Sterling SCW Series installation manual Problem Possible Cause Solution

Problem	Possible Cause	Solution
		Allow time to cool and reset.
		Check for high/low voltage.
		Voltage must be within plus
	Compressor internal overload	or minus ten percent (±10%)
		of nameplate rating.
	open.
		Check for poor compressor
		electrical connections.
		Check compressor rotation
		on scroll compressors.
	Compressor contactor	Repair or replace.
	holding coil open.
Pump runs,
	Defective fan motor.	Repair or replace.
compressor does not	Fan motor out on overload.	Reset and test.
(cont’d).	Defective freezestat.	Replace.
	Refrigerant low.	Check the refrigerant charge.
	Defective fan cycling control.	Replace.
	Low refrigerant pressure	Sight glass should be clear
		while comperssor runs. Call
	switch contact open.	for service if bubbling or
		foaming.
	Defective pump motor	Repair or replace.
	interlock to compressor
	control circuit.
	Broken wire in the	Locate and repair.
	compressor control circuit.
	Freezestat control setting is	Lower set point to 10°F (6ºC)
		below the leaving water
Pump runs, compressor	too high.	temperature you want with at
		least 15 degrees differential.
cycles at short intervals.		Check refrigeration charge;
	Refrigerant is too low.	check refrigerant sight glass
		for bubbles or a level in the
		glass.
	Improper water/glycol	Be sure the antifreeze
		mixture protection is right for
Leaving water temperature is	mixture.
		the process.
not at set point.	Defective freezestat control.	Replace.
	Refrigerant charge is low.	Call service to find and repair
		the leak. Add refrigerant.
Pump pressure is too high.	Restricted water flow.	Check for partially closed
		valves etc. Be sure all lines
		are properly sized.

SCW Series Central Chilling Stations Page 69 of 77