Sail switch follow-up

[davidmurphy02]

We picked up our trailer last spring. In two major trips, the furnace was fine for the first night or two of cold weather but then the sail switch crapped out. I had purchased a spare after hearing about a number of others who had sail switch problems, and the first time it quit I replaced it. The replacement switch worked fine for the rest of the trip, but when we got home I blew out the original switch thoroughly with compressed air and reinstalled it.

After cleaning, the original switch worked fine....for another day or two. The second time it gave up I replaced it. We just got home from a 19 day trip to west Texas, some very cold nights (many below freezing, lowest was 16). The furnace ran like a champ - cycled often on really cold nights but worked perfectly. It took me a while to trust the new sail switch - I found myself counting each time the blower came on and listening after 15 seconds for the sound of the burner igniting, indicating that all was well with the sail switch.

I am pretty convinced that the issue with the sail switch is not lint, as many originally thought. The contacts are not exposed - there is a little plastic plunger that the sail operates and the contacts are down inside the switch. It would take a lot of lint to physically keep the switch from operating, and with no intake filtration I'm sure a certain amount of lint gets into all RV furnaces. Instead, I think that the issue is a "bad batch" of sail switches, or perhaps just a poorly manufactured switch with a high failure rate. I haven't heard much in the way of sail switch problems lately, seems like it was much more of an issue a year ago - which makes me lean towards the "bad batch" explanation.

At any rate, based on my own experience if you have a sail switch problem I'd recommend just tossing out the failed switch rather than cleaning and reinstalling it, and then of course hoping that your replacement switch is a good one. I now carry two spares

[Bill and Earline]

I agree wholeheartedly, David.

My furnace exhibited sail switch problems inconsistently, so I pulled the furnace. That's not too easy to do on the "classic" models that must be done from inside the trailer. I tested the continuity on the switch and it seemed fine after being jostled, so I put it back in, saving my new replacement.

Luckily I didn't put it all back together before testing a few times. Again it worked some of the times, but not always. I replaced the switch and have had no problems, but I do carry yet another replacement. That umbrella will keep it from raining.

[HABBERDABBER]

I've done a quick search without finding the info.


What is the sail switch model # and where can one be obtained?


Thanks,

[Perry Butler]

Originally Posted by davidmurphy02

After cleaning, the original switch worked fine....for another day or two. The second time it gave up I replaced it. We just got home from a 19 day trip to west Texas, some very cold nights (many below freezing, lowest was 16). The furnace ran like a champ - cycled often on really cold nights but worked perfectly. It took me a while to trust the new sail switch - I found myself counting each time the blower came on and listening after 15 seconds for the sound of the burner igniting, indicating that all was well with the sail switch.

I am pretty convinced that the issue with the sail switch is not lint, as many originally thought. The contacts are not exposed - there is a little plastic plunger that the sail operates and the contacts are down inside the switch. It would take a lot of lint to physically keep the switch from operating, and with no intake filtration I'm sure a certain amount of lint gets into all RV furnaces. Instead, I think that the issue is a "bad batch" of sail switches, or perhaps just a poorly manufactured switch with a high failure rate. I haven't heard much in the way of sail switch problems lately, seems like it was much more of an issue a year ago - which makes me lean towards the "bad batch" explanation.

At any rate, based on my own experience if you have a sail switch problem I'd recommend just tossing out the failed switch rather than cleaning and reinstalling it, and then of course hoping that your replacement switch is a good one. I now carry two spares

In the first 90 nights our sail switch failed at least five times. I got pretty good at removing/cleaning/reinstalling that switch.

After much arguing we finally got a free replacement under warranty. Nearly 250 nights later I've yet to clean the switch. Two nights I was cleaning that original switch in less than 20 F, under the stars. However, about a third of our nights we use a Martin catalytic heater that we purchased because of the sail switch problems.

We also have two, new sail switches ready for installation, but Murphy's Law says we probably won't ever use them.

Enjoy,

Perry

[davidmurphy02]

Originally Posted by HABBERDABBER

I've done a quick search without finding the info.


What is the sail switch model # and where can one be obtained?


Thanks,

The sail switch part number is 33081. Here is one source:

https://pdxrvwholesale.com/products/...-bracket-33081

[rubicon327]

Originally Posted by davidmurphy02

The sail switch part number is 33081. Here is one source:

https://pdxrvwholesale.com/products/...-bracket-33081

In an effort to avoid some confusion if one searches the DFSAD12 (originally AFSAD12 before Atwood was purchased by Dometic) furnace model on edometic.com they will see a sail switch part #33063 which is discontinued. The replacement depends on your furnace serial number - it could be 33081 (newer - after S/N 72498929) or 31093 (older - before S/N 72498929). Not sure where all the Escape furnaces stand in relation to the S/N sequence.

[Also for owners with the older Atwood 8012-II Everest Star furnace your sail switch is 36134]

[Bill and Earline]

Originally Posted by HABBERDABBER

I've done a quick search without finding the info.


What is the sail switch model # and where can one be obtained?


Thanks,

The first order of business is to verify the Atwood model. I found a 2 year old post where I replaced mine. Model of my furnace with trailer purchased in late 2014 is 8012-II and sail switch I have in reserve is 36134. That part number is hard to locate, but I still found one today. There may be a cross-over to a new number, but I didn't look for that.

