Thermo King RD-MT - Refrigeration Diagnosis; Rapid cycling between Cool and Heat; Unit cools in Heat and Defrost cycle; Unit heats in refrigeration cycle

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Refrigeration Diagnosis
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
•• ••Overcharge of refrigerant
• • •• ••Shortage of refrigerant
••• ••No refrigerant
• Air through condenser too hot (ambient)
• Air flow through condenser restricted
••• Air through condenser too cold (ambient)
•••Air in refrigerant system
• Condenser fan blades bent or broken
• Air short cycling around evaporator coil
• Air through evaporator restricted
••• • Evaporator needs defrosting
••Compressor discharge valves leaking
••Compressor suction valves leaking
• Too much compressor oil in system
• Faulty oil pump in compressor
• Faulty compressor drive coupling
• Compressor bearing loose or burned out
• •••• Broken valve plate in compressor
••Expansion valve power element lost its charge
•• Expansion valve feeler bulb improperly mounted
•••Expansion valve feeler bulb making poor contact