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Old 12-04-2017, 04:43 PM   #1
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Furnace won't light - simple fix - updated

I need to followup on the original post found here: http://www.thorforums.com/forums/f8/...-fix-9943.html

We normally use our electric heaters while we are traveling in the winter but due to a family illness -we have had to go back to the land of the cold in Kentucky. Weather forecast is horribly cold for this week (mid teens) and I fired up the furnace to make sure we were ready. What I found was NO FIRE in the furnace = no heat for the basement. Fortunately we had a couple of days before the cold set in.

Symptoms again:

1. Fan started up.
2. Slight smell of propane.
3. Ignitor was heard sparking.
4. No ignition
5. Furnace attempted to start 3 times.
6. After 3 failed attempts the control board began the 3 blinks, 1 second, 3 blinks coding indicating a soft lockout.
7. After about 30 minutes furnace soft lockout cleared and sequence above was repeated.
8. Using the reset button on the furnace, this sequence can be bypassed and the soft lockout is reset.

After reading a great deal from several sites (as I'd already done), I decided it was either a clogged burner or the controller board. Got hold of Atwood customer service and they indicated that these two issues sounded correct. The emailed me the specific manual. I found the controller board on line but decided to try and clear a clog.

I opened up the furnace on the outside of the coach, shut off the propane, removed the propane lines, fired up our stand alone compressor, reset the furnace, waited for the ignitor click and then started blow air into the furnace propane regulator. I did this for each of the three cyles, hit the reset again and then blew more compressed air into the regulator.

I then reconnected the lines, hit the reset button and ShaZZam - igniting. I let the furnace run some more, shut it down and then had it start back up. I still had the love - furnace is working great, ready as we can be for the fierce cold.

Here is the specific manual for the AFMD 35141 Atwood Furnace. Hope all this helps.
Attached Files
File Type: pdf AFM AFMD35141 manual.pdf (1.14 MB, 483 views)

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Old 12-04-2017, 06:32 PM   #2
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Here is a pic of the propane connection that I removed to blow air into the burner area.
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Old 12-04-2017, 06:46 PM   #3
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Smart fix. If I’m ever in a frozen tundra and have furnace issues, I hope you’re somewhere nearby. 🤞
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Old 12-04-2017, 06:49 PM   #4
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Larry - if wasn't for a serious family illness I wouldn't be anywhere near here now. But if you do have issues - PM me and I'll try to help. UUGGHH - hate this cold.
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Old 12-04-2017, 06:57 PM   #5
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Thanks bigben. Sorry about the family illness. Wishing you and family well...and warmer climates.
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Old 12-04-2017, 07:08 PM   #6
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Considering that propane burns clean (supposedly), how do you think the burner became clogged and do you think there is a proactive measure that could prevent this from happening?
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Old 12-04-2017, 07:16 PM   #7
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bigben,
I hope that everyone heals up quickly and completely... soon!
We're saying a prayer for you and your family.
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Old 12-04-2017, 07:19 PM   #8
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Quote:
Originally Posted by schreinertms View Post
Considering that propane burns clean (supposedly), how do you think the burner became clogged and do you think there is a proactive measure that could prevent this from happening?
Almost certain critters like mud dobbers are the fault.
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Old 12-04-2017, 07:20 PM   #9
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bigben,
I hope that everyone heals up quickly and completely... soon!
We're saying a prayer for you and your family.
Thanks for the kind thoughts and prayers
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Old 12-04-2017, 07:55 PM   #10
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Quote:
Originally Posted by bigben View Post
Here is a pic of the propane connection that I removed to blow air into the burner area.
Great post! Thanks for the info, the picture and the manual.
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Old 12-04-2017, 09:18 PM   #11
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X2 or many for the post! Spiders can be an issue. Good luck and keep warm.
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Old 12-05-2017, 01:39 AM   #12
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Possibly a screen over the exhaust

