SiME281906E
Troubleshooting by Error Code
Part 6 Service Diagnosis
174
5.35 Refrigerant Shortage (Error)
Applicable
Models
All outdoor unit models
Error code
U0
Method of Error
Detection
Cooling
Detection based on difference in temperature between temperature preset by remote controller
and suction air temperature, electronic expansion valve opening degree, compressor frequency
and low pressure.
Error Decision
Conditions
Cooling
The conditions below are obtained under a refrigerant shortage warning (
1)
The evaporation temperature remains far below the target evaporation temperature.
The temperature detected with the outdoor heat exchanger middle thermistor (R5T) does
not increase even when operation starts.
The temperature detected with the indoor heat exchanger thermistor (R2T) does not
decrease even when operation starts..
1. In test operation mode, the conditions are obtained even without a refrigerant shortage
warning.
Supposed
Causes
Refrigerant shortage
Defective compressor wiring, compressor open phase
Stop valve is not opened.
Clogged refrigerant piping system
Mismatching of wiring and piping