I had a problem about a month ago. I had my thermostat set on 68 heat auto. The temp went over 81 and continued to keep heating. When I got home to find this, I shut it off and replaced the thermostat. I went with a LUX programmable one. Last night I had the a/c on 74 cool auto. It got down to 65 in here and it continued to run. Anyone have any suggestions? Seems kind of strange that a $60 thermostat would be dead in a month, and even more strange that the old thermostat which was a 6 month old honeywell programmable would be doing the same thing. My home warranty company sent out a technician who said it was the thermostat. In reading online I read to disconnect the white wire from the furnace and the fan continued to stay on, it is not the thermostat. When I disconnected all the wires to the thermostat completely, the fan continued to run. It is a 10 year old carrier furnace and air conditioner. I can provide model numbers if necessary. Please help.

Thanks

Sounds like your thermostat is out of order since it controls the temperature. It could also be a stuck control in the furnace but I doupt that. It might be that the thermostat wired incorrectly. I would also recheck your thermostat wiring.