Heater not working - what to do next?

[robmc5]

I know there are a lot of threads about this and I think I have read them all. I have a 2016 Thor PD31 Class C. I have not had it that long but I have had several issues I have fixed but this one I need some help on. The heater. Its an Atwood AFMC30141. Its been working fine until about a week ago.

The blower kicks on for a minute and then it fires, but only for a few seconds and stops. I am getting a three light error on the control board, ignition lockout fail. After reading a lot of fourms I have tried several things, mainly I replaced the OEM board with a dinosaur board (the old board looked like it had some water damage) I ordered a new sail switch also but its not the same one, the "sail" is not the same, not as wide as mine. Neither of these solved the issue. I cleaned the contacts, I closed the propane and slowly opened it several times, the gas stove works fine.

I am guessing the flame sensor is not detecting the flame, I know its there because I feel heat for the few seconds when it kicks on. I read somewhere to block the vent but I am not sure about that.

Can anyone direct me to the location of the flame sensor? I cannot seem to find it in the manual.

Any help would be greatly appreciated, this is our first RV and the community is pretty awesone,

[OldWEB]

Here is a service manual that includes the AFM series, so you have to pull out the info that pertains to your furnace. The best I could offer from reading some of it is...

• check gas pressure
• chk thermal switch
• chk gas valve operation
• chk sail switch operation

You need to use a multimeter for some of these checks, also the ignition probe is the flame sensor, dunno how to test it.


Gook luck!

[OldWEB]

AFM furnace

Here is a video on a AFM furnace for some reference, it is a control board problem but shows how to remove the burner (if you'd like to).

[robmc5]

Thanks for the help I was able to get it working, I am not sure what exactly fixed it but I replaced the board, the sail switch, cleaned all the contacts and its working great now,

[Mousemate]

One think just wanted to make sure you don’t have the bad furnace cover
See attached link.
https://www.thorforums.com/forums/f8...16-a-5865.html

[OldWEB]

Originally Posted by robmc5

Thanks for the help I was able to get it working, I am not sure what exactly fixed it but I replaced the board, the sail switch, cleaned all the contacts and its working great now,

That is good, it gets you familiar with the system for the dreaded 'next time'.

[Jusjay]

If your circuit board looks like this! That’s your problem. Try drying the area with a hair dryer. If not get a Dinosaur circuit board for your model.

[OldWEB]

If your circuit board looks like this! That’s your problem. Try drying the area with a hair dryer.

Not just a hair dryer, but use a small cleaning brush and alcohol (rubbing) to wash the crud and moisture off. Both sides if you are careful around some components. Then if you are really inclined, a thin spray of lacquer will 'seal the deal' on the board and offer a bit of protection.

[Hittntherooad]

I just went through the whole diagnostic scenario. I ended up replacing the burner. I would add to the video to spray soapy water on the gas valve connection to check for leaks. I got mine working again and went back out later to check it again and smelled gas. Sprayed the connection and one small bubble came up. Tightened again and good to go.

[Cpd]

Just ran out and looked at ours as we already had the board changed, used it once to try it. Then when we REALLY needed it this week in Texas, nothing.
There is white salty looking crap on some of the fixtures. Any suggestions please on whats best to use to clean it off?
Our cover is a grate, no louvers.
Thanks!