Troubleshooting SiMT041311E167 Service Diagnosis2.33 Refrigerant ShortageError Code U0Method of ErrorDetectionRefrigerant shortage detection I:Refrigerant shortage is detected by checking the input current value and the compressorrunning frequency. If the refrigerant is short, the input current is lower than the normal value.Refrigerant shortage detection II:Refrigerant shortage is detected by checking the discharge pipe temperature and the opening ofthe electronic expansion valve. If the refrigerant is short, the discharge pipe temperature tendsto rise.Refrigerant shortage detection III:Refrigerant shortage is detected by checking the difference between suction and dischargetemperature.Error DecisionConditionsRefrigerant shortage detection I:The following conditions continue for 7 minutes. Input current × input voltage ≤ A × output frequency + B Output frequency > CRefrigerant shortage detection II:The following conditions continue for 80 seconds. Opening of the electronic expansion valve ≥ D Discharge pipe temperature > E × target discharge pipe temperature + FRefrigerant shortage detection III:When the difference of the temperature is smaller than G°C, it is regarded as refrigerantshortage. If the error repeats, the system is shut down. Reset condition: Continuous run for about 60 minutes without any other errorSupposedCauses Disconnection of the discharge pipe thermistor, indoor or outdoor heat exchanger thermistor,room or outdoor temperature thermistor Closed stop valve Refrigerant shortage (refrigerant leakage) Defective electronic expansion valve Refrigerant drift in the outdoor heat exchanger Poor compression performance of compressorA (–) B (W) C (Hz)2800/256 –350 55D (pulse) E (–) F (°C)470 128/128 20Operationmode Description G (°C)Cooling room thermistor temperature – indoor heat exchanger temperature 4.0outdoor heat exchanger temperature – outdoor temperature 4.0Heating indoor heat exchanger temperature – room thermistor temperature 4.0outdoor temperature – outdoor heat exchanger temperature 4.0
