We have a 6 year old Trane XR90 furnace that runs on propone. When the furnace starts in the morning, it blows cold air. We manually shut the furnace off with the thermostat, wait for the fan to stop (10 - 15 minutes) then restart and we have heat. If we manually stop/start without waiting for the fan to stop, we continue to get cold air. Works fine for the rest of the day. This has happened 2 days in a row now. The problem started one month ago but was intermittant at that time. The first time it happened was when the unit was started for the first time in the season. Our thermostat is a programable unit.
Anyone know what the problem might be? It is related to the thermostat or the heating unit itself?