Dometic Furnace DFLD40 121 2018 North Point 377RLBH

[InMyImage]

Can’t quite find anything with details on my particular issue...

Furnace starts, blower motor runs, ignition works but after 10 to 15 minutes the reset switch flips turning it off.

The control board light flashes 1 time every 3 seconds indicating that it is a Limit Switch or Airlfow Problem.

I do not have an anemometer but we have airflow at all vents and all ducting has airflow and non of the hoses are kinked. One did have a pretty sharp bend but giving it a more graceful curve did not help.

Inspection of the interior vents and rigid ductwork didn’t reveal any obstructions along the path that would limit airflow.

I don’t have a good r (just a small pocket sized one) to monitor voltage draw at individual wires, but did use the One Control app to monitor batter voltage during operation and fault and it was bouncing between 12.8 - 12.9 volts the entire time (we are connected to 50 amp shore power).

Any feed back or additional things to investigate would be appreciated before I order a new limit switch given that there isn’t any easy access to the beast without physically ripping apart the basement.

Fortunately we have a heat pump also, but we are having about 3-4 hours each night that are 33-45 degrees so it can’t keep up. Supplementing with the fireplace and a tower ceramic heater has been able to get us through the last 2 nights but temps drop pretty quickly when I have to turn off the heat pump to avoid damaging it.

Thanks

[JFlightRisk]

Check through the videos on this gentleman's You Tube site. He's about the best for diagnosing any issues that I've found. I hope he helps.

https://www.youtube.com/results?sear...+rv+works+inc+

[InMyImage]

Thanks, have looked through his videos but didn’t see anything with quite our problem.

Will have to just keep googling and reading.

[bill3kirk]

Same furnace in our 2018 377 but never had that specific issue. Ours finally resolved with a new board and sail switch. I did find this on campergrid.com but sounds like you have addressed those various issues. If it were me I'd replace the reset switch. I also had to re-route the water lines because they ran them directly in front of the furnace making even harder to pull it out in a already hard to get to area.

On a side note, I saw a 2021 NP 377 in campground today. They finally put an access panel for furnace outside!

[InMyImage]

I was finally able to find a partial reference from 2014 that appears to be the source of them problem, too many vents covered trying to direct heat to the bedrooms. Unfortunately the linked source was retired, but the gist was enough to convince me that the limit switch was killed by me. ��*♂️

Can’t believe the way they placed the furnace and the scarcity of a replacement limit switch. Finally found them in stock in Michigan and had them overnight me 2 so I have a spare. In central Kentucky at the moment and weather is forecast to get down to 27 tonight ��.

Fortunately it doesn’t look like anything is in front it, but they are a lot of wires haphazardly routed in the compartment.

Can’t wait to figure our what kind of yoga poses I’m going to have to do to get my 6’ 1” husky frame in the limited space to fit me and pull the thing out ��

[bill3kirk]

Make sure you wear gloves. Several sharp edges.
On mine, there were two screws in front holding it to the base. Once those are removed it comes out pretty easy. Even easier if you remove the outside tube first. Putting it back in I found it much easier if you position the furnace and then the outside tube for alignment. I also replaced the foil tape with metal hose clamps for the connections.

[InMyImage]

Thanks, fortunately I’m a bit OCD about wearing work gloves and given the amount of small metal pigtails in the ducts, which I realized are from self tapping screws, I bet it’s pretty easy to either cut oneself or get metal slivers in your fingers.

I’m kicking myself for forgetting to pick up some hose clamps when we were in a nearby city doing some shopping but fortunately I also believe in having duct tape (the standard kind) in my toolsbox so I’ll tape them in for now and then go in and put hose clamps in later.

Actually I’m debating whether it would be worthwhile to get insulated hose or leave them as is to help keep the belly warm since it’s got a heated under belly for the tanks instead of tank heaters ��*♂️

[InMyImage]

Fortunately the Limit Switch was the problem, hopefully I never have to do any more furnace repairs! I completely misunderstood what you meant when you said you water lines were in “front” of the furnace and mine setup was worse than yours.

I left everything out to be extra certain it runs fine so now I have to put everything back together again but really need to change the foil ducts because they are almost all too long and have to many sags making more bends than advised in the manual. Actually my hoses look amost exactly like all the “don’t do” pictures in the installation manual.

Wish I had the right supplies to reinstall the outside exhaust tube because it was a major effort to get the furnace back in place partially becit looks like my furnace was mounted higher than yours, possibly because we have the hot water on demand system...

Either way, lesson learned, don’t cover the vents!

[bill3kirk]

Glad you got it resolved!
Where did you get the reset switch from....I want to get a backup

[InMyImage]

Haylett RV in Coldwater MI

https://www.haylettautoandrv.com/

Ask for Jody and tell him George Tackett referred you. Doesn’t mean much but it’s where I actually bought my RV from so it’s good to build the relationship.

I did buy his last two but he put in a new order and said he would probably have them in 3 or 4 days if I recall correctly.

[charliehorse20]

We have a 2019 Jayco Pinnacle. The furnace was just blowing cold air. Pulled the furnace out and took to rv dealer. They cleaned, not replaced the sail switch. Put the furnace back in the rv and same problem, it does not lite! Suggestions?

[InMyImage]

You probably will get quicker help if you begin a new thread. I imagine that most people who could help with that issue but didn’t have input for mine have already read it and won’t necessarily pay close attention to updates here.

That being said there were a couple troubleshooting steps in the furnace manual including details on how to cycle the wall thermostat inside the rv to reset the furnace.

from my research for my issue though, i hope they tested your sail switch before simply cleaning it and calling it done....

[bill3kirk]

Hopefully their cleaning involved a full bench test of the unit.

Do you hear the burner ignite and run a few seconds then stop, but the blower keeps going? There are many threads here about furnace issues. You'll also find them in just about every other Brand forum too since they all use the same hardware for the most part.

Do you have LP to the water heater and stove? In my 377 the water heater and furnace are next to each other so if one is getting LP its pretty good odds the other is too.

Turn the wall switch off for about 3 minutes and back on. See if that does anything. There could be other steps listed in the documentation you got when you bought the unit about the furnace, as well as a full parts diagram with part numbers. You may find some useful info here -
https://www.dometic.com/en-us/us/support (assuming you have a Dometic furnace)

Try the reset switch on the unit. Usually on top of the furnace. If none of that works -

I'd replace the sail switch first. Its a cheap part (around $10-15), easy to replace and may resolve your issue.

I agree with InMyImage too - starting a new thread will get more attention generally.

[charliehorse20]

Turned out to be the regulator on the propane tank

[bill3kirk]

That's great that you found a resolution.

[ALJO]

Newer Atwood furnaces had problems with the sail switch, not enough lift for the switch. Bench test was always OK, but soon after re-install furnace would quit on the sail-switch. Solution was to bend the lift fan van de sail switch. It regards to all models with sail switch in the front of the Furnace.

[InMyImage]

So then is it safe to assume none of your propane appliances worded either?

Or was it a pressure issue with the regulator?