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16.1.1  Relationship Between the Condition of the Air Conditioner and Pressure and 
Electric Current 
 
Cooling Mode 
Condition of the  
air conditioner 
Low Pressure  High Pressure  Electric current during operation
Insufficient refrigerant 
(gas leakage) 
     
Clogged capillary tube or 
strainer 
     
Short circuit in the indoor unit 
     
Heat radiation deficiency 
of the outdoor unit 
     
Inefficient compression 
     
•  Carry out the measurement of pressure, electric current, and temperature fifteen minutes after an operation is started. 
 
16.1.2  Diagnosis Methods of a Malfunction of a Compressor 
Nature of fault  Symptom 
Insufficient compressing of a compressor 
•  Electric current during operation becomes approximately 20% lower than the normal value. 
 
•  The discharge tube of the compressor becomes abnormally hot (normally 70°C to 90°C). 
 
•  The different between high pressure and low pressure becomes almost zero. 
Locked compressor 
•  Electric current reaches a high level abnormally, and the value exceeds the limit of an  
   ammeter. In some cases, a breaker turns off. 
 
•  The compressor has a humming sound.