Sail Switch Issue

Willym

Well-known member
I recently had an issue where my furnace would not restart i.e. it would initially run when setting up at a campground, but would not start (the fan would not even run) after the thermostat demanded it on again. On a couple of occasions I wiggled some wires inside the furnace cover and it restarted. I then realized that the wires that I wiggled were attached to the sail switch. I purchased a new switch ($10) and removed the plastic shroud over the fan. The sail switch is attached to the inside of the shroud. The problem was that there was a small piece of styrofoam wedged between the shroud and the sail switch arm. It was causing the switch to stick on, and this killed the furnace. I presume that this is a fail safe design feature. i.e. if the switch is already showing that there is airflow then it would not show a low flow condition. With the styrofoam foreign object removed, the furnace has worked properly since.
 
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