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10-16-2020, 05:54 PM
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#1
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New Member
Join Date: Jun 2019
Location: Chesapeake
Posts: 1
M.O.C. #24363
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My furnace will not stay lit
Hello everyone,
I am looking for some guidance before I start tearing apart my furnace. I have a 2018 Montana Legacy 3950BR. The problem I have is the furnace will not stay lit. I hear it fire up and stays lit for about 10-20 seconds then blows out and re-lites. The ingniter works and it gets gas, just wont stay lit. I think it could be a thermo valve or actuator that is not working correctly. Your help is much appreciated.
Joe
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10-16-2020, 06:30 PM
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#2
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Montana Fan
Join Date: Nov 2019
Location: Roseville
Posts: 266
M.O.C. #25257
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First thing I would check is the sail switch.
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Jim and Carole
Roseville, MN
2018 RAM 3500 DRW, Diesel, Long Box, Air Lift Bags - 2020 Montana HC 381TH, Sailun S637
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10-16-2020, 07:22 PM
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#3
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Site Team
Join Date: Oct 2005
Location: Carmichael - CA
Posts: 7,695
M.O.C. #4831
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__________________
Carl (n Susan)
There is more to life than fuel mileage.
2012 Montana 3700RL Big Sky Package towed by a 2015 Ford F350 6.7L PSD 4WD CC LWB
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10-17-2020, 07:03 AM
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#4
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Seasoned Camper
Join Date: Feb 2019
Location: Saint Louis
Posts: 63
M.O.C. #23419
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I had a simialr issue with my 384BR. It would light and go out. I ended up pulling the burner suspecting a bug or cob web. The burner was full of water and corroded. Dometic is familiar with water getting into the burner area on the vertically mounted furnaces and replaced the corroded parts. Water was entering through the exhaust vent. I installed a dryer vent cover over the exhaust but removed it when the techs at the Goshen Rally caulked around the exhaust flange and it seems to have stopped the water entering.
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2019 HC 384BR
2022 F350 KingRanch FX4 LB
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10-17-2020, 01:39 PM
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#5
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Montana Master
Join Date: Dec 2017
Location: Mountain Home
Posts: 864
M.O.C. #20949
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Since the furnace actually fires off the Sail Switch ISNT what is causing your issue.. the furnace will not have ignition nor will the gas valve open if sail switch doesn’t make contact when blown closed to complete the circuit...
I’d suspect the flame sensor is not seeing the flame correctly due to dirt, mud daubers, or improperly positioned flame sensor/igniter.
The flame sensor is what tells the furnace control module “I see a flame” and tells gas solenoid valve to stay open...
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10-17-2020, 04:33 PM
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#6
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Montana Master
Join Date: Mar 2017
Location: Winchester
Posts: 903
M.O.C. #19514
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Has it rained lately? Ours wouldn’t stay lit one day shortly after we had a rainstorm where the rain came in sideways. Once the igniter dried out, it worked well.
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2017 High Country 305RL
2015 Ford F-250 Super Duty
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10-17-2020, 04:43 PM
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#7
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Montana Master
Join Date: May 2011
Location: Hixson
Posts: 3,436
M.O.C. #11397
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Quote:
Originally Posted by Loneoak
Has it rained lately? Ours wouldn’t stay lit one day shortly after we had a rainstorm where the rain came in sideways. Once the igniter dried out, it worked well.
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I had this issue a couple of times too. Sail switches get a bad rap. I have never had a sail switch fail even during 9 + years full-timing.
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2018.5 Montana 3791RD
Full Timers 9/1/2010 through 1/16/2020.
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10-20-2020, 10:50 AM
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#8
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New Member
Join Date: Sep 2017
Location: Ontario
Posts: 9
M.O.C. #20553
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I just had this problem a couple of weeks ago on our 2007 3000RK. The flame ignited and seemed to burn strong, but then went out. I was convinced that the flame detector was bad, so I ordered a new igniter/ flame detector. But then decided I would just blow out the flame tube incase a spider web or something else was impeding the gas flow. The dust and rust just flew out. Presto, it worked fine and has ever since. So get a source of compressed air and blow through the tube at the air intake. Good chance it will solve your problem.
