Can you tell if the compressor is running on it or does it make any other noise/sound ?
My husband says the unit is humming, but the fan will not run. The furnace part that is located under the house is running
OK, if it s a loud humming noise that would be the compressor running without the fan, which is not what you want , if it s slight hum it could be the contactor pulled in but neither the compressor or fan running, if you could go feel the two copper lines coming out of it and tell me what they feel like I may be able to tell you which one it is doing, let me know.
Ok, you are welcome to reply back to this after he can check it out, other than that it sounds like you have lost high voltage power to it and that the contactor is humming, I will be online most of the day so just reply back if you get more information. If you lose the page you can use this link to get back , in the meantime if you have auxiliary heat you should switch to emergency heat on your thermostat.
I know my husband tried what you suggested and that the fan still did not come on. We live in Georgia and are not used to the super cold we have been having. He did wonder if it was okay for the furnace to be running without the heat pump
It is ok for that to happen, sorry for the confusion with two experts replying , J is new here and still getting familiar with procedures.
It is OK for the furnace to run without the OD unit running. You might switch your thermostat to the "Emergency Heat" setting so the heat pump (OD unit) won't try to come on. That should keep you comfortable until you can get someone to diagnose what's going on with the OD fan.