Furnace, Sail switch

[ddcwilson]

Hello group, I have a new 2020 Montana 3120RL and I believe that Sail switch is out. I am a full timer currently living at a RV park in Scotts Valley CA..and I don't have a two gig yet, so moving it will be expensive. Has anyone replaced the Sail switch on their own. If I do the work myself or call in a model Tech does that void the warranty? Any help would be greatly appropriated, its cold! LOL

Dave And Cindy Wilson

[66joej]

Hello group, I have a new 2020 Montana 3120RL and I believe that Sail switch is out. I am a full timer currently living at a RV park in Scotts Valley CA..and I don't have a two gig yet, so moving it will be expensive. Has anyone replaced the Sail switch on their own. If I do the work myself or call in a model Tech does that void the warranty? Any help would be greatly appropriated, its cold! LOL

Dave And Cindy Wilson

Call mobile RV Techs in your area. Some of them are authorized Dometic/Atwood repair depots. Had ours go out also.
There is a 2 year warranty on the furnace. Not a big job if you can find a switch locally.

[ddcwilson]

Thank you for your input!!

[chuckster57]

How did you determine the sail switch is bad? It isn’t very common for it to fail.

[ddcwilson]

I am guessing that is what the problem is. From what I have read if the switch is bad the furnace will turn on and turn off within minutes, which is what it is doing, and from the comments I have read in this forum the sail switch is probably the cause of my problem. I also called Keystone and after I informed them of what the furnace was doing, they listed it as a Sail switch problem.

[ChuckS]

When you say “Turns On” do you mean blower comes on and runs for about 45 seconds and the turns off without getting any heat?

[ddcwilson]

When I say comes on .....the blower turns on and then the furnace ignites blows warm air for a minute or so then turns off......then after a few minutes it repeats the possess.

[Northofu1]

If it starts to heat, I don't think it's the sail switch. If the sail switch is not working the furnace doesn't heat at all.

[66joej]

If it starts to heat, I don't think it's the sail switch. If the sail switch is not working the furnace doesn't heat at all.

^This is true. The sail switch sends a signal current to the gas valve and ignitor.

[ddcwilson]

I am basing my opinion of what is wrong from forum conversations I've read here and from what the factory told me was probably the problem based on my description of what the furnace was doing......if its not the sail switch so be it. I still need a model tech regardless.

And from what I've read here on this forum replacing the sail switch is a common issue......and it was the first thing the factory rep mentioned. Personally I don't care if it is or it isn't, I just want it fixed..... :)

[ddcwilson]

And thank you for your responses! I do appropriate your advice.:)

[chuckster57]

Based on what I’m reading, if it lights and goes out, my guess would be either the igniter/flame sensor or the the control board.

You do need it fixed, that’s for sure and a mobile tech should be able to diagnose it fairly quickly.

[ChuckS]

Since the furnace is firing up then shutting down .. and blows hot air for a minute there is another item in the circuit called the “Hi Limit” switch... it’s normally always CLOSED and designed to open up at a set temp to prevent overheating of the furnace.

It may be out of tolerance. It’s a new unit and all under warranty. A good mobile RV Tech should be able to diagnose the issue and have parts on board to repair your unit.

[flybouy]

Along the high limit switch thought. Check the floor registers for any obstructions. An area rug over a register can block enough air flow to trigger the high limit.

[rjsurfer]

Bad control board.

Ron W.

[sourdough]

It could be the sail switch but the chances are just as good that it's the control board. I've had one fail that did similar things.

[JRTJH]

The only way the furnace will ignite (produce any heat) is if the sail switch is operational. It must close, to confirm airflow through the furnace before any signal can be sent to the gas control valve to open or to the ignition circuit to produce a spark to ignite the gas at the burner.

So, chances are good that it's not the sail switch, but rather the control board (flame sensor or high limit sensing circuit).

Essentially, if the sail switch "moves to close the contacts" when airflow is detected, as long as that airflow remains constant, the sail switch shouldn't "open against the airflow" so I'd suspect it's working normally and is not the problem.

ADDED: That said, if the battery is low, there may be a condition where when the furnace calls for heat, the battery can provide enough voltage to power up the furnace, then after 30 seconds to a minute, the voltage drops down to a level that won't maintain the furnace motor speed and the sail switch closes, not because it's faulty, but because the battery in the trailer can't provide enough power to maintain the fan motor speed. That's NOT a sail switch problem, rather a trailer power problem.

[sonofcy]

Hello group, I have a new 2020 Montana 3120RL and I believe that Sail switch is out. I am a full timer currently living at a RV park in Scotts Valley CA..and I don't have a two gig yet, so moving it will be expensive. Has anyone replaced the Sail switch on their own. If I do the work myself or call in a model Tech does that void the warranty? Any help would be greatly appropriated, its cold! LOL

Dave And Cindy Wilson

I have taken mine out several times, it's easy on my model of furnace. Post a pic of your furnace with the outside cover off and I will check it.

BTW, how do you know it is bad?

[sonofcy]

It's most likely the board, get a replacement on amazon from Dinosaur Electronics. A FAN50PLUS is most likely what you need.

