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07-27-2022, 11:10 AM
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#1
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Junior Member
Join Date: Jul 2022
Location: High River
Posts: 7
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Dometic furnace DFMD0121
Hello All,
We have a 2021 Keystone Bullet 290BHS with Dometic DFMD0121 furnace. The furnace blower runs for a bit then cycles off. I don't hear any attempt at lighting, have run the stove to check for air pockets in the propane line, and have been told to check the sail switch. I removed everything to pull it out but it seems stuck. Is it siliconed to the wall? Do I need to remove the exterior exhaust bezel to try to scrape it free? I don't want it down for two months at the dealer waiting for the repair mid season.
thanks!
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07-28-2022, 04:53 AM
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#2
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Senior Member
Join Date: Dec 2021
Location: Central Al
Posts: 118
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Sounds like you need to check and probably replace the sail switch
__________________
2019 Keystone Bullet QBS287, 2014 Tundra Crewmax 5.7
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07-28-2022, 05:06 AM
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#3
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Senior Member
Join Date: Mar 2014
Location: Mountain Home, Idaho
Posts: 3,010
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Look around the edges if the outer case for any screws that you might have overlooked that hold the furnace in place ..
No need to remove the outer duct .. it’s a tight fit and if you’ve been in areas with high humidity and salt air you may have a bit of corrosion to fight to get the furnace exhaust port to slide out of the wall vent tube..
Rocking it back and forth while pulling should break it free..
Since blower motor runs but you hear no ignition popping sound outside at exhaust and no LP smell most likely culprit is sail switch on an Atwood furnace ..
They are world famous lately for a cheap sail switch
__________________
2007 GMC Classic club cab 4x4 Duramax LBZ
2014 Alpine 3010 RE. 34 foot fifth wheel
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07-28-2022, 05:59 AM
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#4
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Junior Member
Join Date: Jul 2022
Location: High River
Posts: 7
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Thanks! I tried pulling, rocking, within reason worried about damaging the heater, but it didn't budge at all. The front, closest to me, lifts, but the back doesn't move and no additional hardware is present. I heard there maybe a lip on the front and the exhaust is super tight, thus exhaust port needing to come off for that extra movement. But I don't know.
No salt or lots of dirt, bought new, had for two seasons in southern Alberta.
Thanks for your responses.
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07-31-2022, 12:45 PM
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#5
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Junior Member
Join Date: Jul 2022
Location: High River
Posts: 7
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Had to remove the outside exhaust port to get access. So it’s firing now after replacing the sail switch, but only burns for a few seconds then stops. Blower continues, but I can’t get a continuous burn. I’ve run the stove for a while to clear any air. Thoughts?
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07-31-2022, 02:16 PM
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#6
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Junior Member
Join Date: Jul 2022
Location: High River
Posts: 7
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Tried running the stove and all that for airlocks. Almost like the propane stops, can’t smell it after it stops. Tried disconnecting propane as well.
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07-28-2022, 07:29 AM
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#7
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Senior Member
Join Date: Mar 2019
Location: Milwaukie, OR
Posts: 1,397
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Can you reach back with a phone to try to take pics around the part of the furnace you can't see? A borescope could also help you see what's holding it up.
Also, is the propane line disconnected?
__________________
Jeff & Sandi (and Teddy - 7lb Schnorkie)
2018 Montana High Country 305RL
2015 RAM 3500 Crew Cab 4x4 DRW
Demco Recon Hitch on RAM Puck Ball
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07-28-2022, 08:29 AM
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#8
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Site Team
Join Date: Feb 2014
Location: W. Texas
Posts: 17,676
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If you haven't removed the exterior exhaust and it's the only thing on the exterior wall from the furnace you probably should give that a try. I've had one (a year old) that was stuck so tight in that tube that I almost had to bend it up trying to get it off. Rocking and twisting finally got it to break loose. That will be hard to do trying to use the furnace to twist. I'm sure if it that tight it would feel like it was stuck.
__________________
Danny and Susan, wife of 56 years
2019 Ram 3500 Laramie CC SWB SB 6.4 4x4 4.10
2020 Montana High Country 331RL
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07-28-2022, 09:17 AM
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#9
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Senior Member
Join Date: Dec 2021
Location: Central Al
Posts: 118
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Is is screwed down to the floor at the base of the furnace?
