90
15.1.1 Relationship between the condition of the air conditioner and pressure and
electric current
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)
Ô Ô Ô Ô Ô Ô
Clogged capillary tube or
strainer
Ô Ô Ô Ô Ô Ô
Short circuit in the indoor unit
Ô Ô Ô Ò Ò Ò
Heat radiation deficiency
of the outdoor unit
Ò Ò Ò Ô Ô Ô
Inefficient compression
Ò Ô Ô Ò Ô Ô
• Carry out the measurement 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
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.
Insufficient switches of the 4-way valve
• Electric current during operation becomes approximately 80% lower than the normal value.
• 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.