The radiant fins that surround my heat pump behind the exterior wire mesh guard are all crusted up with an icy frost coating. Heat pumps seems to work OK, but I am concerned. Is this normal? Heat pump is a 2 year old York unit.
This happened to us within the first year we had our heat pump - turned out the air filter was very dirty. Once we replaced it (and continue to replace it regularly) the problem ceased. Worth checking before making an expensive service call.
It is not unusual to get a frost buildup. Most units are supposed to detect when a sizable build-up occurs. When that happens, the heat pump is supposed to reverse itself, that is go into air conditioning mode, releasing heat to the outside rather than pulling heat in.
(Our sensor went bad and we wound up with a huge block ice – we defrosted it but turning the thermostat to cooling and putting a heater underneath it – kept the a/c running while the outside temperature was thirty!).
I have a heat pump(Carrier), and as mentioned it defrosts itself. Sounds like the controls, not the thermostat, are messed up. Call your service tech.