Furnace sail switch

Kenmartin1 wrote:
I have a 96 thor residency 36' motorhome that has been sitting for a few years. Has front and rear furnaces, ignition style atwoods. Upon starting, both furnaces fan's run strong, but wouldn't light. I bypassed the sail switch and both furnaces operate properly. I removed a sail switch and tested it for continuity, and it works! My fans seem to be blowing strong out of all floor vents... Do these switches get stiff or stuck when old???

Thanks, Ken

Sail switches are basically a sensitive microswitch. They do become "flakey" or intermittent before failing completely. A continuity test may indicate they are good, but that isn't the best test. The contacts inside the switch become corroded or dirty, and when operated by hand they will often test good. Using a DMM on a low-ohms scale, you will likely see the resistance of the switch bouncing around from a few ohms to several hundred ohms. If the furnace works fine with the switch bypassed, then replace it.