Service manual

51
8-4 LOW AMBIENT FAN SPEED CONTROL < FOR AER518SCL3 >
●
This function protects the compressor from being damaged due to flowback of the liquid refrigerant to the
compressor when the outdoor temperature is very low.
●
When the air temp. thermistor (TH4) on the outdoor units detects a change in temperature, the solid state relay
(SSR) inside the electrical component box activates to control the fan speed accordingly.
●
As the outdoor temperature decreases and drops below 28.0°C, the outdoor fan speed starts to gradually slow
down following an oblique line as in the diagram below.
●
Outdoor fan speed changes more or less according to the room temperature.
●
When the outdoor temperature goes above 30.0°C, this fan speed control does not work.
Conditions: Room temperature 19.4°C DB/13.9°C WB
800
1000
600
400
200
0
–10 –5 0 5 10 15 20 25 30 35
28.0
30.0
900 rpm
(HIGH)
Outdoor ambient temperature (°C)
Outdoor fan speed (rpm)
Coil temp.
thermistor
(TH3)
Air temp.
thermistor (TH4)