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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
• • Scroll compressor seals leaking
• Too much compressor oil in system
• Faulty oil pump in compressor
• Loose compressor pulley
• Compressor bearing loose or burned out
• • • • • Broken discharge check valve in compressor
• • Expansion valve power element lost its charge
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