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Belti Guy
2011 Chevy 2500 Duramax
2007 Montana 3000RK
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10-20-2020, 02:08 PM
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#9
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Montana Master
Join Date: Oct 2015
Location: westminster md
Posts: 2,328
M.O.C. #17894
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Just had the same issue. I used my battery blower and blew air in for like 5 mins. Worked great afterwards.
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2018 Chevy 3500 LTZ Dually Diesel 4x4 CCLB
2011 Montana 3455 SA. 6 point level up. Disc brakes. Curt Q24 Hitch. 5 step glow steps
Progressive EMS. Valterra tank valves. Sailun G637 tires. ARP fridge control. All led lighting. Mor Ryde IS
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10-21-2020, 05:51 AM
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#10
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Montana Fan
Join Date: Sep 2016
Location: West Melbourne
Posts: 314
M.O.C. #18980
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Quote:
Originally Posted by Belti Guy
I just had this problem a couple of weeks ago on our 2007 3000RK. The flame ignited and seemed to burn strong, but then went out. I was convinced that the flame detector was bad, so I ordered a new igniter/ flame detector. But then decided I would just blow out the flame tube incase a spider web or something else was impeding the gas flow. The dust and rust just flew out. Presto, it worked fine and has ever since. So get a source of compressed air and blow through the tube at the air intake. Good chance it will solve your problem.
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Same situation for me as well but I sucked the junk out with a shop vac.
__________________
Butch and Kathy
2016 3160RL Legacy, Sailun S637, Centramatic Balancers, 2-T105s, Amish Refrigeration, ARPrv, SoftStartRV, FlexArmor roof
2016 F350 6.7L SRW
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10-21-2020, 02:40 PM
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#11
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Established Member
Join Date: May 2019
Location: council bluffs
Posts: 42
M.O.C. #24154
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Have you noticed a difference in operation as you find yourself in higher elevations (up in the mountains)? We have the same issue you describe, and it gets progressively worse, the higher the elevation.
I don't understand how the burner gets rusty in the vertically installed units, assuming water enters through the exhaust vent. The burner tube exhaust is at a low point and the tube winds around inside the unit from low point to high point and then back down, around a few bends. I know the saying, "if water can get in, it will", but up hill AND around the bends?
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10-21-2020, 03:05 PM
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#12
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Seasoned Camper
Join Date: Jul 2019
Location: Pahrump
Posts: 65
M.O.C. #24555
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I had to replace the sail switch for the same reason
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10-21-2020, 08:02 PM
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#13
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Montana Fan
Join Date: Mar 2019
Location: Heber City
Posts: 129
M.O.C. #23676
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Heater Gremlins
Quote:
Originally Posted by Greg n Tracy
Have you noticed a difference in operation as you find yourself in higher elevations (up in the mountains)? We have the same issue you describe, and it gets progressively worse, the higher the elevation.
I don't understand how the burner gets rusty in the vertically installed units, assuming water enters through the exhaust vent. The burner tube exhaust is at a low point and the tube winds around inside the unit from low point to high point and then back down, around a few bends. I know the saying, "if water can get in, it will", but up hill AND around the bends?
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I have the exact opposite problem. When I'm in my neck of the woods between 5000 and 7000', it works great. When I go to the coast at sea level, it won't stay lit.
__________________
Craig and Mary
2024 Montana 3123RL
2024 GMC 3500HD
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10-26-2020, 09:37 AM
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#14
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Established Member
Join Date: Jun 2020
Location: Fallon
Posts: 37
M.O.C. #26474
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Had the same issue. Opened up the cover and wiggled the switch closest to the cover, assuming it is the sensor switch coming directly from the thermostat. It turned on and off as I wiggled it....pretty clearly the problem.
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decarteaux in Fallon, NV
2008 Montana 3400RL, 2006 Dodge Ram 2500 HD Laramie w/Cummins 5.9L 24 valve TurboDiesel. Andersen Ultimate hitch
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