Refrigeration System Diagnosis 14-2
ALL MODELS EXCEPT TCI AND SPECTRUM
Unit operating with reduced heating capacity/DF
Unit Operating with reduced refrigeration capacity
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 vacuum
Receiver sight glass empty
Suction line frosting back
Unable to pump down system
Unable to pull vacuum in compressor
Unable to hold vacuum in compressor
Noisy compressor
Unit not refrigerating
Unit not heating or defrosting
SYMPTOM
POSSIBLE CAUSE
• • • • 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 worn 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
• • Expansion valve open too much
• • Expansion valve closed too much
• • Expansion valve needle eroded or leaking
• • • Expansion valve partially closed by ice, dirt or wax
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