I noticed last night the fan from my upstairs unit stayed on continuously. The only way I could get it to turn off was to set it to "cool". I have a heat pump outside for each level and air handlers in the basement and attic. I live in the mid-Atlantic region. I am totally clueless when it comes to these things.

One thought, check the settings on your thermostat. Same have a fan on/ auto setting. On auto, the fan should turn on when the system is calling for heating or cooling. Fan on setting will have the fan run constantly. Hope this is helpful.

I do have that type of thermostat and it is in the auto setting. The only way to get the system to turn off though, is to set to cooling mode. At present I have it turned off. Luckily, I like it cold. My husband also suggested the problem could be with the thermostat.