A few points that may clear some doubts? One is that I don't do hard repairs until I know for pretty sure that I have to do the ahrd stuff!
First thought is that we often dan do a better job if we get the best info we can. On that, have you looked for a guide for the specific furnace you have? There are lots of different brands and models, so knowing what you have is often a good step to knowing what holds it in place or if it is really necessary to pull it!
Mots of us won't know which exact brand and model that RV has instaloled, so can't give very good suggestions.
But on a more direct line, if we knew where the connections would be found, I would want to test the sail switch before going to the trouble of getting it pulled out!
I might guess that the wires going to the switch might connect onto the board, etc. on the fron of the furnace? Bit of guessing without kjnowing which furnace, but if those wires are handy to get at, I would certainly want to test the switch before working too hard to get to the switch itself.
One way to do the test is , find the two wires, connect a ohmemter between the two wires with them off any board, etc. and see it it opens and closes continuity as the fan blows and it should close.
Most I have worked on will show and open when tested and then when the sail moves, there should be a path from one wire tot he other, indicating the switch has moved ot close the contacts. Simple on/off type micro switch and all you are looking for is it oppening and closing the path?
Test is simple but maybe a more direct question will help? Do you have two vents on the outside of the furnace and RV? One to let air into the combustion chamber where the fuel burns and the other to let that air pass on out? That is where the air has to blow the sail switch to confirm air takes fumes out beofrwe they let the gas valve open!
So is there some form of screen over the vents to eep things like mud daubers from getting into that perfect looking hole and building a nest on this handy thing hanging down inside? Not at all uncommon for this to happen if the RV is stored without screens to keep them out of the vents!
If you have a good sized vacuum to blow and suck air through that vent system, it may show it to be stopped up with a wasp nest. At that point, I move to trying to break the nest off to get it out! But do be aware that you don't want to get so rough that you also hang a wire on the sail and pull it off! Bang around enough to knock a mud dauber nest off but not knock the sail switch out???
Small point to know? The sail is normally in the vent that lets fresh air in, as that keeps it out of the hot air after the burner. If that idea is correct and you find the switch is not opening/closing, try finding which vent is intake and check that one first as it is often a semi-short distance in from the vent to the sail!
Sorry about the long post but this does tend to be a frequent problem after storage and getting screens on is often not thought of in time! If you hapen to have one of the little camera probes to fit cell phones, they can be handy to run in that vent to take a look?
