I have a Coleman 7900 Series LP gas furnace in a 1988 mobile home that is used as a weekend cottage. During the winter, the furnace works fine when we are in the home and the thermostat is set to 68. When we leave, the thermostast is lowered to 45. When we return 1 to 2 weeks later, the furnace is not operating and the upper limit switch has tripped. I reset the switch and set the thermostat to 68 and the furnace works fine. This has happened 3 or 4 times. My first guess would be to replace the switch but I'm hesitant because I haven't been there to witness the switch tripping and I'm concerned something else may be wrong with the furnace and that the switch is just doing it's job. It doesn't make sense that the switch should just trip on its own just because the temperature is lower.

Anybody got any other suggestions or should I just change the switch?

Thanks!