Defrosting operation is controlled by the temperature of outdoor heat exchanger sensed by the thermistor and •
the timer switch.
Defrosting operation starts when the both of the following conditions are met at the same time. •
a)35 minutes’ of continuous run of the compressor after the start of heating operation or after the completion of
previous defrosting operation.
b)The temperature of the outdoor heat exchanger stays lower than -1.5°C continuously for two minutes.
Defrosting operating is called o if either of the following conditions is met. •
a)The temperature of outdoor heat exchanger rises to 19°C while 4-way-valve is ON.
b)12 minutes has passed since compressor turned ON.
Working condition of frost protection heater for expansion vessel •
The heater turns ON if the outdoor temperature keeps below 3 degree for 1 minute.
The heater turns OFF if the outdoor temperature keeps above 5 degree for 1 minute.