2015 Coachmen Leprechaun 319DS Furnace not igniting

[32Leperchaun]

I have a new to me, 2015 Leprechaun with a Dometic controlled, Atwood furnace. After it was not working from the git-go, a local repair guy suggested it might be the sail switch. Upon installing a new one, the furnace seemed to work fine, then off we go to our first trip. Just returned from that first camping trip and initially, the symptoms were: blower kicks on, then furnace would ignite and stay on for 5-10 minutes then shut down, now only the blower will come on...no furnace, then it shuts down. I checked the pc board and the indicator light was blinking once every 3 seconds or so, indicating limit switch / air flow issue. I watched a Youtube video where a guy pulled out the furnace with ignitor electrodes. He showed how you could hit the reset, get the blower going, then observe if the electrodes were igniting. Mine did not spark. they were a bit corroded, so I sanded them clean and still...no spark. The Youtube guy stated at this point, it could be the board or the part that had the electrodes. Any way to determine which would fix this? I see evidence that suggests this circuit board has been, at minimum, unscrewed and possibly replaced. Based on what I read, that because many of these boards are cheaply produced in china, that this one might have "gone bad"?

 

[Dominy]

I have a 2015 Coachmen Concord. We were up in Flagstaff last September and the last night we were there the furnace quit working. Probably the same as yours. We quickly tested everything we could think of and decided it was the motherboard. Got home and put a new motherboard in, and it still didn’t work. Replaced sail switch, no go. Watched several YouTube videos and finally realized that even though it was cool enough to need the furnace at night in Flagstaff, it was too warm in Sierra Vista for the thermostat to run the furnace. I waited until after sunset when the temp went down and sure enough the furnace came on. The new motherboard did the trick.

 

[Wilson310BHI]

You should also make sure the furnace is getting the right voltage; if you have lead acid batteries, they can go below 12 volts and the igniters need at least 12 volts to work.

 

[32Leperchaun]

Here's the conclusion to this issue: all sail switches are NOT created equal! Since initial purchase of my RV, less than 2 months ago, a local well-referred mobile RV guy, said the likely piece in the chain of components related to the furnace running properly, was the sail switch. He cited one on amazon and I ordered it. Upon installing it and putting everything back together, the furnace ignited and stayed ignited. At this point, an important little critical detail was not observed by me. We went off on our inaugural camping trip where the results were already explained in initial post. After rounds of trial and error, determining continuity of components and failing to get this thing to operate properly, I caved and called a more affordable mobile RV guy and showed him the sequence of events I was experiencing. At this point I realized that if I pulled out the sail switch and manually engaged it with the little button, I could get the igniter electrode to ignite and it lit, but would not stay lit. What that revealed is that the current replacement sail switch #2 was not "sailing" when mounted inside the blower housing. Here's the part I failed to observe (wasn't aware) a critical step in the process. The RV guy said that the blower will not stay ignited until I re-inserted the slide-out exhaust pipe insert. I unscrewed it from the furnace cover, and while still needing to manually engage the new sail switch, the furnace ignited and stayed ignited! However, it still would not stay ignited when new sail switch was screwed back into the blower housing (this time with straight blade, NOT angled blade). Despite this new sail switch having continuity, RV guy basically stated that all sail switches are not created equal, so I called a local brick and mortar RV supply place and found one. Big difference was the one I bought from local shop was nearly $40.00 (I get the difference in overhead), while all replacements I bought off the internet were about $6.00 each, one with angled blade, one without. I installed my new angle-blade, $40.00 sail switch, put everything back together and hit the reset button. It works!

 

[Wilson310BHI]

Thank you for the follow-up, that is good to know!

 

[Mr. Dan]

None of the last 2-3 things I’ve bought from Amazon worked - 1 not at all; 1 worked 1.7 hours!

 

[Tom55]

You also need to know that the sail switch is very sensitive to dust and dirt. A little bit of dust can keep the sail switch from working. Wherever your return air grill is in your RV, take it out and vacuum as much as you can in the return air space. There are usually no filters, so dust can really collect in that space. I found a small furnace filter that would "fit" my return air grill with a little modification. I'm reducing the dust that gets into the return. I have to clean the filter regularly.

 

[jimmoore13]

An afterthought: FWIW, I had a sail switch that worked on the bench but did not work in the furnace. I tested the sail switch 8 ways to Sunday with a multimeter, and it worked...switch closed when pressed...but, as you said, it didn't "sail" in the furnace. I did a field repair installing a new sail switch, and all was well.

So my "factory" sail switch didn't sail, but the replacement worked fine. I bought the replacement at an RV dealer, because waiting for an Amazon shipment was out of the question...it was COLD at night.