SF-30 Furnace troubleshooting

[Canadiantwig]

Hey,

Bought a used 2004 Cougar recently. The SF-30 furnace was painfully loud and actually vibrated the trailer. Living in the unit and I’d watched videos and checked other forums on troubleshooting. Unfortunately now it’s dead. It clicks when you turn it on at the thermostat and that’s it. Originally I figured the fan was gummed up causing it to be off balance. Due to the way they’re installed, I’m hesitant to just yank it out. It looks like I’ll have to cut the electrical wires in order to pull it out. Also disconnect the propane.

Looking for advice on troubleshooting. I’ve read some about maybe the supply of propane isn’t enough and I’d like to check that but unsure how. It did “die” the day after I filled the propane tanks.

Also who has pulled one out? I’m not so worried yet about the after I get it out. It’s the how the fawk do I get it out I’m worried about.

And go... :/

[chuckster57]

Welcome to the forum!!

Remove the return grill inside the trailer. It will be easier to put back in if you remove the 2 exhaust ports on the outside.

Yeah you’ll need to cut the 4 wires, just cut them before the connectors so you can match the colors. There may be 2 blue wires and it’s not mandatory to put those back to the same one, just blue to blue.

Then turn off the LP at the cylinders. Use 2 wrenches to remove the line so you don’t damage anything. The ducts just need to be rotated to line up a tab and slot. With the front cover off to undo the gas line you should see 2 screws holding the furnace in place. Take those out and the whole thing should come out.

The 4 wires are
12V positive ( usually red)
12V negative (usually white)
Thermostat signal (usually blue)

Once out, if you supply 12V to the unit and jump the 2 blue wires together, you should hear the fan start running. If not then you need to start taking it apart.

[Roscommon48]

your getting into an area where you need to know what your'e doing. try new propane tanks and if not get to a service center.

and yes, rv furnaces are loud! get an electric heater to help assuming you are on electric.

[Customer1]

If the fan doesn't run it has absolutely nothing to do with the propane.

Follow Chuckster57's advice. If lucky you'll find something jammed the fan, if not you'll need to replace the fan/motor.

[Canadiantwig]

Got it out, still only clicks when tested on 12v �� Guess it’s time to start dismantling/watching more videos.

Any input would be great

[chuckster57]

What clicks? Have you tried spinning the fan by hand?

[Canadiantwig]

Okay, so I did a bunch of things. Got it out, hooked to 12v and only clicks. Held up the sail switch and got more effort from the machine to try to ignite. A few phone calls, some compressed air to blow it out and a wiggle on the wires and she fired up perfect. Ok this is a fluke! Tried it three more times and it worked like a charm. Put the cage back around it... back to just the click. So now I’m guessing something is loose or what.

[chuckster57]

With the cage put back together, does the fan spin by hand?

[Canadiantwig]

Yep spins freely

[JRTJH]

If you don't have it, you can download the Suburban Furnace Repair Manual here: http://www.bdub.net/manuals/Suburban_Service_Manual.pdf

Take a look at the "sequence of operation" on page 23. Based on your description, I'd suspect a bad relay or a bad connection in the wiring from the thermostat to the control board and/or from the control board to the bi-metal initiation relay. If that relay doesn't close, the fan will not receive power. If, what you're hearing is the "coil in the relay clicking" but the fan doesn't start, that relay could be "hanging" and not making contact to start the fan motor, which would shut down the sail switch/air flow and cancel the ignition sequence.

[Canadiantwig]

Decided to try and order a 521099 control board. Seems to be everything works unless it goes through the existing board.

[chuckster57]

Originally Posted by Canadiantwig

Decided to try and order a 521099 control board. Seems to be everything works unless it goes through the existing board.

It might be too late, but if you haven’t ordered it yet get a Dinasour brand board, much more reliable than the OEM.

[Canadiantwig]

I did get a dinosaur. I’d seen the comments about them and the closest place had them. He was great actually, was going to let me return it if that wasn’t the problem.

Thanks for all your help! I made a few adjustments, like making the wiring long enough so you can pull the unit out and still be hooked up (not to propane). I haven’t quite secured it back in place but she purrs. Guessing the huge dead moth was the thing causing all the noise.

Going to go read up on hot water tanks now, I think someone already posted my exact problem.