Daikin BPMK928B42, Service Manual

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Si18-201 Troubleshooting - Outdoor Unit Related
Service Diagnosis 295
3.3.31 Operation Halt Due to Detection of Gas Shortage
Outdoor Unit
Indication
U0
Method of
Malfunction
Detection Detection Method 1
Lack of gas is detected using the input current detected by the CT and the compressor's
operating frequency.
Detection Method 2
Lack of gas is detected using the discharge pipe temperature and the motorized valve opening.
Malfunction
Decision
Conditions Detection Method 1
Input current < 0.09 × Compressor's operating frequency -3.5
However, when the above state continued for 7 minutes with the operating frequency > 55(Hz)
Detection Method 2
discharge pipe temperature >Target discharge pipe tempe20°C, that should be
continued for 80 seconds or longer with motorized valve full opening.
Note: The target discharge pipe temperature is calculated with the microcomputer.
Supposed
Causes
"
Gas shortage due to refrigerant leak
"
Faulty gas shortage sensor
"
Input current drop due to faulty compression of the compressor
∗
Disconnection of thermistor (all thermistors)
∗
Faulty CT
"
Faulty, Disconnected motorized valve
"
Incorrect wiring, piping