On cooling, fan runs for about a day then stops. Leave system off for 1-2 days, try again, works again for another day. Thermostat was changed, still same issue. What may be the issue?
Is the compressor also running? Is the system cooling?
If the compressor stops but the condenser fan motor keeps running your heat pump could be equipped with a relay that is causing the problem.
System cools but just for a day or two. Unfortunately the system usually stops sometime during the night. Both compressor and fan not working. We turn the thermostat off. Try a few hours later. Nothing. We try a day or 2 later, it works.
Does the indoor fan only run when the cooling starts? If so, is it still running when the AC stops working, during a call for colling?
No the indoor fan still runs.
Would have to know more details, but, it could be as simple as a weak capacitor, or even contactor.
Yes, my bet would be a bad contactor.
Replace both to avoid the call back.A lit of capacitors this year in GTa area maybe of the longer run time.
If you are in AC mode and the fan was not turning its not a defrost issue and is some sort of fan problem. Have you tried giving the fan a push with a stick? If this starts it normally I would say it was a bad start cap, but since you have already checked that I suppose it could also point to a bad winding on the fan motor. If the stick trick doesn't yield any results your looking at no power at the fan and that could be anything from a loose connection to a bad fan relay.