Originally Posted by lngroller
I have a heat pump with indoor air handler and Emergency back up electric heat. All of a sudden the airhandler fan stopped working. After checking fuses, breaker box etc I tried heat just to see and after the wait period the heat came on and so did the blower. I switched back to A/C and after the wait period the outdoor unit started working but airhandler fan still doesn't come on. I figured if Outdoor unit works and indoor unit works in heat that it would have to be the thermostat. well replaced it today and same thing.
Any ideas? This makes no sense to me if not the thermostat.
Where you activating the emergency heat or the heat pump in heat mode? What if you set the fan mode to 'on' at the stat, does the fan run then? What is the make and model# of the air handler? If it's a multi-speed blower, usually a different speed tap is selected for cool than for heat, so it may be a problem with the jumper that selects the cooling fan speed.