Originally Posted by wdperry
I have a 5th wheel Keystone Cougar High Country. Just ran out of propane, and so I filled the two bottles, turned everything back on, and now the furnace will not ignite. It starts, blows cold air then shuts off. Stove burners work well, so I know Im getting propane....Any suggestions as to the possible trouble?
If it runs for 30 seconds on the nose and it's a suburban SF series furnace, odds are the limit switch is at fault.
Typically it either sticks or corrosion on the contacts reduces voltage and then the logic board makes the wrong choice.
Unplugging and reconnecting the terminals often solves the problem for years.
It's easy to test: use a paper clip to jump the two sides of the switch and try to start the furnace. If it starts with the jump and then dies when you remove the jump, it's the limit switch.
Keeps running? Problem is elsewhere.
Look at the sail switch next.
If you are unlucky like many SF series owners, there's no way to get at the guts of these without removal from the coach since many installers had the brains to not install an external service door :-/