A couple days ago my Suburban furnace decided to quit. After applying my tremendous powers of logic, I came to the conclusion it was the sail switch or something else..

I tried to take the back cover off but it was awfully tight and I didn't want to tempt the 'oh darn' gods so I called a local mobile RV service here in Ogden.

He showed up and after muscling the cover, it finally came off. A quick glance indicated the screws holding the switch were gone.

He wired it back into place and all is well. I will get a couple screws in it after we get home in a cupple weeks.

Glad you fixed your problem, but my concern would be where did those screws go? if they are rolling around someplace could they get caught in the fan?

I thought about that later myself. I will look for them when we return home but they are so small (2-56 or 4-40) I won't get too worried.

If I remember correct the sail switch is down stream from the fan at the out let of the furnace. So hopefully you'll be ok

Need to pull the outside cover of the furnace also but it would not come off. So what was the trick to muscling the cover off?

Take out the 4 screws. Then it is held by the slip fit of the two air tubes. They just pull out so you wiggle it until it breaks free.

Would there be any possibility of some pictures? And.....what the heck is a sail switch?

No pictures but the sail switch is a microswitch mounted at the opening of the air plenum. It has a blade (sail) that catches the air when the fan is on. It then tells the control system the fan is active and allows the gas valve to open and be ignited. Purely a necessary safety switch.

I was surprised at how open the furnace is and how easy it is to service. OBTW, mine is the SF-42 version.

Is the sail switch that you speak of mounted on the outside panel of the furnace (In my case above the hitch in the back of the coach) or is the "air plenum" that you mentioned on the inside of the coach? I am assuming that someday soon my furnace will give up the ghost and it is always nice to be forearmed.

Yes Bill. The furnae on mine is also above the hitch. All components are in that panel and the sail switch is very visable.