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Old 02-01-2019, 05:54 AM   #1
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Model: Four Winds 24F
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THOR #12596
Heater issue - flame comes on intermittently and wont stay lit

https://youtu.be/0WahKBLEUgQ

6 month old 24f furnace started doing this on our new years camping trip. Temps were in the 30s at night, tank was full, medium and low and it would do this. Thought it was a 12v problem so put new batteries in halfway through our trips and topped off the propane. Took it to the dealer and just got it back. They cannot recreate problem and furnace is working great. Any ideas? Temperature, regulator, thermostat???. What else can cause this and what can I do to resolve?
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Old 02-01-2019, 11:45 AM   #2
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if the blower was working, which is powered by the 12v system, then it was not your batteries, otherwise nothing else would have been working...

the blower typically does not run when the furnace is not ignited, which tells me that your furnace's temp sensor may not be working properly - making the blower think that the furnace is ignited, when it is not...

yes, the furnace ignitor will kick on and off, as needed, during it's run, but normally it does not stay on for only 30seconds or less. If the temp sensor is not registering the temp at the end of the flame correctly, it could be causing this problem. This sensor can be changed out - watch this video:
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Old 02-01-2019, 01:47 PM   #3
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Moisture on the control board can cause this. At best it prevents the control board from seeing the flame lit so it times out and shuts down the furnace. At worst nothing runs when the control board is wet. The dealer gets it when it is dry and can't recreate the problem.

EDIT:

I didn't notice your Youtube video in the OP but what you have is exactly what happens to my furnace when rain intrudes and wets the controller board.
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Old 02-01-2019, 02:34 PM   #4
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If I may add, that was an excellent walk around video you did!!!! It normally takes most "YouTubers" 25 minutes, starting with the history of RV's and why you need a furnace, to get where you did in less than 2 minutes..Nice and thorough. The Service man's video was great (and short) also. Hope you get it resolved and sleep warm!!
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Old 02-01-2019, 04:03 PM   #5
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Thanks a bunch for the comments and advice.

Where exactly is the control board located? I think maybe I will just buy a spare and keep it on hand and swap it out if this happens again.

If it is the board getting wet, how can we prevent the board from getting wet in the future?
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Old 02-01-2019, 04:23 PM   #6
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Also check for air intake obstructions (or exhuast). I had a home made HD bug screen on mine and it was restricting the air flow and was acting simular to what you described. Perhap something (bugs, leaves, pine needles) are obstructing this? When you take the outside cover off you can see inside the entire intake and exhaust ports.
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Old 02-01-2019, 05:44 PM   #7
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To see the board take the 2 screws out of the exhaust pipe and wiggle and pull it out. Then remove the 4 screws on the compartment lid and open that up. You will see a 3x4 inch circuit board slid into a plastic tray. Water can come in through a the compartment door seams and drip on the board or land on the wires which run down to the board. Mine even had mold and gunk growing on top of and underneath the board. Sometimes it can just be allowed to dry and be alright. Sometimes the board has to be replaced. I drilled holes it the plastic tray to let water escape. I tied the wires back, so they wouldn't get wet and drool onto the board. Then I sold my MH, and I've not had any more problems.
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Old 02-02-2019, 12:01 AM   #8
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Were you at extremely high elevation? Say above 8000 feet? Propane appliances do not like high altitudes. I had a slightly similar problem myself. My heater would run for a minute then shut off, then 2 minutes later it would cycle again. In my case I had installed a digital thermostat which is way more sensitive. (less temp swing) my thermostat is located in the aft bedroom right above the hot air duct and closed to the main hot air duct buy the furnace. So, the thermostat would reach selected temperature very fast and the rest of the coach would be cold. My temporary solution was to block the hot air duct in the bedroom with my laundry bag and close the the bedroom curtain 3/4 of the way so the hot air is slower to reach the the thermostat. works perfect now. I am going to order some adjustable heater vents so I can close off some of the hot air in some areas ad get full flow in others. fine tuning
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Old 02-02-2019, 02:38 AM   #9
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Quote:
Originally Posted by sanjaun2 View Post
Were you at extremely high elevation? Say above 8000 feet? Propane appliances do not like high altitudes. I had a slightly similar problem myself. My heater would run for a minute then shut off, then 2 minutes later it would cycle again. In my case I had installed a digital thermostat which is way more sensitive. (less temp swing) my thermostat is located in the aft bedroom right above the hot air duct and closed to the main hot air duct buy the furnace. So, the thermostat would reach selected temperature very fast and the rest of the coach would be cold. My temporary solution was to block the hot air duct in the bedroom with my laundry bag and close the the bedroom curtain 3/4 of the way so the hot air is slower to reach the the thermostat. works perfect now. I am going to order some adjustable heater vents so I can close off some of the hot air in some areas ad get full flow in others. fine tuning
Sea level, at big sur on central CA coast.
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Old 02-09-2019, 09:41 PM   #10
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This just happened to me.

Quote:
Originally Posted by acheron800 View Post
https://youtu.be/0WahKBLEUgQ

6 month old 24f furnace started doing this on our new years camping trip. Temps were in the 30s at night, tank was full, medium and low and it would do this. Thought it was a 12v problem so put new batteries in halfway through our trips and topped off the propane. Took it to the dealer and just got it back. They cannot recreate problem and furnace is working great. Any ideas? Temperature, regulator, thermostat???. What else can cause this and what can I do to resolve?
Turned out to be the Fail SAVE switch. Took about 10 minutes to fix. Works great now. This switch has a flap on it. The fan for the furnace pushes it out so the igniter kicks in and stays running. If this flap is week it wonít stay out and it shuts the gas off. At least thatís my understanding. The guy who fixed it said mine was the 5th one he replaced in a couple of months. Hope this helped.
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Old 02-14-2019, 04:21 AM   #11
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Finally got the dealer to see the issue just by luck. Seems like the issue would come and go.

They took everything apart and found the igniter to be loose. Tightened everything up and bench tested fine.

I guess we will see if that resolved it.

Moho still under warranty but will be expired in June. Uploaded the videos to youtube and have the documentation at dealer just in case issues end up coming back.

I am hopeful though.
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