It worked fine all summer until last few months. When I have it to cool it blows air but not cold air. Now that I want heat it blows cool air and not hot air. It took it 30 minutes to heat my 1000SF home from 64 degrees to 65 degrees. What could be the problem?

Split unit, meaning ac unit on the outside and furnace/airhandler on inside,either in basement,in attic,or somewhere in living area like a closet,or utility room. So unless you have a heatpump your heat is being made and blown into the home by the furnace/airhandler, During the summer when you was using the ac the blower inside the furnace/airhandler blew air across the evaporater coil and blew cool air into the house. In colder weather the same blower blows across electric elements that are hot blowing warm air into your home, so either the elements are not working or the relays that are telling the elements to heat up are not working,with a couple of extra safety devices in between that are necessary to be working. The tstat is the control that sends signals to equipment as to what you want it to do and the temp.settings
So with all this said unless you are very savie with test tools and knowhow it would be hard to tell you how to fix without being there., please tell us what you have checked out and anymore questions we might help you with, Please feel free to ask

All this was said guessing you have electric furnace/airhandler,, if you have gas furnace it's a little different but the same procedure

It is electric. This is what I have checked so far. I searched online and saw how to check the tstat to make sure it wasn't that. It isn't that. A friend told me that it sounded like I needed freon added so they knew someone who could add it and last weekend they came and added freon. When we turned on the heater it did blow hot air and I thought great that was it. However a week later it is not working again.

Sounds like 1st of all you have a heatpump, and if they/someone added freon and it again is not working you have a leak, so its time to call out the pro`s because this isn`t an easy do-it-yourself fix,, sorry but its not going to be a cheap fix, but has to be don`t if you want it working,, You probably have a emergancy setting on the tstat that will give you heat from the Aux,furnace only but the expense will be much higher than using the heatpump

Thanks for your help. When you say it is not a cheap fix... can you give me a guesstimate?

Hard to do guesstiments vary state from state, city to city, Cost of materials and labor are not the same
You might call several different local companies and tell them what your probablem is and they might give you guesstiment over the phone


,, Good Luck,, let us know how it comes out