Atwood Furnace Cutting Out - Montana Owners Club

Draaago · 01-02-2021, 05:03 PM

Hello all,
Wondering if anyone in the forum has had an issue similar to the one I'm having and I wasn't able to turn anything up in my search. My furnace (Atwood AFMD 35131), when triggered by the thermostat, will power up, start blowing and ignite with no problem. However, after a short period of time (between 5 and 30 seconds), it shuts off permanently.

I have had this same issue using both the OEM board and a Dinosaur board (Fan 50 Plus Pins). When the OEM board is installed, the instant it shuts off, it begins making a loud buzzing sound. Upon inspection, the sound seems to be coming from a relay on the control board and the red LED on the board lights constantly (no flashing). When the Dino board is installed, the instant it shuts off, the board begins making a quieter clicking sound and the LED lights up green (I believe).

I am trying to avoid paying a pro to come out and look at it (because that sucks) but I don't know where to look next. It hasn't been dire having been in FL for the past month, however, we'll be getting some cold weather soon and I'd really like to figure this out. I had hoped that installation of the Dino board would be the end of it. But alas, here we are. If anyone has any thoughts, ideas or suggestions, I would be very grateful.

Daryles · 01-02-2021, 05:42 PM

There is a furnace troubleshooting manual in the files section at the top of the webpage. Hope this helps.
Maybe start by swapping the black 15A self resetting fuse with another one (blue 15A spare or unused circuit) just for troubleshooting.

rohrmann · 01-02-2021, 06:51 PM

Another issue that can cause this problem is the gas regulator not adjusted so you are getting 11" water column of pressure to the furnace. Just because your stove works isn't an accurate indicator. You might need at least a mobile guy to come out and check the gas regulator.

Daryles · 01-02-2021, 06:58 PM

Quote:

Originally Posted by rohrmann

Another issue that can cause this problem is the gas regulator not adjusted so you are getting 11" water column of pressure to the furnace. Just because your stove works isn't an accurate indicator. You might need at least a mobile guy to come out and check the gas regulator.

Excellent idea. Switch tanks. They have separate regulators. Flip the auto switching valve over to the other tank.

**Carl n Susan** · 01-02-2021, 08:01 PM

What year and Model Montana do you have? The answer to your question may ee helped knowing these basic facts.

Draaago · 01-03-2021, 06:23 AM

@daryles I will take a look, thank you.

@rohrmann Will try switching over the tanks in a bit. Would be nice if it was that simple of a problem.

@carl It's a 2017 3730FL.

jjwhite368 · 01-03-2021, 04:47 PM

Check your 12 volt fuse panel. Find your furnace circuit and look for what is in the slot. If it is black (like the one in the picture) it is a self-resetting circuit breaker. Our dealer maintenance manager had us replace it with a standard 20 amp automotive fuse (yellow).

Our symptoms in our brand new 2021 3121RL were exactly the same. On, run for a little while, cut off. Wait a while, come on, run for a while, cut off. The dealership guy said he had seen this in a number of Keystone units (not just Montanas).

It was the fix, toasty warm after. We discovered the issue on our first night, a Sunday, and we slept with the best temperature all night at 58.

Draaago · 01-03-2021, 05:15 PM

@rohrmann I tried switching the LP tank and no dice, problem continues.

@jjwhite
When this all started, I was having a similar problem and the standard 15A fuse that was installed was blowing. I reached out to Atwood and they sent me a resetting fuse like the one you just showed and now the fuse "blows" but the furnace continues to make a sound (either buzzing or clicking, depending on which control board is installed). Are you saying that you've switched to a 20A automotive fuse? Is that safe if it is meant to be 15A? I don't know anything about electronics.

Thanks everyone for the help so far.

Daryles · 01-03-2021, 05:24 PM

If it was blowing fuses to begin with, you have a different problem. The blower motor draws the most current in the furnace. You may have a bad blower motor OR something (debris) in the blower causing it to strain drawing more amps than it is supposed to. You may need a tech to have a look if you are not comfortable doing a little disassembly to see how free the blower motor spins.

Draaago · 01-03-2021, 05:59 PM

I just switched it back to a standard 15A fuse (thanks, @daryles and @jjwhite) and it has been running for a little over 40 mins now with no problem. I am thoroughly confused. I know it has blown at least 2 standard 15A fuses in the past, though they were during different episodes of this ongoing problem. Why would it have the issue described with the slow blow fuse but then seemingly run fine with the standard 15A fuse? I'm gonna let it go on a while longer to see what happens, but would switching to a 20A fuse as described by jjwhite earlier be safe/appropriate?

Update: Ran for 1 hour straight and I shut it off. Confusion persists.

goodellj · 01-06-2021, 03:06 PM

I have been having the same problem. My trailer is 8 years old and I think the LP regulator is sticking. When I opened up the furnace I noticed a blinking red light on the control board. Three red flashes, pause, then repeats, which means "Ignition lockout Fault". No clues in the owners manual on what this means, and not much in the manual for trouble shooting. After researching it I found that it means low propane pressure or air in the line.

Check out my previous post at https://www.montanaowners.com/forums....php?p=1205113

After a couple of months of use, I am finding that the problem is with the right propane tank. If I flip the selector over the the left tank every works fine, and if I then switch over the right tank it works fine. But if we have a warm spell with no propane use I get the same problem. I think the regulator is putting out inadequate pressure from the right tank due to "sticking" in the regulator after not being used for a while.

I am planning to replace the regulator to see if it resolves the problem. There is a high pressure regulator on the right propane tank that I am considering replacing if the problem persists. If it continues after replacing that, I might have to call a qualified LP service tech.

Draaago · 01-06-2021, 04:24 PM

Thanks for the input. I will definitely be keeping a watchful eye on the tanks and regulator moving forward. Hard to say if switching the tank side or switching the fuse is what has it working now, but I'd prefer not to rock the boat at this point.

Thanks everyone for the help! This forum is a lifesaver.

amyed · 01-14-2021, 11:51 AM

I have a 2008 3400RL. Atwood furnace 8535-IV DCLP.
When turned on unit tries to light 3 times then stops. There is ignition so propane seems OK. I heard on a previous post to check the Sail Switch. I would love to but cannot locate it. If anyone knows the location or what it looks like I would appreciate it. Thanks Ed

**Carl n Susan** · 01-14-2021, 12:00 PM

Quote:

Originally Posted by amyed

I have a 2008 3400RL. Atwood furnace 8535-IV DCLP.
When turned on unit tries to light 3 times then stops. There is ignition so propane seems OK. I heard on a previous post to check the Sail Switch. I would love to but cannot locate it. If anyone knows the location or what it looks like I would appreciate it. Thanks Ed

Look in the Files section --> Manuals for the Atwood Furnace Training Manual
https://www.montanaowners.com/forums...?do=file&id=54
The number of blinks on the LED is an important starting point.

Then do a Search on "sail switch" and there will be a ton of information. Here is just the first that popped up and it includes a YouTube video of what you are looking for.
https://www.montanaowners.com/forums...ad.php?t=79400

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