[dlscott185]

In my experience, the fan speed setting on the thermostat needs to be on either high or low. If on auto, it will stop the fan first when it changes fan speed.

I am also under impression that if it detects the condenser/evaporater outside has frozen up, it will reverse itself for a short time so it can pump heat outside to thaw it. Maybe this is happening.

Also, as I stated, it will revert to furnace when it can’t hit the set temp. And your dealer is incorrect about the heat pump heating the belly. There is no way for it to get heat into the belly from the overhead ducts.