I would like to troubleshoot an apparent electrical problem in my Forest River Sierra 5th wheel RV. The furnace is

This furnace is from the Suburban Manufacturing Company. I guess it's 12 volts. I don't know where to find the model number, but the paperwork for it lists models SF-20, SF-25, SF-35, SF-42, SF-20F, SF-25F, SF-30F, and the SF-35F.

Thanks for the update. I am working on it right now and will get right back to you.
It took me this long to figure out how to get the cover off. There are two red wires plugged in. One comes from outside the box and it smaller with a white wire encased with it. The other red is thicker and is connected to another small part in front. I unplugged the thicker one in front. Was that the right one?

I tried a 15 amp fuse and it sparked but went in with out blowing. I took it out to check and then put it back in. Is it normal for it to spark? I am not sure how to access the blower wheel.

There was a model number on a sticker attached to the cooling portion of the unit but when I touched it with a dampened finger to clear the dust it vanished into a smudge. I could not find a separate model number for the furnace unit. The paperwork that came with it does list model numbers as Suburban Manufacturing Company SF-20, SF-25, SF-35, SF-42, SF-20F, SF-25F, SF-30F, SF-35F, and SF-42F.


The thermostat does control the roof AC and the Furnace.

There is an outside panel that gives access to the electrical.

The panel under the refrigerator opens to reveal the furnace itself. It is encased in aluminum and with the front panel off I can see inside but I can't reach a fan.

Thanks for you help. I will be back to you soon.

OK. This thing is beginning to irritate me. To start with it is an SF-30F if that helps.
It would appear that the cabinet was installed after the heater because the heater cannot be lifted over the lip of the cabinet without running into interference from the top of the housing unit which is fastened down to the floor. I would try to loosen the base housing screws but the furnace now will not go all the way back in because something is hitting in the back.

Also, I disconnected the gas line, but it looks like I will need to take off the elbow ( which is stuck) to gain clearance on the right side. But, as I said, even when I get the elbow off, the front triangular foot of of the furnace will not clear the lip of the opening by a long shot.

I guess I need help figuring out how to push it back in far enough to undo the base of the housing unit so that maybe the whole thing will come up far enough for me to get it out.

Then theres always my jigsaw.

Good. I got the furnace out. I blew it off. The fan spins without interference. Now what?

One thing I did notice when I was unhooking the red wire is a blue wire going nowhere. Does that mean anything?

OK. The heater is blowing all right and now I'm thinking that that wire might have been intermitantly touching metal causing the short. But I can't figure out where it is supposed to be going or if it is an extra lead for something I don't have. Should I just wrap it in electrical tape and put it all back together, hook up the gas and see if it fires up and blows warm air?

PS Is it normal to see a spark when installing a fuse?

The lock nut on the gas line will not thread tightly onto the elbow. It pops off every time I try to tighten it up. Of course I'm trying to be sure its seated squarely before I screw it down and it just won't tighten. Next stop? An elbow at Home Depot or what?

The blower does blow.

This nut will not even begin to seat itself. I understand about getting it started and wiggling the tubing to square it away and to tighten it up, but this one just will not get itself started with any thread grabbing at all. It might appear to be started but onegentle tug breaks it loose verifying that it was never really started.

Thanks. I havelooked and I can't find another fitting the right size. I am going to try buying another one if I can't fix the old one. I'll take it off and go to the hardware store with it. I'm not sure how to re flare the tube end.

OK. I'm going to the store and taking the wife to the doctor. I will be back in touch in a couple of hours. Thanks for all your help. Just respond so I have the ball back in my court.

11PM We were late getting home because we went to the doctors and ate. I got a 3/8 inch plug then realized when I got home that it wasn't a flared plug; went back and got the flared plug and it did rethread the nut well enough to seat it properly and now it's tight. The blower is blowing well. The furnace is sparking but is not igniting. The propane seems low; so maybe the gas pressure isn't high enough to facilitate ignition?

Taped the hanging blue wire presuming it to be the culprit. Without any apparent place to plug in I'm thinking that it may have slipped out of a thin band of tape that was holding some other wires in place (with it).

Does that sound plausible?

Could the blue wire have been doing nothing and just shorting the furnace? I can't see anywhere that it came out of.

You did a good job helping me. Thanks. Just check in with me tomorrow and I'll authorize payment after our last communication.

Brian

Good news. It is blowing hot air! Leaving the burners on did the trick.

The wires I'm refering to have yellow , white, and blue. They plug into the little circuit board in the upper right hand corner. The yellow and white are being use while the blue is not. It doesn't seem to be of a length to plug in anywhere obvious and, as I said, it may have originally been taped up out of the way. You think?

Thanks. You did a great job.
Brian