[rodgebone]

the sail switch went out on my 2 month old Outback. fan kicked on and blew cool air but the furnace never ignited. after a few tries the system shut itself down. so doesnt sound like a sail switch from my experience. having said that its cheap and easy to replace if you can access it without disconnecting the wiring and gas line and pulling the whole unit out as was my situation. the last thing i wanted to risk was a leaky gas line so had the dealer do it under warranty

[cliff]

Had the same problem. Turned out to be both the control board and the flame sensor

[CedarCreekWoody]

I am basing my opinion of what is wrong from forum conversations I've read here and from what the factory told me was probably the problem based on my description of what the furnace was doing......if its not the sail switch so be it. I still need a model tech regardless.

And from what I've read here on this forum replacing the sail switch is a common issue......and it was the first thing the factory rep mentioned. Personally I don't care if it is or it isn't, I just want it fixed..... :)

You have the right idea...call a tech and let him diagnose it.

[DynoGuy]

I had a similar problem with my new 2019 Raptor 2 weeks after I got it this fall. Keystone in their infinite wisdom uses some pos micro circuit breaker for the furnace, it looks like a ATC fuse but it doesn't have the little fuseable link in it. The tech came out and replaced it with a std fuse and it's worked ever since. It's located in the main fuse panel.

[slman]

So, how about my 2006 ish. 18' trailer. I set the wall thermo. all the way to the 'off' position ( ah, ...er...doesn't say off, but push the setting tab all the way to the left, lowest setting) but the furnace fan comes on and won't shut off. ( It's like 39 degrees in the trailer, and colder outside of course). I pulled the fuse 15 amp to shut it off. What say you about why I have to totally kill power to the heating unit...or whole trailer... to have it stay off. ?

[sonofcy]

So, how about my 2006 ish. 18' trailer. I set the wall thermo. all the way to the 'off' position ( ah, ...er...doesn't say off, but push the setting tab all the way to the left, lowest setting) but the furnace fan comes on and won't shut off. ( It's like 39 degrees in the trailer, and colder outside of course). I pulled the fuse 15 amp to shut it off. What say you about why I have to totally kill power to the heating unit...or whole trailer... to have it stay off. ?

Sounds like the thermostat is not working. If you know how they are supposed to work, troubleshoot it otherwise just buy a new one and if that doesn't fix it, return it and order a new board. Make sure it's the Dinosaur brand, they are reliable.

[CedarCreekWoody]

Are you sure you gave the blower enough time to shut off? Once the burner cuts off the blower will run a short time to cool done the chamber.

[slman]

Are you sure you gave the blower enough time to shut off? Once the burner cuts off the blower will run a short time to cool done the chamber.
Even with the Propane Bottles shut off, no heat demand or cycle, it runs.

My view of it....the thermo. seems independent of the loop, and...senses the cold, and keeps running. Just for kicks, today I will go out to the trailer, plug power in, and run the furnace and see if it works while heating the trailer. That is- shuts off after 75 degrees or so.

[slman]

Took the Thermo cover off, looks like new. I observed the top switch making contact/ or not, moving it back and forth. Looked like the 'copper strip (tab) to make on/ off contact was too close, touching...making contact..IN THE OFF position.....thereby telling the furnace fan to remain on. I slightly ( very ) bent it out, and the system works perfect in the 3 cycles I ran it through. Simple fix for a simple old fashion switch mechanism.

[Augie]

Do you mind me asking how you finally resolved your problem? I have the same unit and am having the same problem. Also, we find that the furnace exhaust is really noisy compared to our previous trailer (actually had a complaint from a neighbouring camper last fall). Thanks for the feedback!

[sonofcy]

Do you mind me asking how you finally resolved your problem? I have the same unit and am having the same problem. Also, we find that the furnace exhaust is really noisy compared to our previous trailer (actually had a complaint from a neighbouring camper last fall). Thanks for the feedback!

Does it blow warm air before shutting down? If it does it is most likely a bad board. The Dinosaur brand are the best, look for a FAN50PLUS.

[Augie]

You bet, keeps the trailer toasty warm just really annoying, on-off-on-off etc. Also really loud, any thoughts about that?

[sonofcy]

You bet, keeps the trailer toasty warm just really annoying, on-off-on-off etc. Also really loud, any thoughts about that?

How deep is deep. Use your phone to get a DB reading at say 3 ft and report the number here, I will do the same.

[Augie]

Thanks S, can't now as I don't have immediate access to the camper, but will when I do! Just based on my judgement its much louder thank our Sprinter was to the point where we actually had an RV Park manager tell us that he had complaints last fall from other campers when we were in Fernie (and it was cold). Its not bad inside but being honest outside it sounds like a 737 spooling up!

[sourdough]

Thanks S, can't now as I don't have immediate access to the camper, but will when I do! Just based on my judgement its much louder thank our Sprinter was to the point where we actually had an RV Park manager tell us that he had complaints last fall from other campers when we were in Fernie (and it was cold). Its not bad inside but being honest outside it sounds like a 737 spooling up!


What furnace was in your last RV (btu)? They can be loud and are part of RVing. We just had a couple pull in next to us (45' wide spaces) and they used their furnace vs heat pump. It actually woke me up in the early AM - just part of it.

[Augie]

What furnace was in your last RV (btu)? They can be loud and are part of RVing. We just had a couple pull in next to us (45' wide spaces) and they used their furnace vs heat pump. It actually woke me up in the early AM - just part of it.

Both were/are 35,000 BTU ... not sure about make and model in our former camper. 🤷*♂️