i have a Trane XE80 furnace and have had multiple problems since turning it on this month. my current problem is after the house comes to temp and the burners shut off, the fan continues to blow and won't stop. Now it's blowing cold air, it will keep the house at temp but just won't stop blowing. i have tried replacing the digital wall thermostat and that did not fix the problem.
my 1st problem, don't know if it was related, is the burners would come on for about 5 seconds and shut off. it would do this twice then the blowers would come on and just blow cold air. i replaced the flame sensor and that seemed to fix the problem, now i just need to get the fan to stop constently blowing.
I know you posted this question a long time ago, but I'm having the same issue now. Furnace heating up but then won't shut off and turns to cold air. What ended up being your problem? Any help would be great. Thanks!
So the furnace heats, but when it's time for the furnace to cycle down, the burners go OFF, but the blower stays ON?
Are you certain the Fan switch on the thermostat is turned to AUTO?
You can try removing the Green thermostat wire. This controls the fan. If the fan goes OFF after you remove the green wire, then you probably have a bad thermostat, or fault thermostat wiring.
If not, and if this furnace is controlled by a circuit board, then you could just have a bad board. Only way to troubleshoot that would be to have a tech analyze it, or to replace it with a known good board.