SiUS12-928_B
Control Specification
Function and Control
68
3.13 Malfunctions
3.13.1 Sensor Malfunction Detection
Sensor malfunction may occur either in the thermistor or current transformer (CT) system.
Relating to Thermistor Malfunction
1. Outdoor heat exchanger thermistor
2. Discharge pipe thermistor
3. Radiation fin thermistor
4. Gas pipe thermistor for each room
5. Outdoor temperature thermistor
6. Liquid pipe thermistor
Relating to CT Malfunction
Refer to “CT or related abnormality” on page 179 for detail.
3.13.2 Detection of Overcurrent and Overload
Outline
In order to protect the inverter, an excessive output current is detected and the OL temperature is
observed to protect the compressor.
Detail
If the inverter current exceeds 17 ~ 20 A (depending on the model), the system shuts down the
compressor.
If the OL (compressor head) temperature exceeds 266°F (130°C) , the compressor stops.
3.13.3 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 power consumption.
II : Detecting by discharge pipe temperature
If the discharge pipe temperature is higher than the target discharge pipe temperature, and the
outdoor electronic expansion valve is fully open for more than the specified time, it is regarded as
refrigerant shortage.
Refer to “Refrigerant shortage” on page 156 for detail.
Frequency
Power consumption
Refrigerant shortage zone
(R11685)
40 ~ 55 Hz
(depending on
the model)
(R1391)
Refrigerant shortage
zone
Target discharge
pipe temperature
