Originally Posted By: cbottger
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On most older type heat pumps the defrost cycle is generated by a temperature sensor embedded within the coils of the condenser and is not feasible to check within the scope of a normal HI as the ice would have to build up on the condenser thick enough to generate a defrost or you would have to emerge the sensor in a liquid colder than the factory setting.
I disclaim the defrost sensor only but I do check for proper operation of the reversing valve as the reversing valve is the main item for concern on a standard heat pump. Back before the days of the EPA we could hit the defrost sensor with a little R-22 and send the unit into defrost but those days are long gone. (HOLE in the ozone)
As following the standards of practice for an HI we have no means to manually check the operation of the defrost sensor be it temperature activated or time activated.
My biggest concern for a heat pump is did the installing contractor wire the supplemental electrical heat strips to activate at the same time as the compressor is activated. I am not stating that this is wrong but just not economical as I prefer to have the heat strips activated from the 2nd stage of a 2 stage thermostat and will inform my client as to the wiring set up for the unit.
Don’t argue with an idiot someone watching may not be able to tell the difference.