I need some help figuring out what is wrong with my A/C unit. During the summer I had problems with the unit not cooling. I had a service technician come out and he found that the unit was low on refrigerant. He charged the system and it worked fine.

Recently I am having the problem that the unit does not turn off when it reaches the desired temperature. If I set it to cool at 76 degrees when it reaches that temperature it does not shut off and the air coming out of the vents is starts coming out warm . When I manually change the thermostat to off, sometimes it turns off sometimes it doesn't. We recently started seeing some cold days in the south and I switched to the to heat and it does the same thing.

What I end up doing is turning the unit off at the circuit breaker. Sometimes this sort of resets the unit and it works fine for a couple of days but eventually it gets "stuck" again.

I mentioned this to an HVAC store and they mentioned that the relay on the inside unit might be getting stuck.

Any help would be greatly appreciated.

It is possible you have a defective relay which will give the symptoms you describe. Look on the drawing that should be on the blower door and see if there is a blower relay listed. If so I would get a replacement. Make sure you mark any mires before removal. Also turn off the electric power before servicing.

I was also a bit confused on your post. Does the outside unit keep running also? You mentioned that in the beginning of your post. I would also like to ad that is the serviceman did not fix the leak before he added refrigerant the problem will come back.