Freeze Prevention Control; Compressor Reverse Rotation Protection Control - Panasonic CS-C18PKF Service Manual

14.5 Freeze Prevention Control


To protect indoor heat exchanger from freezing and to prevent higher volume of refrigerant in liquid form return to
compressor.

This control will activate when temperature of indoor heat exchanger falls below 2°C continuously for more than 4
minutes and compressor turn off.

The current fan speed will change to freeze prevention speed after 70 seconds compressor on. The fan speed
will be increased according to the indoor pipe temperature as below figure: (Applicable for C9KKH and C12KKH
ONLY)

Compressor will restart again when the indoor heat exchanger temperature rises to 10°C (Recovery).

Restart control (Time Delay Safety Control) will be applied in this control if the recovery time is too short.

14.6 Compressor Reverse Rotation Protection Control


If the compressor is operating continuously for 5 minutes or longer and the temperature difference between
intake air and indoor heat exchanger is 2.5°C or less for continuously 2 minutes, compressor will stop and restart
automatically.

Time Delay Safety Control is activated before the compressor restart.
Compressor starts for ≥ 5 minutes
▲T ≤ 2.5°C for 2 minutes
▲ T = Intake air temperature – Indoor heat exchanger temperature

This is to prevent compressor from rotate reversely when there is an instantaneous power failure.

If this condition happens continuously for 5 times within 50 minutes, unit will turn OFF with TIMER LED blinks.

The 5 Times counter can be reset when either one of the following condition happen:
Unit is OFF by remote control or AUTO OFF/ON button.
o
Indoor intake temperature – Indoor piping temperature > 5°C for one minute or more.
o
Operation mode change.
o

The unit could be ON by pressing OFF/ON button at remote control but the TIMER LED will continue blinking.

TIMER LED blinking will be reset if:
Indoor intake temperature – Indoor piping temperature > 5°C for one minute or more.
o
Power supply reset.
o
Indoor Heat
Exchanger
Temperature
(°C)
10
4 min
2
RPM shift
(ID temp) Pipe
+0
6.0°C
+20
4.0°C
+40
2.0°C
+70
73
Recovery
Compressor OFF
7.0°C
5.0°C
3.0°C
Compressor
OFF
Compressor
restart