It is with the heater on a 14 year old system. I can see the heating coils light up and in a few seconds the fan comes on and cools the heater coils then the fan goes off and it repeats this cycle. The outdoor unit does not come on during this process. Used to be able to reset the unit by cutting power and resetting the unit. It would run fine until it was real cold outside. Now when I reset it does not reset. This is a york 10 seer heat pump. I thought about changing out control board but it is really expensive

Inside fan runs all the time. Disconnected green wire and it still runs. Turn thermostat off and fan still runs. Fan switch is in auto position.