Problem with Atwood furnace

Need to be careful as to what insulation is on the conductors.
It needs to be high temperature rated multi-strand wire. (Not building type stranded, should be around 100 strand)
hard to find these days is true appliance wire.
Thermoset insulation would be better then thermo-plastic.

Thanks for chiming in Chum lee. Nice to hear from someone who has had the exact same problem. I'll for sure plan on replacing to lower gauge wires. I might as well replace the hot too, since I only have 2 wires anyway -- a hot and a ground.

I had the EXACT same thing happen to my Atwood furnace. It looked to me like the yellow wire at the multi-point connector was under size and burned up starting at the at the connector due to excessive resistance. Exact same symptoms as you. I replaced/rerouted the yellow wire with 12 gauge wire and the problem went away. I didn't use the multi-point connector for the yellow wire but instead installed a separate spade connector. If I remember correctly I also replaced all the ground wires with 12 gauge wire.

Chum lee

That seems like the logical answer road-runner. The "Field Plug Assembly" is another molex connector of course, but hopefully it'll do ok. Maybe I should apply some dielectric grease? I'll also make sure that the clamp isn't holding the wires too tightly. Instead of the molex connector, I was considering just joining the wires using butt connectors. But, the entry into the furnace where the molex was and is supposed to be has sharp edges, and that would eventually wear through the wire insulation. Good luck with your water pump problem. Sometimes I think they put too small of wire gauge in these things. I'm considering using a thicker gauge from the inverter to the furnace actually.

ScottG wrote:
High resistance at the molex connector.

I'm going to agree with this guess. As to why the insulation damage stops at the clamp, the wires get bundled tightly there allowing greater heat transfer from the yellow wire to the others. I've been having an ongoing high resistance problem with my water pump power running through a similar molex connector.

I want to thank everyone for their input on this issue. Yeah Puddle Pirates, that's what I was thinking too. I finally got the furnace out and apart. NO easy task for any of it.

The gas valve coils checked out ok. The sail switch seemed to be ok. The ignitor seemed to be ok, but not sure how to test that really, nor how to test the motor. By what I've researched, even though there's no house battery, and I don't think it ever had one, someone could have wired an exterior battery or generator the wrong way at some point before I acquired the camper; reversing the hot and ground coming in to the camper. Either that, or, yeah, a bad plug. And/or maybe a bad motor even, as someone said.

Anyway, since the furnace is at least about 19 years old -- although I don't think it was used much as the burn chamber looks hardly used -- and since I have it all torn apart, I decided to replace some things because I sure don't want to have to go through all this again. So, I'm awaiting a sail switch, a motor, a field plug assembly, a limit switch, an exhaust wall gasket, and an electrode. I'll double check the tracing of the wiring going from/to the inverter in the mean time. But once done, it should be like a new furnace. I'll update once I get it all put back together and it's running.

I can’t add much else except I would take a real close look at the plug, to me that looks like it possibly could have somehow shorted in the plug. Or possibly a severely corroded plug connection.

Here’s hoping you sort it out.

Yeah enblethen. The ground wire is factory, so I don't know. I'm going to need to go to an RV dealer for another molex connector and have them bench test my board, so I'll ask the RV service techs about this. Weird though how the wire is only affected about 8" forward (towards panel) of the connector and about 2" back (towards furnace) of the connector. And of course the connector itself. I'm wondering if the connector went bad, and/or a bad factory crimp that has finally manifested itself(?). Anyway I'll see what the techs say and let yas know.

enblethen wrote:
That was an extremely overloaded conductor. I see that the pin going into the furnace is melted.
What does it look like inside the furnace?
I would do more searching to see what caused this overload.

I will second that and suggest installing a new wire.. A BIGGER WIRE to replace it... If it is ground you could just parallel.. but make sure it's at least 2x the diamater of the old wire.

With the wire damage I am assuming serious voltage loss. if that's the ground this means the Blower may not be blowing fast enough to sail the sail switch (The blower is the big power hog in the furnace) if the sail switch does not sail.. the control board will NOT light the furnace.. Safety thing don't you know.

If it lit the furnace without enough air it could melt the heat exchanger and then either 1: Start a fire or 2: You might go to sleep... .and never wake up (CO Poisoning) . I've heard of both happening with portable propane heaters (never an RV furnace though because of the safety interlocks)

ScottG, that could be the problem, considering that the area affected was just before and just after. Question now would be why tho.

shastagary, I'll check those things as soon as I can get the darn thing out of the rig. It's not easy in this Alaskan Camper. I think I'll have to take apart some cabinet areas to do it. And they are glued at the joints, which means that I may have to re-fabricate those areas when putting it all back together. Fun fun :/.