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For correct operation of the unit with different outside temperatures, the microprocessor controls the fan speed
based on the pressure reading from the pressure probe, thus enabling heat exchange to be increased and/or
decreased, maintaining the condensing or evaporation temperature practically constant.
The fan functions independently of the compressor.
18.2 Fan speed control
High pressure over low in cooling
1.Pd-tempt is the high pressure modification value at different low pressure saturation temperatures
2.Up/down 1 unit fan motor speed level every 20s
3.Pd_t <=Pd-Tempt+1, when last for 5 minutes the system will report the fault " high pressure over low"
Pd_t (°C)
Pd-Tempt +6
"
A area
"
Pd_t
＜
Pd-Tempt+6
Operate at the lowest fan speed (fan speed No.1) and last for 1 minute, OFF
"
B area
"
Pd-Tempt+6≤Pd_t
＜
Pd-Tempt+10
Reduce the fan speed 1 level every 20s (until to the lowest level)
"
C area
"
Pd-Tempt+10≤Pd_t
＜
Pd-Tempt+12
Keep currnet speed
"
D area
"
Pd-Tempt+12≤Pd_t
＜
Pd-Tempt+25
Increase the fan speed 1 level every 20s
"
E area
"
Pd_t≥Pd-Tempt+25 or Pd≥3.2MPa
Increase to the highest fan speed immediately from D area
Pd-Tempt+10
Pd-Tempt+12
Pd-Tempt+25
or Pd≥3.2Mpa
