Emerson 3000/ITR manual Compressor and refrigeration system troubleshooting

		Troubleshooting
Table 14 Compressor and refrigeration system troubleshooting (continued)
Symptom	Possible Cause	Check or Remedy
	Defective or improperly set expansion	Increase superheat or replace valve
	valve
Flooding	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
		Check setting of high and low pressure
Compressor running hot	Compression ratio too high	switches. Check condenser -- is it
		plugged? Check that all evaporator and
		condenser fans are operating properly.
		Check tubing to switch to see if clogged or
	Low-pressure switch erratic in operation	crimped. Check for proper switch
		operation.
		Check for leaks, fix, and add refrigerant on
	Insufficient refrigerant in system	air cooled unit. Evacuate and recharge
Compressor cycles intermittently		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
	Faulty low pressure switch	Repair or replace.
	Dirt or restriction in tubing to pressure	Check and clean tubing.
	stat
Compressor cycles continually
	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
		blocked condenser fan or coil.
	Defective overload relay	Replace.
		Reduce suction temperature by expansion
Compressor motor protectors	High suction temperature	valve adjustment or provide
tripping or cycling		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
		of voltage drop.
Compressor cycles on locked rotor	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
Motor burnout	contactor contacts or welded overload	Replace defective components
	contacts

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