE	REMEDY
	Power Failure	Call power company
	Fuse blown or circuit breaker tripped	Replace fuse or reset circuit breaker
	Defective thermostat, contractor, transformer, or	Replace component
	control relay
Compressor and condenser 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 temperature
	Faulty wiring or loose connections in compressor	Check wiring and repair or replace
	circuit
Compressor will not start but condenser fan	Compressor motor burned out, seized, or internal	Determine cause
	overload open	Replace compressor
runs.
	Defective run/start capacitor, overload, start relay	Determine cause and replace
	One leg of 3-phase power dead	Replace fuse or reset circuit breaker
		Determine cause
Three-phase scroll compressor (50GS048,	Scroll compressor is rotating	Correct the direction of rotation by reversing the
50GX030-060) makes excessive noise, and		3-phase power leads to the unit. Shut down unit
	in the wrong direction
there may be a low pressure differential.		to allow pressures to equalize.
	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	Blocked condenser	Determine cause and correct
(other than normally satisfying thermostat).	Defective run/start capacitor, overload or start	Determine cause and replace
	relay
	Defective thermostat	Replace thermostat
	Faulty condenser-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
Compressor operates continuously.	Low refrigerant charge	Locate leak, repair, and recharge
	Leaking valves in compressor	Replace compressor
	Air in system	Recover refrigerant, evacuate system, and re-
		charge
	Condenser coil dirty or restricted	Clean coil or remove restriction
	Dirty air filter	Replace filter
	Dirty condenser coil	Clean coil
Excessive head pressure.	Refrigerant overcharged	Recover excess refrigerant
	Air in system	Recover refrigerant, evacuate system, and re-
		charge
	Condenser 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
	High heat load	Check for source and eliminate
Excessive suction pressure.	Compressor valves leaking	Replace compressor
	Refrigerant overcharged	Recover excess refrigerant
	Dirty air filter	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 evaporator airflow	Increase air quantity
		Check filter- replace if necessary
	Temperature too low in conditioned area	Reset thermostat
	Outdoor ambient below 40°F	Install low-ambient kit
	Field-installed filter-drier restricted	Replace

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