LP Furnace blew out circuit board panel? SOLVED - See last page!!!

Old Snipe · 09-14-2006, 12:42 PM

Took my 03 Adventurer in for annual service at Camping World. Last year when I used the furnace, it popped every once in a while, but worked fine. I thought it was a little soot build up.

The CW techs found the circuit board was burned out. They installed a new one and it blew out, too. They removed the furnace, bench tested it and everything worked fine. Reinstalled in my MH with a new thermostat assmebly and it blew out the circuit board. Their opinion is a bad wire shorting out the circuit board between the t-stat and the furnace connection. They did a continuity test on the wires and said they checked out okay. That's as far as they will go.

Any ideas?

Thanks!

Old Snipe · 09-14-2006, 12:42 PM

Took my 03 Adventurer in for annual service at Camping World. Last year when I used the furnace, it popped every once in a while, but worked fine. I thought it was a little soot build up.

The CW techs found the circuit board was burned out. They installed a new one and it blew out, too. They removed the furnace, bench tested it and everything worked fine. Reinstalled in my MH with a new thermostat assmebly and it blew out the circuit board. Their opinion is a bad wire shorting out the circuit board between the t-stat and the furnace connection. They did a continuity test on the wires and said they checked out okay. That's as far as they will go.

Any ideas?

Thanks!

RV Wizard · 09-15-2006, 12:39 AM

Check to be sure the 12 volt polarity to furnace is correctly wired. If you must replace yet another board I would recommend the Dinosaur brand. It is fused and has a three year warranty. Find a good repair technician. Most Camping World stores do not have technicians working for them; just installers. www.BryantRv.com has service manuals you can download if you are able to use them. Good luck and let us know what you find to be the problem and fix.

Old Snipe · 09-15-2006, 04:13 AM

Thanks Mike!

Do you have a source of supply for the Dino boards? I like the idea of a fuse. Will check the wiring. Nobody touched the wiring in the first place, so I'm suspecting a wire must have rubbed thru its insulation somewhere in the body. Probably best to run all new wires.

Best Regards!

troth · 09-15-2006, 08:15 AM

Paul, here's the Dinosaur board source:

Dinosaur Boards

Check the two wires coming from the thermostat to the furnace; -they should be low voltage DC, about 3 vdc (certainly no AC).

Old Snipe · 09-15-2006, 09:58 AM

Troth,

Thank You for the info!

Paul

Old Snipe · 09-30-2006, 09:31 AM

Update 9/30/06

Returned from a business trip and my new T-stat and Dinosaur board had arrived. I installed the T-stat and the Dino board, cleaned up the shoddy work from the previous CW tech and...
NO LUCK!

My furnace still does not light and the T-stat controls seem to be working backwards.

I have the a/c heat pump option, it all works, but when I put the switch on Gas, nothing. The dealer I ordered the Dino board from sent me the Fan 50 unit, which fit right in. My furnace is a Suburban SF-42.

I've 2 questions:

What does the little on/off switch by the circuit board do and should it be on, or off for normal running?

If the blue wires on the wire connector (which was cut and respliced together by CW) are reversed, will that cause my problem? Looking at a wiring schematic (Thanks RV Wizard) it appears the blue wires just close the t/stat circuit.

I've made an appointment with my Winnie dealer to look at it in two weeks, but I'm hoping to get an idea to solve the problem before I start paying the $100 per hour charge

to troubleshoot my furnace problem.

Thanks

RV Wizard · 10-01-2006, 01:21 AM

The switch in the furnace needs to be on. What thermostat do you have exactly? What brand of roof air conditioners do you have?

Old Snipe · 10-01-2006, 08:35 AM

Mike,

I have a 2003 Winnie Adventurer with the basement a/c (with heat pump option). The T-Stat is a Coleman Mach, WB Part # 105620-18-000 (Thermostat-Furnace/Heat Pump-A/C).

The two blue wires are in a plastic four pin connector from the t-stat. One of the pins on the t-stat side of the plastic connector is blank (ie only 3 wires coming into it) and one of the 2 blue wires connects into it, a dead connection. The other blue wire, should it go to the circuit board? Its not clear on the schematic, or I'm reading it wrong. I beleive these two blue wires were reversed by the CW tech but I'm afraid to change them unless I'm positive first.

