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15.1.1. Relationship Between The Condition of The Air Conditioner and Pressure and
Electric Current
• Carry out the measurements of pressure, electric current, and temperature fifteen minutes after an operation is started.
15.1.2. Diagnosis Methods Of A Malfunction Of A Compressor And 4-way Valve
Cooling Mode Heating Mode
Condition of the air
conditioner
Low Pressure High Pressure Electric current
during operation
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
Nature of fault Symptom
• Electric current during operation becomes approximately 20% lower than the normal value.
Insufficient compressing of a compressor • The discharge tube of the compressor becomes abnormally hot (normally 70 to 90°C).
• The difference between high pressure and low pressure becomes almost zero.
• Electric current reaches a high level abnormally, and the value exceeds the limit of an
ammeter. In some cases, a breaker turns off.
Locked compressor
• The compressor has a humming sound.
• Electric current during operation becomes approximately 80% lower than the normal value.
Insufficient switches of the 4-way valve
• The temperature different between from the discharge tube to the 4-way valve and from
suction
• tube to the 4-way valve becomes almost zero.
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