Liebert 3000 manual Compressor and refrigeration system troubleshooting

		Troubleshooting
Table 23 Compressor and refrigeration system troubleshooting (continued)
Symptom	Possible Cause	Check or Remedy
	Defective or improperly set expansion	Increase superheat or replace valve
Flooding	valve
	Evaporator fan motor or belt	Correct problem or replace fan motor and/
		or belts.
	Low condensing pressure	Check head pressure control device
	Slipping belts	Inspect and adjust
	Compressor rotation in reverse	Check for proper power phase wiring to
Low compressor capacity or	direction.	unit and to compressor motor.
inability to pull down system
	Leaking liquid line solenoid valve or dirt	Replace valve if clean; clean out valve if
	in valve	dirty.
Compressor noisy	Loose compressor or piping support	Tighten clamps.
Pipe rattle	Loose pipe connections	Check pipe connections
	Compression ratio too high	Check setting of high and low pressure
Compressor running hot		switches. Check condenser -- is it
		plugged? Check that all evaporator and
		condenser fans are operating properly.
	Low-pressure switch erratic in operation	Check tubing to switch to see if clogged or
Compressor cycles intermittently		crimped. Check for proper switch
		operation.
	Insufficient refrigerant in system	Check for leaks, fix, and add refrigerant on
		air cooled unit. Evacuate and recharge
		water/glycol unit.
	Suction service valve closed	Open valve.
	Insufficient fluid flowing through	Adjust fluid regulating valve to condenser.
	condenser or clogged condenser, or	Flush the condenser.
	dirty air cooled condenser coils
	Discharge service valve not fully open	Open valve
Compressor cycles continually	Faulty low pressure switch	Repair or replace.
	Dirt or restriction in tubing to pressure	Check and clean tubing.
	stat
	Defective liquid line solenoid valve	Check valve and solenoid operator;
		replace if necessary.
	Plugged filter-drier	Replace filter.
	High discharge pressure	Check for loss of condenser water or
Compressor motor protectors		blocked condenser fan or coil.
tripping or cycling
	Defective overload relay	Replace.
	High suction temperature	Reduce suction temperature by expansion
		valve adjustment or provide
		desuperheating.
	Loose power or control circuit wiring	Check all power and control circuit
	connection	connections.
	Defective motor	Check for motor ground or short. Replace
		compressor, if either condition is found.
	Low line voltage	Check line voltage and determine location
Compressor cycles on locked rotor		of voltage drop.
	Compressor motor defective	Check for motor winding short or ground.
	Single phasing	Check voltage across all 3 legs at
		contactor. Correct source problem.
	Check control panel for welded	Replace defective components
Motor burnout	contactor contacts or welded overload
	contacts

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