Liebert 3000 manual Compressor and refrigeration system troubleshooting

		Troubleshooting
Table 23 Compressor and refrigeration system troubleshooting
Symptom	Possible Cause	Check or Remedy
	Power off	Check main switch, fuses or CBs and
Compressor will not start		wiring
	Current overload open	Re-set units with overload option
		manually. Allow compressor to cool for
		internal overloads to reset.
	Loose electrical connections	Tighten connections
	Compressor motor burned out	Check and replace compressor if
		defective.
Compressor will not operate,	No call for cooling	Check monitor status.
	Solenoid valve not energizing	Hold screwdriver over solenoid and check
contactor not pulling in
		for magnetic field. This indicates solenoid
		is energized.
	Low pressure switch not making contact	Check gas pressure - manually energize
		low pressure switch.
Compressor will not operate,	High pressure switch open	Reset switch. Refer to other refrigeration
contact not pulling in		troubleshooting suggestions.
Compressor contactor pulled in but	Blown fuse or tripped CB	Check for line voltage after fuses or CBs,
compressor will not operate		and after contactors.
	Low pressure switch not closing	Check for low gas pressure. Compressor
Compressor runs for three minutes		is running on Positive Start Kit (air cooled
then stops; contactor drops out.		systems only)
	Liquid line solenoid valve not opening	Check magnetic field to see if energized.
High discharge pressure	Dirty condenser or drycooler fins	Clean coil.
	Condenser equipment not operating	Check operation.
	High refrigerant charge	Check refrigerant charge.
	Hot gas bypass valve adjusted	Adjust properly.
	improperly
	Water regulating valve adjusted	Adjust properly.
	improperly
Low discharge pressure	Excessive fluid flow through condenser	Adjust fluid regulating valve
	Suction service valve partially closed	Open the valve.
	Faulty head pressure control valve or	Replace if defective.
	condenser fan speed control
	Compressor rotation in reverse direction	Check for proper power phase wiring to
		unit and to compressor motor.
	Insufficient refrigerant in system	Check for leaks, repair, and add
Low suction pressure		refrigerant for air cooled. Evacuate and
		recharge for water/glycol unit.
	Dirty air filters	Change filters.
	Plugged filter-drier	Replace filter.
	Improper superheat adjustment	Reset expansion valve for 10-15°F
		(6-8°C)
	Defective expansion valve sensing	Replace element
	element
	Poor air distribution	Check duct work for closed dampers.
		Check for under-floor restrictions at or
		near the unit.
	Low condensing pressure	Check head pressure control device.
	Slipping belts	Inspect and adjust

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