Atwood Furnace Problem

Discussion in 'Heating / Cooling Systems' started by Dave M, Dec 20, 2019.

  1. Dave M

    Dave M New Member

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    I have A Park Model Trailer with an Atwood furnace thats driving me nuts.I hear the thermostat click and the blower motor comes on after a minute or two the furnace ignites and everything runs fine.Other times the thermostat clicks blower comes on and after minute or two it doesn`t ignite and shuts off.If I turn the thermostat off wait a couple minutes and turn it back on the furnace will start and run fine.It can run fine for a day and then start acting up again I have replaced the circuit board.This may sound crazy but I have even replaced batteries in the thermostat and sometimes it seems like it will run fine for a day or two and then start acting up again so I`ve replaced batteries and it seems to work fine for a day or two or longer and then start acting up.Worst part is it seems to act up mostly overnight.
     
  2. Raycfe

    Raycfe Waterford Ct.

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    Screen Shot 2019-04-13 at 11.53.58 AM.png
    I would suggest downloading the furnace manual from the web as a first step.
    Checking the exhaust for restrictions and sail switch movement.
     
    tombiasi likes this.
  3. kitphantom

    kitphantom Well-Known Member

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    sail switch? That sounds a lot like the intermittent issue we had a couple of years ago with the furnace in our Retro. We did some research and ordered a sail switch. We were going to order a limiter switch too, but the parts guy at our dealer suggested waiting on that, since the sail switch is a more common problem, ail switch replaced, all has been well since then.
    This was one of the helpful articles I found: https://www.rvtravel.com/troubleshooting-rv-furnace-problems/
     
  4. joet

    joet Well-Known Member

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    Welcome from the Mountains of West Virginia..
    Not that hard to pull the furnace apart. Since you have replaced the board, I would look at switches/flame detector
     
    Last edited: Dec 21, 2019
  5. Fless

    Fless Active Member

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    When this happens is the camper connected to shore power? Using the battery only? Or does it happen with both?

    It could have something to do with how much voltage the furnace is getting, or a blower motor that needs a warmup run before it will spin at the proper rpm on the second try.
    _
     
    Last edited: Dec 22, 2019
  6. generok

    generok Well-Known Member

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    If it is happening when on shore power, you might consider shining a light on the squirrel cage fans and see if you have dust and goop on them. If so, blow and vac it off. It can be just enough to mess with the RPM and airflow to mess with the sail switch.
     
  7. Econ

    Econ Active Member

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    1) What model atwood? 7900 series??
    2) Yesterday my voltmeter went from 12.5 to 11.9 volts when the blower motor cut on. I don't remember the exact voltage but the furnace wont work well if the voltage is too low.( 10 point something volts????) Bad or Weak 12 volt Battery??
    3) did you replace your old board with a cheap Chinese board AKA Atwood OEM board?
    4) just before ignition failure are you hearing a loud click aka the gas valve opening.
    Dont trust this number but the resistance on those are 30k to 50K?????? That is an 18 month old memory.
    5) this will sound strange. Are you in very high humidity?? Are you heating/boiling bath water on the inside in coolish weather. Don't laugh. Moisture on the board. Ask me how I know.
    6) What gauge wire feeding this puppy? Mine's a 10 gauge.
    7) Does yours have and have you read the error code? The code is like flash, wait second, flash, then like a 3 second wait, then repeat. That would be a 2 flash signal.
    8) The limit switch is easy to jump.



    Atwood 7916
    "
    VOLTAGE
    Voltage should be between 10.5 and 13.5 VDC at the
    furnace during operation. The power at the furnace
    needs to be checked with each of the following power
    sources when applicable: generator, battery, and
    converter. Low voltage can cause the furnace to
    overheat and cycle."

    [QUOTE="Dave M, post: 1314879, member: 115064"It can run fine for a day and then start acting up again MOISTURE LEVEL????
    I have replaced the circuit board. OEM CRAP??????

    Worst part is it seems to act up mostly overnight. WEAK BATTERY???????????

    [/QUOTE]
     
  8. Dave M

    Dave M New Member

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    Since I wrote this The heater has been working fine but its done this before.I was checking the unit and noticed the blower wheel cover is broke at the mounting screw holes so its loose.I ordered a new cover and sail switch since it mounts behind the cover Hopefully that fixes it permanatley.
     
    kitphantom likes this.

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