[Mike Lewis]

Another recent thread on the furnace indicates that weak airflow may be keeping the sail switch from tripping:


https://www.escapeforum.org/forums/f...ues-19603.html

[HABBERDABBER]

My furnace is an AFSAD12, as noted on the closet Escape sticker appliance sheet.
I have removed the exterior grill and find no tags for model ID. Any ideas here where model info can be?
Rig is 2016 classic, delivered mid-year.

[rubicon327]

Originally Posted by HABBERDABBER

My furnace is an AFSAD12, as noted on the closet Escape sticker appliance sheet. I have removed the exterior grill and find no tags for model ID. Any ideas here where model info can be?
Rig is 2016 classic, delivered mid-year.

What do you mean by exterior grille? The supply grille inside the trailer? The S/N should be on the fan housing at the rear of the furnace. If you don’t have the exterior access hatch I believe you unfortunately need to pull the furnace to access. See pic.

[HABBERDABBER]

Thank you for the photo and info. I meant the cabin grill cover. No external hatch on my rig.

[jking1224]

I have some feedback on this issue as well.
I believe at least part of the problem is that the sail switch is blocked by the furnace enclosure. That is, the “wing” and arm hit the sidewall of the sheet metal and the switch fails to close.

When my furnace failed, I of course had to dismantle it. Being a 2017, I did not have the external access door, so this is a painful process.

My testing showed the switch itself to be OK. That is, open and close action gave the correct ohm meter short/open behavior. I didn’t have much lint build up, so that got me puzzled. And, of course, trying to identify and buy the correct replacement was a challenge. That is, I ordered what I thought was the correct switch, but when it arrives it is physically different.

So, at that point, I am challenged to figure out why a tested good switch will not make the furnace work and an exact replacement is hard to come by.

So, I actually look inside the furnace.

It turns out in my furnace model with the factory switch, the small “sail” and arm assembly bang into the sidewall of the sheet metal enclosure quite easily. That is, there is NOT sufficient room for the switch to freely swing back and forth, full range of motion. So, while the fan comes on and wind is blowing, the sail itself moves, but not far enough to trigger the switch. Of course, this movement can be hindered by lint, hence the common recommendation to clean the lint.

This very tenuous physical arrangement inside explains to me why some people have no problem at all and some folks seemingly have repeated switch failures and constant problems. The problem is not the electrical switch itself, but the sail arm assembly doesn’t have enough room in there to move back and forth. It is a space constraint design problem by Suburban. And Escape has taken to installing an access door to address it and we all endlessly discuss it and troubleshoot the problem.

But the bottom line for me, was to bend and twist the sail arm to allow greater range of motion. It is a process of trial and error. But if you tweak the sail arm a bit and watch the movement as the furnace activates, you may be able to completely solve the problem and not have to be concerned with lint build up for long periods of time.

[Eggscape]

Very good observation...something to be checked.

[rubicon327]

Originally Posted by jking1224

It is a space constraint design problem by Suburban. And Escape has taken to installing an access door to address it and we all endlessly discuss it and troubleshoot the problem.

Great info. One minor clarification though...the furnace was originally made by Atwood and then Dometic bought them. The furnaces were sold as the AFSAD12 model (first "A" presumably for Atwood) and now they are sold as the DFSAD12 (first "D" presumably for Dometic).

I wonder if the discontinued sail switch model number that I posted above and the new replacements based on serial number have something to do with an attempt by Atwood/Dometic to address the issue you are referring to.

[jking1224]

I see in the other thread linked above, some folks mention the ducting as contributing. This would also be consistent with my observation. Any decrease in airflow, regardless of whether it is restricted output or restricted input, might cause the sail switch to not move the full range of motion required to close the electrical contact.

As I recall, my sail switch is an elongated rectangle piece. And the space it occupies is the round sheet metal surrounding the squirrel cage style fan. So, this rectangle is expected to move freely inside a tight circular space.

So, in addition to bending the arm slightly, as well as “twisting” the arm, it might also be prudent to trim the flat sail section with tinsnips. Perhaps round off the corners to better match the round space it is expected to move inside of.

It is unfortunate that Atwood/Dometic has this poor design that the entirety of keeping warm is dependent upon this small tolerance of a “square peg fitting into a round hole”.

[Mike Lewis]

Originally Posted by jking1224

So, in addition to bending the arm slightly, as well as “twisting” the arm, it might also be prudent to trim the flat sail section with tinsnips. Perhaps round off the corners to better match the round space it is expected to move inside of.

When I first ran into this problem I discovered that the sail switch for this furnace is different from ones for other, larger RV furnaces: in short, it has a bigger "sail", I guess to better catch the weaker airflow that the smaller fan produces. So trimming the "sail" might make it stop working. Take care.

[canakiwi]

After endless problems and three new switches, I gave up and took the trailer to a local rv tech. He "fixed" the problem exactly as John describes, including trimming the corners of the sail. since then no problems at all.

[Kat&Penney]

We had our sail switch fail twice on our 20,000 mile trip...and of course it happened at 2 am! My wonderful honey would bundle up and go clean it and put it back together again.

I have ordered two new ones and hopefully we can find other warmer ways to spend our 2 am moments!

Thanks for posting this.

[WRGooding]

At first I found that by hitting the exterior furnace cover with my hand, the switch would free up. After doing this too many times, I slightly bent the arm on the switch, as suggested here in, no more problems. If you look at the small area the sail has to work in, and think of the trailer bouncing down the road, you will also question the engineering design.

When reinstalling the switch make sure it moves easy. The installation process may bend up the arm.