Quote:
Originally Posted by schreinertms View Post
Considering that propane burns clean (supposedly), how do you think the burner became clogged and do you think there is a proactive measure that could prevent this from happening?
I've read other post that descibe putting a screen over the exhaust pipe of the furnace to prevent insects or such critters from entering the burning chamber. I may try that but I know for sure if you fire up the furnace periodically - bye bye bugs. Also, knowing now how to blow through the chamber really builds my confidence that I can fix this again fairly quickly.
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Old 12-05-2017, 02:35 AM   #13
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Quote:
Originally Posted by bigben View Post
I've read other post that descibe putting a screen over the exhaust pipe of the furnace to prevent insects or such critters from entering the burning chamber. I may try that but I know for sure if you fire up the furnace periodically - bye bye bugs. Also, knowing now how to blow through the ychamber really builds my confidence that I can fix this again fairly quickly.
I added screens over the furnace, water heater, and fridge vents to help avoid this.
Furnace and fridge were Camco specifically made for purpose... Water heater was just a piece of window screen cut to fit inside the grate.
So far has worked well.
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Old 12-05-2017, 04:34 AM   #14
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Quote:
Originally Posted by bigben View Post
Almost certain critters like mud dobbers are the fault.
Yup me thinks so as well or spider cobwebs.
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Old 11-30-2018, 01:16 AM   #15
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Another furnace problem fixed

2017 Vegas 24.1 Atwood furnace would not stay lit.
It was very inconsistent, but usually would not light
I smelled gas, so knew it was getting propane
I heard the spark. You know....3 times and then it would cycle out.
It’s still under warranty.
But after reading the forum about spiders and wood shavings clogging the orifice, I decided to take the matter into my own hands. (Also, I didn’t want to go to all the trouble of taking coach to dealership & then getting the 2-3 week “sunshine treatment”)

So I turned off propane, then disconnected propane from the furnace
I then removed the entire ignition & flame assembly
Then blew it all out with compressed air
Then I moved & bent the two spark tongs closer to the burner for easier ignition
Then I reassembled
Now works perfectly on the first spark every time
Stays lit & doesn’t go out unless normal heat cycling occurs.

It was a very simple fix, and the unit comes apart easily with a few screws
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Old 11-30-2018, 01:29 AM   #16
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Gotta say - this came up again this year. Did the same thing again this year. Turned off the propane, disconnected the line (as I described above), cycled the furnace waiting for the ignition sparking and injected air from my compressor at about 140 PSi. Cycled the furnace 4 times. Reconnected the lines, turned the propane back on - worked like a champ. Took about 15 minutes. Good thing - temperature hit 26F in South Carolina.
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Old 11-30-2018, 01:36 AM   #17
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Quote:
Originally Posted by bigben View Post
Gotta say - this came up again this year. Did the same thing again this year. Turned off the propane, disconnected the line (as I described above), cycled the furnace waiting for the ignition sparking and injected air from my compressor at about 140 PSi. Cycled the furnace 4 times. Reconnected the lines, turned the propane back on - worked like a champ. Took about 15 minutes. Good thing - temperature hit 26F in South Carolina.
Ben - Did you install "critter" screens before it happened this last time?
Just curious if the cause is something else.

Would firing it up monthly be a good proactive approach we all should take?
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Old 11-30-2018, 12:16 PM   #18
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BandG - I did NOT install the screens thinking I'd fire up the furnace once a month to eliminate the issue. Having had to do this again, the screens on the exhaust are going on. Firing up the furnace once a month didn't seem to work.
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Old 12-24-2018, 02:50 AM   #19
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Mine was working fine last weekend. This weekend it flame on when started but the flame goes out. This happens each of the 3 times it attempts to light until it locks out. Reset it and it goes through the same cycle again. I guess I'll break out the compressor tomorrow and try blowing it out. I've owned 4 different RVs over 20+ years and never had to do anything to the furnaces: they just worked when called upon.
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Old 12-24-2018, 03:02 AM   #20
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And just when I gave up on it for tonight I turned it off at the furnace which killed my AC fan running since the furnace powers the thermostat and I was using the AC fan t0 circulate warm air in the MH from the electric heater, so I turned it back on and on the third light attempt it stayed lit. So it's working for now. I may delay the blowout until we return home Wednesday since it's supposed to warm up the next few days.
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