Panasonic CS-Z25UD3EAW Service Manual page 87

16.3.4 Low Temperature Compressor Oil Return Control

In heating operation, if the outdoor temperature falls below -10°C when compressor starts, the compressor
frequency will be regulated up to 600 seconds.
16.3.5 Cold Draught Prevention Control

When indoor pipe temperature is low, cold draught operation starts where indoor fan speed will be reduced.
16.3.6 Deice Operation

When outdoor pipe temperature and outdoor air temperature is low, deice operation start where indoor fan motor
and outdoor fan motor stop and operation LED blinks.
16.3.7 Low Pressure Protection Control

During low ambient heating operation, if the pipe temperature drops below -24°C, the max frequency will be
reduced and limited.

If it does not rises after 3 minutes, the compressor will stop.

The compressor will start again if the pipe temperature rises above -20°C.
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