What normally brings a heat-pump defrost cycle? Is it temp, time, pressure?
Depends on the unit. Some are time/temp; others are demand defrost so it happens when needed.
Normally a set timer initiates defrost if the sensor is closed meaning the line is frozen typically 90 minutes on the timer.
I'm glad this question was asked. I have an Infinity 16 heat pump. Anyone know if it is "on demand"?