Quote:
Originally Posted by Jamric
Tried furnace this morning after getting it to work with bypassing heat limit switch, now the fan just runs and no ignition! Sail switch or what?
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FWIW, I have about 30 years experience in residential HVAC. Much less with RV furnaces. If your ignitor sparks, it's not the sail switch, high limit switch, fuse or many other things. If the ignitor sparks and there's no flame and you're smelling propane out the exhaust, the high probability issue is the ignitor. Take it out and clean it as well as the area the spark strikes. I won't swear to it, but I believe the gap should be about 1/8".
Observe the spark to see if it's a strong or wimpy spark. If wimpy it could be the control board or the cable that that connects the board to the ignitor.
If you get flame that goes out after about 3-4 seconds and the system tries again (usually 3 tries) before locking out, the control board isn't sensing the flame. Clean the ignitor and ground area as above first. If the issue continues with a good flame that surrounds the ignitor, you likely have a failed control board. I don't believe there is a way to test the flame rectification on an RV furnace which is how you'd determine if it's a bad board.