Thanks!

zertrider · 10-01-2006, 03:50 PM

The blue wires can be reversed and not cause a problen, they just close the circuit to each other to turn on the furnace. Neither of the blue wires should have any power to them from the t-stat side, only the board side.
Easiest thing to do here is to remove the cover on the furnace and disconnect the wires that go to the board directly at the furnace. Connect a jumper wire between both blue wires in the connector and then provide 12v power to the red wire. The furnace should then light. If it does, you know that the board or furnace itself is not the problem, and the blue wires to the t-stat may have grounded themselves.
If it does not light, then there is a problem in the furnace itself, and it will have to be remove and checked further.

Old Snipe · 10-02-2006, 03:18 AM

zertrider,

Thank you! I'll give that a try, it is exactly the info I need to narrow this down.

I'll let you know how I make out.

Old Snipe · 10-02-2006, 10:13 AM

Well, I'm really scratching my head now.

I seperated the furnace connector, jumped the two blue wires and applied 12V power from the hot side of the disconnected plug (T-stat side) and the furnace lit right off. So far, so good. At least the furnace is okay.

I then went to the T-Stat (remeber this is a new, exact replacement for the old one) and the 3 wire connector (Hot, Ground and T-Stat) and disconnected one wire at a time, disconnected it at the furnace end and wired a jumper wire in its place, one at a time, to bypass that particular wire. No furnace run. I noticed when I disconnected the Hot wire, there was no power to the T-stat at all. So I guess that wire feeds 12V to both the furnance and the T-stat, even though the schematic shows another 12V feed to the other plug (9 pin) on the T-Stat.

I reconnected every wire back in its correct place, doubled checked the 5 amp fuse on the board (good) and still no furnace run. I hear a click in the T-stat when I put the setting to gas heat and run the temp thermometer up at least 10 degrees over room temp.

I even ran an extra ground wire to the furnace from the frame, just in case, no joy. I pulled on the wire harness behind the T-sat into the wall and again the harness going into the furnace in case I could reposition a shorted wire somewhere in the wire run.

I am stuck now big time and am afraid the only thing I have left is open my wallet and kiss my money good-bye! Any last minute ideas would be appreciated. Where else can you have so much fun and spend all the kids inheritance (LOL)?

Thanks!

RV Wizard · 10-03-2006, 12:14 AM

Paul, It sounds like you have either a broken wire between the furnace and T'stat or a bad T'stat. If you have some wire run two news ons around walls to furnace just to test. It the furnace now works you will need to find where the break is and try to repair or run new
wire(s)permanately. Good luck and keep us informed as to what you find.

Old Snipe · 10-04-2006, 12:51 PM

I kept telling myself it had to be something simple, it was!

I obtained a schematic and checked everything out. Everything seemed odd, so with nothing left to try, I switched the two blue wires at the furnace that the CW tech had originally cut, no joy, so I switched them back.

The wires are a very thin gauge, (14-16) and the tech had connected them with blue butt connectors. When I reconnected them, I used the correct size red butt connectors and the Furnace lit right off. I cycled it several times and ran it for a while, it heated up and shut off properly. PROBLEM SOLVED! The CW tech used the WRONG SIZE size butt connectors and NEVER ESTABLISHED A GOOD CONNECTION!!!

I was really frustrated, but with all you folks giving me advice and encouragement, I stuck with it. Glad I did. Not only did I save myself some serious money, but I now know my furnace inside and out.

Mike (RV WIZARD), troth and zertrider, if you ever get down to the Washington, DC area, let me know, I'm buying you a great dinner!

Thanks again! I appreciate your help.

Best Regards!

RV Wizard · 10-04-2006, 04:38 PM

Paul, glad to hear that youhave found and repaired the problem. Thank you for posting back as to the fix. I am glad it was simnple and that we could help. Good luck and stay in touch.

zertrider · 10-07-2006, 08:49 AM

Just pass on the help to someone else and that's thanks enough. I can't see me ever making it to DC anyways.