__________________
2019 Keystone Bullet QBS287, 2014 Tundra Crewmax 5.7
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07-31-2022, 12:10 PM
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#10
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Junior Member
Join Date: Jul 2022
Location: High River
Posts: 7
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Had to remove the outside exhaust port to get access. So it’s firing now, but only burns for a few seconds then stops. Blower continues, but I can’t get a continuous burn. Thoughts?
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08-15-2022, 10:03 AM
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#11
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Junior Member
Join Date: May 2020
Location: Calgary
Posts: 16
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Quote:
Originally Posted by MrWonderful
Had to remove the outside exhaust port to get access. So it’s firing now, but only burns for a few seconds then stops. Blower continues, but I can’t get a continuous burn. Thoughts?
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I had the same problem exactly on mine. Had a mobile tech come out and he diagnosed it immediately as the burner orifice being misaligned. He said more common than you would think especially on new trailers. Took him less than 10 minutes and has run flawlessly ever since. By the way the mobile tech I used is in Okotoks. Let me know if you would like his info.
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07-31-2022, 02:36 PM
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#12
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Senior Member
Join Date: Jul 2022
Location: Elm Mott
Posts: 165
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Furnace Will Not Stay Burning
Quote:
Originally Posted by MrWonderful
Hello All,
We have a 2021 Keystone Bullet 290BHS with Dometic DFMD0121 furnace. The furnace blower runs for a bit then cycles off. I don't hear any attempt at lighting, have run the stove to check for air pockets in the propane line, and have been told to check the sail switch. I removed everything to pull it out but it seems stuck. Is it siliconed to the wall? Do I need to remove the exterior exhaust bezel to try to scrape it free? I don't want it down for two months at the dealer waiting for the repair mid season.
thanks!
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Not sure if your furnace is like a central gas furnace in a house but there may possibly be a "flame sensor" rod that needs to be cleaned with a steel wool pad. It would connect by wire to the main board if so.
On a house unit, if the flame sensor goes bad then the fan stays on but no gas and no ignition. Have you removed power from it and returned power? (turn the breaker off and back on)(reset the board)? Just a thought and trying to help.
__________________
Alpine Custom Upgrade in Elm Mott, TX
2021 Alpine 3650RL W/electric central heat
and 35 other inventions/improvements to it
2012 Freightliner M2 112 2L Conversions
450HP Detroit DD13 1,650 torque,
Allison 4000 automatic, 4.30 gear
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07-31-2022, 03:21 PM
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#13
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Junior Member
Join Date: Jul 2022
Location: High River
Posts: 7
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Thx I will!
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07-31-2022, 03:23 PM
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#14
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Site Team
Join Date: Jul 2014
Location: Modesto
Posts: 20,326
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When you put the furnace back in, did you make sure the two exhaust ports lined up?
__________________
2012 Copper Canyon 273FWRET being towed by a 1994 Ford F350 CC,LB,Dually diesel.
Airlift 5000 bags, Prodigy brake control, 5 gauges on the pillar.Used to tow a '97 Jayco 323RKS.
Now an RVIA registered tech. Retired from Law enforcement in 2008 after 25+ yrs.
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07-31-2022, 03:55 PM
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#15
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Junior Member
Join Date: Jul 2022
Location: High River
Posts: 7
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Yup, it’s going out.
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07-31-2022, 04:01 PM
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#16
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Site Team
Join Date: Jul 2014
Location: Modesto
Posts: 20,326
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What I mean is both tubes are inserted into the furnace tubes?
__________________
2012 Copper Canyon 273FWRET being towed by a 1994 Ford F350 CC,LB,Dually diesel.
Airlift 5000 bags, Prodigy brake control, 5 gauges on the pillar.Used to tow a '97 Jayco 323RKS.
Now an RVIA registered tech. Retired from Law enforcement in 2008 after 25+ yrs.
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08-11-2022, 07:40 AM
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#17
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Member
Join Date: Jan 2020
Location: TriCities
Posts: 55
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This might help in your adventure
https://www.keystoneforums.com/forums/showthread.php?t=51049
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