Furnace not working

[Mondoggie]

My coach furnace blows cold air. I can go outside, remove the cover, hit the reset button and the heat works as it should for one cycle then shuts off like normal. But then when the insides temps drop to the trigger level the fan comes on again but the propane doesn’t ignite (until I go outside and reset the unit).
Propane tank is at 50%, plugged into shore power and after I hit reset, I can hear the propane burning and the air from the register is good and hot until it shuts off.
Does anyone have any suggestions? RV is a 2019 Jayco Melbourne 24K.

[LegalBeagle]

I don't have an answer to your problem, but I can share your frustration. We're experiencing the same problem (furnace not igniting). I dropped our Greyhawk Prestige off at CW this morning to get fixed and was told that repair would be covered by warranty, but that it was most probably a defective sail valve (whatever that is) and that a replacement could take a month or more due a lot of these being defective and having to be replaced. I complained that warranty work sucks when it takes months to get something repaired, but was told by the CW people that it would take just as long even if not a warranty item due to backlog on this part. Has anyone else heard anything like this?

[RogerR]

I did a quick google and found sail switches from 10 to 30 $ and several do it yourself youtubes. Maybe easier to do it yourself? I did all my own warranty work as it was leaks, poorly screwed in items, trim attachment and 170 miles each way to the dealer.

[Mondoggie]

Yes. I just talked to a shop foreman and got the same story. They promised it would be covered by warranty but would not even guess as to when the sail valve would be in. The valve itself is 15 dollars but the guy says they have to pay $25 to get the tiny valve shipped.
I’ve seen the sail switch. Any shade tree mechanic could fix it in 10 minutes. It’s just a matter of getting the part.

[kurv]

Sometimes its not the switch being bad. They just aren't positioned correctly or get bent slightly from ice. The sail switch is just a micro switch with a small metal fin. When the blower comes on the air pushes the fin into the switch that tells the furnace its safe to fire. There are ways to test this before you replace the part. Sometimes even new ones need to be slightly adjusted before the work correctly.

[Mondoggie]

Kiev. I wondered about this. I’ve seen the part and thought about trying to bend it but not knowing how it should be angled I thought I’d leave it to the pros. Now in the light of having to wait a month or so on a new part, I’m starting to reconsider.

[kurv]

You basically want to take as much slack out of the movement of the arm as possible. As soon as slight pressure is applied, the small button should click on. An easy way to test the switch is take it out, hold the switch on and see if it cycles on off and back on again.

[RPR]

Try tapping on the switch with it still mounted. This has been found sometimes to unstick it that may give you heat till replaced.

[RPR]

Check Amazon for the switch. Looks like fast delivery.

[Mondoggie]

I don’t know how “on the ball” the guy I working with is, but what he’s telling me now is that the problem is not necessarily with the metal fin, but with the relay that the fin touches when the fan blows. If the relay is bad (and apparently this is a common problem with this model) it might not matter what shape the fin is. Right?

[Dananu]

Originally Posted by Mondoggie

My coach furnace blows cold air. I can go outside, remove the cover, hit the reset button and the heat works as it should for one cycle then shuts off like normal. But then when the insides temps drop to the trigger level the fan comes on again but the propane doesn’t ignite (until I go outside and reset the unit).

Propane tank is at 50%, plugged into shore power and after I hit reset, I can hear the propane burning and the air from the register is good and hot until it shuts off.

Does anyone have any suggestions? RV is a 2019 Jayco Melbourne 24K.

If pushing the reset makes it work it probably is not the sail switch. Maybe an overheat safety?

[pconroy]

Yeah put me in the "Huh? Sail Switch???" category too.


When our SS died, the furnace would not ignite - ever/never.


The purpose of the Sail Switch is that when the blower spins up and is pushing air, the switch's Sail catches the wind and closes the relay.


That tells the furnace that it's safe to ignite.


On my furnace a bad sail switch mean it never ignited, never blew warm air.

[Mondoggie]

Dang, I hope it’s the Sail Switch because that’s what warranty is replacing. The guy told me he checked it out for warranty approval but you couldn’t prove it by me. He came by the campsite while I was gone. Hmm...

[Edpare]

I also have a malfing furnace. My 5-month old Jay Flight SLX 8 248RBSW has a Dometic “medium” DFMD20 furnace. The thermostat will turn the blower on, but the gas won’t ignite.
Turns out it has only one duct, pointing down, that connects to 4 floor registers. Given that, there was only two ways to mount it: either with access to the burner, blower, and electricals easily available or with access completely blocked by the thick, impenetable, heavily insulated exterior wall. Guess which way it was mounted?!?
Yup, absolutely impossible to reach. Evidently, Jayco does not stand for genius. The saddest sight was the equally lousy job the installers did: they literally punched a hole through the floor, tearing it to shreds. Of the 6 screws that held the sofa together, only one was actually through wood. I wanted to cry when I saw the damage knowing I was past the dealer’s generous 30-day 50/50 warranty period.
I’m probably having the same sail switch problem but it looks like I will have to take out the sofa and the (loose) half-wall before I can even reach the furnace. To top it off, Dometic routed the metal gas manifold tube in such a way I will have to cut the sheet metal to access the SS and/or burner orifice. Nope, no inspection panel.
I wish I hadn’t been so gullible.
My local Jayco dealer says it will be 3 weeks before the service manager will even talk to me and I should “call Jayco”. Has anyone tried to call Jayco lately? I can’t, either.

[Mondoggie]

The fellow working on my rig said he was originally 94th on the caller waiting list. Said he hung on until he was into the 40’s but had to leave...

[Mondoggie]

RPR and RogerR. The part I need is for model # DFMD30111 which has apparently been replaced (maybe because it isn’t reliable?) by switch number 33082. I can find neither on Amazon but I did find the 33082 elsewhere online for about 18 dollars. The photo I saw of the switch and bracket looked very similar to mine, but in each case was listed as “out of stock“. I’m still looking but becoming pretty frustrated in the process~

[Mondoggie]

In case anyone is having the same problem with their Dometic furnace, here is an update.
After driving all over the Panhandle of Florida looking for a sail switch for my furnace, I finally found one online through Lebanon RV Center in Tennessee. (RVeParts.Com). The part had to be backordered but finally came in today and it took me less than ten minutes to replace it. The furnace has cycled through six or seven times now and so far the new switch seems to be working. (Note: the other switch was always "hit and miss" to so I may have to revise my statement later).
BTW, the original part has been replaced by one that looks and fits exactly the same. In my research I found that my original part (DFMD30111) has been replaced by part number 33082. To add to the confusion there was a note with my shipment that lists a different original part number. The note with my order says "Dometic D7E33063 has been replaced by part 33082, Sail Switch - Furnace Low Air Flow Switch: For Dometic Small/Medium/Large DF Series Furnace Models And Atwood Small/Medium/Large AF Series Furnace, Sail Switch; Black.
At any rate, the new part 33082 is doing the job for my 2019 Jayco Melbourne 24K. Also, Lebanon RV Center was helpful and good about keeping me posted throughout the backorder process.

[Superseneca]

A friend of mine had the same issue. He had the high temp limit switch replaced. Problem solved.

[CAG]

Ignitor Board Index page

Just for future reference. This is the go-to place for various RV appliance boards. He does not have everything but most of what we end up replacing.

No I don't have an interest in the business.

[Mondoggie]

Thanks. Good to know.