Carrier 30GN040-420 operating instructions Troubleshooting, Standard and Accessory Unloaders

Table 19 Ð Troubleshooting

SYMPTOMS	CAUSE						REMEDY
COMPRESSOR DOES	Power line open						Reset circuit breaker.
NOT RUN	Control fuse open						Check control circuit for ground or short.
							Replace fuse.
	High-Pressure Switch (HPS)						Move LOCAL/ENABLE-STOP-CCN switch to STOP
	tripped						position then back to RUN or CCN position.
	Tripped power breaker						Check the controls. Find cause of trip
							and reset breaker.
	Loose terminal connection						Check connections.
	Improperly wired controls						Check wiring and rewire.
	Low line voltage						Check line voltage. Determine location
							of voltage drop and remedy de®ciency.
	Compressor motor defective						Check motor winding for open or short.
							Replace compressor if necessary.
	Seized compressor						Replace compressor.
COMPRESSOR CYCLES OFF	Loss of charge						Repair leak and recharge.
ON LOW PRESSURE	Bad transducer						Replace transducer.
	Low refrigerant charge						Add refrigerant.
COMPRESSOR SHUTS DOWN	High-pressure control erratic in action						Replace control.
ON HIGH PRESSURE	Compressor discharge valve partially closed						Open valve or replace if defective.
CONTROL
	Condenser fan(s) not operating						Check wiring. Repair or replace motor(s)
							if defective.
	Condenser coil plugged or dirty						Clean coil.
UNIT OPERATES LONG OR	Low refrigerant charge						Add refrigerant.
CONTINUOUSLY	Control contacts fused						Replace control.
	Partially plugged or plugged expansion						Clean or replace.
	valve or ®lter driver
	Defective insulation						Replace or repair.
	Service load						Keep doors and windows closed.
	Inefficient compressor						Check valves. Replace if necessary.
SYSTEM NOISES	Piping vibration						Support piping as required.
	Expansion valve hissing						Add refrigerant.
							Check for plugged liquid line ®lter drier.
	Compressor noisy						Check valve plates for valve noise.
							Replace compressor (worn bearings).
							Check for loose compressor holddown bolts.
COMPRESSOR LOSES OIL	Leak in system						Repair leak.
	Mechanical damage (blown piston or						Repair damage or replace compressor.
	broken discharge valve)
	Crankcase heaters not energized						Replace heaters, check wiring and
	during shutdown						crankcase heater relay contacts.
FROSTED SUCTION LINE	Expansion valve admitting either too						Check cooler and compressor thermistors.
	much or too little refrigerant						Test EXV.
HOT LIQUID LINE	Shortage of refrigerant due to leak						Repair leak and recharge.
FROSTED LIQUID LINE	Shutoff valve partially closed or restricted						Open valve or remove restriction.
COMPRESSOR DOES NOT	Burned out coil						Replace coil.
UNLOAD	Defective capacity control valve						Replace valve.
	Miswired solenoid						Rewire correctly.
	Weak, broken, or wrong valve body spring						Replace spring
COMPRESSOR DOES NOT	Miswired solenoid						Rewire correctly.
LOAD	Defective capacity control valve						Replace valve.
	Plugged strainer (high side)						Clean or replace strainer.
	Stuck or damaged unloader piston or						Clean or replace the necessary parts.
	piston ring(s)
EXV Ð Electronic Expansion Valve
	Table 20 Ð Standard and Accessory Unloaders
					NO. OF ACCESSORY
	UNIT	NO. OF STANDARD				UNLOADERS
			UNLOADER(s)			PERMITTED
					Circuit A			Circuit B
	30GN040-070			1		1		1 or 2
	30GN080-170*			2		1		1
	30GN190-210*			0		1		1

*And associated modular units.

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