Emerson DE, VH, VE, DH 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 wiring
Compressor will not	Current overload open	Reset manually
start	Loose electrical connections	Tighten connections
	Compressor motor burned out	Check and replace compressor if defective.
	No call for cooling	Check monitor status.
Compressor will not	Solenoid valve not energizing	Hold screwdriver over solenoid and check for magnetic field.
operate, contactor not		This indicates solenoid is energized.
pulling in
	Low pressure switch not making	Check gas pressure - manually energize low pressure
	contact	switch.
Compressor will not		Reset switch. Refer to other refrigeration troubleshooting
operate, contact not	High pressure switch open
		suggestions.
pulling in
Compressor contactor
pulled in but	Blown fuse or tripped CB	Check for line voltage after fuses or CBs, and after
compressor will not		contactors.
operate
Compressor runs for	Low pressure switch not closing	Check for low gas pressure. Compressor is running on
three minutes then		Positive Start Kit (air cooled systems only).
stops; contactor drops
out. Motor operates but	Solenoid not opening	Check magnetic field to see if energized.
valve won't open
	Dirty condenser or drycooler fins	Clean coil
	Condenser equipment not	Check operation.
	operating
High discharge	High refrigerant charge	Check refrigerant charge.
pressure
	Hot gas bypass valve adjusted	Adjust properly.
	improperly
	Water regulating valve adjusted	Adjust properly.
	improperly
	Excessive water now through	Adjust water regulating valve
	condenser
	Suction service valve partially	Open the valve.
	closed
Low discharge pressure	Leaky compressor suction valves	Pump down, remove the cylinder head, examine valves and
		valve seats; replace if necessary
	Worn piston rings	Replace compressor.
	Faulty head pressure control
	valve or condenser fan speed	Replace if defective.
	control
	Insufficient refrigerant in system	Check for leaks, repair, and add refrigerant
	Dirty air filters	Change filters.
	Plugged filter-drier	Replace filter.
	Improper superheat adjustment	Reset expansion valve for 10-15°F
Low suction pressure	Defective expansion valve	Replace element
	sensing element
	Poor air distribution	Check duct work for closed dampers. Check for underfloor
		restrictions at or near the unit.
	Low condensing pressure	Check head pressure control device.
	Slipping belts	Inspect and adjust

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