SiUS121502E Control SpecificationFunction and Control 773.14 Malfunctions3.14.1 Sensor Malfunction DetectionSensor malfunction may occur either in the thermistor or current transformer (CT) system.Relating to Thermistor Malfunction1. Outdoor heat exchanger thermistor2. Discharge pipe thermistor3. Radiation fin thermistor4. Gas pipe thermistor5. Outdoor temperature thermistor6. Liquid pipe thermistorRelating to CT MalfunctionRefer to CT or related abnormality on page 158 for detail.3.14.2 Detection of Overcurrent and OverloadOutline In order to protect the inverter, an excessive output current is detected and the OL temperature isobserved to protect the compressor.Detail If the inverter current exceeds 13.0 ~ 18.5 A (depending on the model), the system shuts downthe compressor. If the OL (compressor head) temperature exceeds 130°C (266°F), the compressor stops.3.14.3 Refrigerant Shortage ControlOutline If the power consumption is below the specified value and the frequency is higher than thespecified frequency, it is regarded as refrigerant shortage.The power consumption is low comparing with that in the normal operation when refrigerant isinsufficient, and refrigerant shortage is detected by checking power consumption.Refer to Refrigerant shortage on page 136 for detail.3.14.4 Anti-icing FunctionDuring cooling, if the indoor heat exchanger temperature in the operation stopped room dropsbelow the specified temperature for a specified time, the electronic expansion valve is opened inthe operation stopped room as specified, and the fully closed operation is carried out. After this, iffreezing abnormality occurs longer than a specified time, the system is shut down.FrequencyRefrigerant shortage zone(R21927)40 ~ 54 Hz(depending onthe model)Power consumption(Input current)
