SiUS04-924_A Control Specification
40 Function and Control
3.12 Malfunctions
3.12.1 Sensor Malfunction Detection
Sensor malfunction may occur in the thermistor.
Relating to Thermistor Malfunction
1. Outdoor heat exchanger thermistor
2. Discharge pipe thermistor
3. Radiation fin thermistor
4. Outdoor temperature thermistor
3.12.2 Detection of Overcurrent and Overload
Outline An excessive output current is detected and, the OL temperature is observed to protect the
compressor.
Detail If the OL (compressor head) temperature exceeds 120 ~ 130°C (248 ~ 266°F), the system
shuts down the compressor.
If the inverter current exceeds 20 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 Control
Outline I: Detecting by power consumption
If the power consumption is below the specified value and the frequency is higher than the
specified frequency, it is regarded as refrigerant shortage.
The power consumption is low comparing with that in the normal operation when refrigerant is
insufficient, and refrigerant shortage is detected by checking a power consumption.
II: Detecting by discharge pipe temperature
If the discharge pipe temperature is higher than the target discharge pipe temperature, and the
electronic expansion valve is fully open for more than the specified time, it is regarded as
refrigerant shortage.
Refer to page 105 for detail.
Frequency
Power consumption
Refrigerant shortage zone
(R14459)
40 Hz
(R1391)
Target discharge
pipe temperature
Refrigerant shortage
zone
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