Refrigeration Diagnosis (Rev. 04/03)
110
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Expansion valve feeler bulb making poor contact
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Expansion valve open too much
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Expansion valve closed too much
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Expansion valve needle eroded or leaking
•• •
Expansion valve partially closed by ice, dirt or wax
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Liquid refrigerant entering compressor
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Restricted line on the low side
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Restricted line on the high side
••• •
Restricted drier
•
Evaporator shutter open
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Evaporator shutter stuck closed
•
Discharge service valve back seated
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Suction service valve back seated
•••• •• •
Faulty three-way valve
•• • ••
Faulty pilot solenoid
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Loose or broken electrical connections
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Thermostat or thermometer out of calibration
••••
Suction pressure gauge out of calibration
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Leaky receiver tank outlet valve
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Leaky bypass check valve
•• • ••
Leaky condenser check valve
Rapid cycling between cool and heat
Unit cools in heat and defrost cycle
Unit heats in refrigeration cycle
High head pressure
Low head pressure
No head pressure
High suction pressure
Low suction pressure
No suction pressure
Unit operating in a vacuum
Receiver sight glass empty
Suction line frosting back
Unable to pump down system
Unable to pull vacuum in low side
Unable to hold vacuum in low side
Noisy compressor
Unit not refrigerating
Unit not heating or defrosting
SYMPTOM
POSSIBLE CAUSES
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