Refrigeration Diagnosis Chart
Unit Not Heating
Rapid cycling
High Head Pressure
Low head pressure
No head pressure
High suction pressure
Low suction pressure
Unit operating in a vacuum
Sigh glass / Empty
Suction Line frosting back
Noisy compressor
Unit not cooling
SYMPTON
POSSIBLE CAUSES
• • Over charge of refrigerant
• • • • • • Sortage of refrigerant
• • • • • • • No Refrigerant
• Air through condenser too hot (ambient)
• Air flow throught he condenser restricted (dirty)
• • Air through the condneser too cold (ambient)
• • • Air in refrigerant system
• Condneser fan fins bent or broken
• Air short cycling aroung the evaporator coil
• • • Air through the evaporator restricted
• • • • • • Evaporator needs defrosting (iced up)
• • Broken compressor belt
• • • Too much compressor oil in the system
• Loose compressor pulley
• Compressor bearing loose or burnt out
• • Broken valve plate in the compressor
• • • • Expansion valve power element lost its charge
• • • Expansion valve feeler bulb improperly mounted
• • • Expansion valve feeler bulb not 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 or dirt
• Coolant valves not open
• Truck engine not running
• • • • Liquid refrigerant entering compressor
• • • Restricted line on low side
• • Restricted line on high side
• • • Restricted drier
• Reverse fan rotation
• Loose or broken electrical connections
• • • Gauge out of calibration
• Condenser fan motor not operating
• • • • • Evaporator fan not oprating
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