Furnace won't light - simple fix

bigben · 10-31-2017, 04:29 PM

We have 2015 Thor Challenger with an Atwood furnace AFMD 35141. We spend very little time where temps drop into the 30s. Most times we use the electric fireplace and a small electric heater. Always keeps the cabin temp in the upper 60s to lower 70s without a problem. But on the occasion that we get caught in freezing temps, a functioning furnace is a must to keep the basement (water lines and tanks) from freezing up.

Looked all over the forums and found lots of info. Preparing to pull the furnace, I started taking pics of the wiring to make reinstalling easier. Of course the LED light was giving me the 3 and 3 blinks - telling me I had an Ignition Lockout Fault. So I was tracing the wiring and pull the red wire in the diagram below to shut off the power. What do I find but a RESET/OFF switch!! Nothing mentioned about anywhere else. Well after I pulled the wiring and reset the LED light, then reattaching the red wire, I turned the switch to off and turned the thermostat to a high temp. Nothing. Turned the switch to RESET - BINGO, BANGO, BONGO. Furnace started right up.

Wow - what a simple deal. I had followed all the instruction about turning the gas off, turning the furnace on, letting the blower run and trying to light...etc. Nothing.

Hit the hard RESET switch - fixed.

Just some info for the rest of you.

Note: I apologize that I don't have a better pic of the switch but I'd put it all back together before I remembered to post this. But the attached annotated pic should suffice.

nosticks · 10-31-2017, 05:17 PM

Knew about the switch. It's in the install manual among the wiring schematic. You can also accomplish a reset by pulling the fuse at the panel and reinserting it, which in my case was easier than opening up the furnace.

bigben · 10-31-2017, 05:21 PM

After spending several hours on line looking for info, as I said - I found the switch. Found nothing in any of the literature about an electrical reset other than the info that I sited. Hopefully this more direct info will save others lost time and/or $s to accomplish.

nosticks · 10-31-2017, 05:33 PM

http://www.americanrvcompany.com/ass...m-Furnaces.pdf

Page 8 left hand side.

bigben · 10-31-2017, 06:45 PM

Yep - I saw that. My furnace was getting gas, igniter was sparking but not lighting. Look further in the manual and fund instructions for reset. There is no reference in troubleshooting the 3-3 fault for resetting that switch just the process I referenced. In any case, just trying to make the RESET switch location clear. Thanks for the references.

Bob Denman · 09-22-2018, 12:46 PM

It's a good thing that this thread was rejuvenated at this time of year.

Folks are starting to try their furnaces out, and somebody will need this info!

Thanks!

g8r80 · 09-08-2020, 02:03 PM

Where is this reset button located?

nosticks · 09-08-2020, 02:16 PM

Quote:

Originally Posted by g8r80

Where is this reset button located?

If you would just read the previous posts, it wouldn't be a mystery.

g8r80 · 09-08-2020, 04:48 PM

Not really. Do I have to pull the furnace to get to it?

taylorbob1 · 09-08-2020, 05:38 PM

Not sure abt the Miramar/Challenger, but on my Vegas you need to remove the outside cover.
Then once inside the furnace cavity, you will see a switch or button

Let us know what you find

BTW...if you do a search on this website or even Google, you are likely to find photos, diagrams and videos of your particular furnace.

nosticks · 09-08-2020, 06:47 PM

G8r80,

My apologies, the link I listed several posts above shows exactly where the reset is located. I went back and pulled it up only to find it has been hijacked by some rv rental outfit.

So to answer your question. Go outside the rv and locate the panel surrounding the heater exhaust. There are 6 or 8 screws there. Remove them and the cover. The reset button is about where your left hand would be. It's small but it's there.

g8r80 · 09-08-2020, 07:34 PM

Well the blind pig found the acorn but unfortunately reset didn't fix the problem. it sounds like gas is not flowing to the igniter. I'll keep trying. Thanks for your help.

taylorbob1 · 09-08-2020, 07:43 PM

I guess I missed it
What’s your furnace issue?
- do you hear the igniter clicking ?
- does the flame ignite, come on briefly, and then go off?

g8r80 · 09-08-2020, 07:47 PM

Blower is working. I hear igniter clicking. It does sound like flame ignites, stays on very briefly and goes out. Then it repeats the process.

g8r80 · 09-12-2020, 12:14 AM

Bringing this thread to a close. Thanks for all the advice. My problem was a bad control board. RV is only 3 years old. Thor quality control strikes again.

**16ACE27** · 09-12-2020, 12:23 AM

Quote:

Originally Posted by g8r80

Bringing this thread to a close. Thanks for all the advice. My problem was a bad control board. RV is only 3 years old. Thor quality control strikes again.

How do you come to that conclusion since Thor did not make the control board or even the furnace? Atwood has a history of failing control boards.

However, if Thor incorrectly installed the furnace which caused the board failure then you would indeed, be correct.

Pete'sMH · 09-12-2020, 01:52 AM

Hope you bought a good Dinosaur board instead of just another crappy Chinese OE one.

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