SiBE041012_B
Control Specification
Function and Control
57
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°C, the system shuts down the
compressor.
If the inverter current exceeds 9.25 ~ 20 A (depending on the model), the system shuts down
the compressor.
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 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.
III: Detecting by the difference of temperature
If the difference between suction and discharge temperature is smaller than the specified value,
it is regarded as refrigerant shortage.
Refer to page 75 for detail.
Frequency
Power consumption
(Input current)
Refrigerant shortage zone
55 Hz
(R18342)
(R1391)
Target discharge
pipe temperature
Refrigerant shortage
zone
