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Bubba_Bill's avatar
Bubba_Bill
Explorer
Dec 18, 2015

Atwood 8535 III furnace problem?

'95 Damon Intruder. Furnace just quit working, blower ran, no ignition. Motor replaced last year, worked 2 months through Winter O.K. Tested O.K October. Replaced sail switch with 'replacement no.' switch, but paddle slightly smaller. Replaced board with Dinosaur board (figured it was due!), still: blower runs, no ignition, tries to ignite, shuts off, repeats. Open outside door: starts right up! I can close outside door(s) and runs happily. I checked just about everything for mud daubers, nests...you name it. Blew out chamber with compressed air. I'm about to try adding a piece of alum tape to increase size of sail switch paddle. Any ideas Guys? Bill
Class A

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  • Old-Biscuit's avatar
    Old-Biscuit
    Explorer III
    Dec 18, 2015
    That sounds like air intake is blocked/obstructed/restricted.

    And/Or

    Spark electrode out of position.....incorrect gap
  • enblethen's avatar
    enblethen
    Nomad
    Dec 18, 2015
    Could there be a wire pinched in the frame of the door? It could be the ignitor wire that goes across the face.
  • Bubba_Bill's avatar
    Bubba_Bill
    Explorer
    Dec 18, 2015
    MH is in the storage building right now, it's 24 degrees here today! Went down there a while ago and tried something I hadn't before. I loosened the main door screws just enough to allow a crack between the outside main door which apparently left just a tad more air and it started right up....Hhhhm. Got it warm enough to cycle the furnace down to the lowest 50 degree thermostat set ing and left my little electric heater for now 'til it warms up a bit.
  • lasttruck's avatar
    lasttruck
    Explorer
    Dec 18, 2015
    What fault code do you get from the light on the circuit board?

    If the ignitor has a strong, consistent, steady spark (weak may sound ok, but there is a difference). Had that problem on my smaller RV. The ignitor tips may appear fine, but the resistance is within.

    On the PM, the 8940's blower wheel tossed blades twice. Apparently struck the limit switch one time. Sometimes the furnace would run, sometimes not requiring a reset. Replaced the limit switch (relatively inexpensive) and no more problems.
  • jergeod's avatar
    jergeod
    Explorer
    Dec 18, 2015
    Try using a wire through the chamber some of the spider nests are attached so well that air is not going to remove them. (those white fuzzy ones) Just a guess.

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