Strange furnace problem

[davidmurphy02]

We are halfway through a two month trip in Utah. We have needed the furnace every night and it has worked flawlessly...almost. Since replacing the sail switch last year the new one has gone through several hundred cycles without a hitch' and I am well acquainted with the click the furnace makes when it gets the "all good" signal from the sail switch and begins ignition.

A week or so ago I awoke during the night and it felt cold...too cold. The temp in the trailer was 52, thermostat showed furnace set on 60 but it was not running. I turned it off and back on again and the furnace kicked in, ignited and ran normally the rest of the night. Ran normally for another week or so, I figured some little electrical glitch but since it was working OK nothing to check out.

Tonight it did it again. I was able to cycle it off and back on and it resumed operation. A few hours later I heard the furnace short-cycle, came on but ran about a minute and quit. Boosted the temp setting until it came on, I heard the sail switch click normally but no ignition and the blower quit after about a minute.

Waited a little while and tried again. Furnace ignited and ran this time so I turned the thermostat up a bunch to heat the trailer as much as possible in case it quit again, we are at Bryce Canyon and low will be in the 20's. Waiting to see now if the furnace will cycle again, but the sun will be up in a couple of hours so we are OK tonight.

Does this sound like a circuit board issue? The failure to ignite seems to point at that, but the intermittent failure has me puzzled. Plenty of propane and all other propane appliances are working fine.

OCD boy scout that I am, I have a spare furnace circuit board and will likely put that in today to se if that eliminates the problem, but want to run this by the group and see if there is anything else I should be checking.