Every fall I need to relight the pilot light on my Trane Forced Air Gas Fired furnace. I can get the pilot light lit and the fan to come on - the burners ignite and then after a minute or two they shut off and the pilot light goes out. When I checked the thermostat I have it set to heat and 80 just to make sure it will stay on - there is a message now that says 80 -AC which I haven't noticed before - any help? :confused:

You might need a battery for the thermostat. Try that first and report back.