Control Specification SiUS04111148 Function and Control3.12 Malfunctions3.12.1 Sensor Malfunction DetectionSensor malfunction may occur in the thermistor.Relating to Thermistor Malfunction1. Outdoor heat exchanger thermistor2. Discharge pipe thermistor3. Radiation fin thermistor4. Outdoor temperature thermistor3.12.2 Detection of Overcurrent and OverloadOutline An excessive output current is detected and, the OL temperature is observed to protect thecompressor.Detail If the OL (compressor head) temperature exceeds 120 ~ 130°C (248 ~ 266°F), the systemshuts down the compressor. If the inverter current exceeds about 15 A, the system shuts down the compressor.The upper limit of the current decreases when the outdoor temperature exceeds a certain level.3.12.3 Refrigerant Shortage ControlOutline I: Detecting by power consumptionIf 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 a power consumption.II: Detecting by discharge pipe temperatureIf the discharge pipe temperature is higher than the target discharge pipe temperature, and theelectronic expansion valve is fully open for more than the specified time, it is regarded asrefrigerant shortage.III Detecting by the difference of temperatureIf the difference between suction and discharge temperature is smaller than the specified value, it isregarded as refrigerant shortage.Refer to page 112 for detail.FrequencyPower consumption Refrigerant shortage zone(R14668)50 ~ 54 Hz(depending onthe model)(R1391)Target dischargepipe temperatureRefrigerant shortagezone
