Rencently is was cool outside and I turned off my air conditioner. A couple of days later I wanted to turn it back on. It no longer blew cold air. Everything appears to be working fine. I turned it off and haven't tried to use it until the other night it was cold out and I wanted to heat the house, I turned on the unit again it won't blow hot air either. The fan works it sounds as if the compressor is coming on. This is a new unit less than two years old. Last winter it kept freezing up on the outside of the unit, the fan wasn't coming on. The repairman replaced what ever was wrong with it 10 months ago. Have any idea what is wrong with it? I have washed off the outside unit, I have changed the filter. I even took of the panel and felt the copper hoses. One gets hot the other cool. Not cold. If this is something that I can repair myself I would much rather do it than have to pay a $75.00 travel charge, $59.00 service charge plus repairs. The compressor is the only thing still under warranty.

Hi,
Frosting up could be a sign of low gas in the system. This is something that a repair person will have to check; and if needed, add more.

OK, this is a heat pump? To get warm or cool air out of it, the compressor and fan outside must run plus the fan in the air handler inside. The control valves must be set for the proper mode and the proper expansion valve must be working. With one tube hot and the other cool, likely the compressor and outside fan are working OK.

When you say it wouldn't blow warm air do you mean it is not blowing, or it blows air, but the air isn't warm? If it is not blowing air at all, likely it is a bad relay. Used to be simple to check and replace, but now most of them are on a circuit board and tough for DIY repairs. A new board is expensive. You need to have a lot of confidence in your diagnose before spending that much money.

I don't know if heat pumps have the limit switch that keeps the fan from starting until the air is warm or not. If so, it would be a little box near the inside coil with a couple of wires running back to the circuit board. I think it should be closed when the coil is warm. There may be a second one to shut the unit down if it over heats. There may be a schematic inside to help you locate the limit switches. If you identify the low limit switch, and decide it is bad, replacing it would be a simple, cheap fix. Otherwise, it is gamble on a new circuit board, or call the tech.