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36535Re: Anybody out there work on their Suburban furnace?

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  • tom
    Mar 2, 2012
      Houston, we have ignition and lift off!
      But, luckily no explosion

      Thought I would give and update. Reinstalled the furnace yesterday after I'd done about everything I could do-with a huge amount of help from Docrocker Thanks Todd. I owe you a few cold ones if you ever get to NE Ks.

      This old girl only has 26k on it and spent most of its life under roof. The major problem was probably just sitting.

      We think cleaning the contacts on the board where the plug from the Tstat goes might have been a major contributor. After removing the board, the foil contacts can be cleaned with a red pencil eraser.
      The other thing I did was adjust the ignitor contact a little closer to the center electrode. It should be 1/8 - 1/32 according to doc.
      Before reinstalling any component, contacts were clean and shiny. I also removed the burner and cleaned it up by running a hack saw blade through the slots to clean the rust off, wire wheeled the rest and blew it out with compressed air.

      One other thing I noticed, there isn't a lot of clearance between the sail switch arm and the opening in fan box. Make sure tab isn't bent and the arm hanging up.

      There ain't much room to diagnose this thing without pulling it. At least I don't see how it could be done.

      I was about to take it in to an RV center, as another forum about scared me out of working on it. But, on a limited budget, just couldn't deal with shelling out several $100 to have them look at it.
      Doubt they like dealing with antiques anyway. I figured, what the H---, I ain't out anything and can always take it in if no success.

      Sorry for the long post. But, the wife will be happier the first time we take it out.
      Thanks all for help and replies.
      Tom B


      --- In classicrv@yahoogroups.com, "RogerD" <red2dog45@...> wrote:
      >
      > Good comments here - lots of information about Suburban furnaces.
      >
      > As you have both gas feed and ignition failure, seems the advice on checking the control system is correct. Chances of the gas valve and the ignitor both failing on their own is unlikely.
      >
      > Don't think that an RV repair shop will always solve your problem. I took my rig to a dealer in eastern Pennsylvania for repair to a furnace like yours. Big shop with lots of RVIA technician certs on the wall. Got it home and it still would not fire. They swore it worked in the shop, but made the comment it needed more gas pressure (what!!!). Sure did, as I found the gas nozzle clogged by a piece of crud! You can't diagnose anything without removing the cover, and they never even took it out to do that (10 minute job). Board tester? Hah - don't count on a shop having one. Ask around.
      >
      > If you do have to replace the board, I would recommend the improved ones from Dinosaur Electronics. Their standard board (UIB S) will make three tries to ignite then lock out. If you use the furnace on 12 volt only overnight, their Fan 50 Plus board will also shut off the blower after the three tries without ignition. Comes in handy if you run out of propane unattended. The factory board (at least older models) will keep trying to start, and suck your battery dry because the blower will keep running. Any RV parts seller can get these.
      >
      > http://www.dinosaurelectronics.com/Ignitor_boards.htm
      >
      > Roger
      >
      > --- In classicrv@yahoogroups.com, "tom" <TBBahner@> wrote:
      > >
      > > Hi all, the Suburban NT30m furnace in the old '82 Cross Country doesn't want to fire.
      > > Fan runs, no gas, no ignite. Full tank of propane.
      > > Want to try to fix it myself but don't want to blow up the coach or myself. Should I do it myself or take it to an RV center and fork over the bucks.
      > > I've pulled it out, sail switch appears to work when moved manually.
      > > Any info appreciated.
      > > Thanks
      > > Tom B
      > >
      >
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