Forum Discussion

zidjan's avatar
zidjan
Explorer
Sep 06, 2018

2004 Thor 4Winds furnace fan won't shut off

Hi folks,

I wonder if you can point me to the direction on how to diagnose the problem with my furnace.

The furnace is Atwood 8525-II, I am pretty inclined mechanically and handy (amateur - Intermediate) but I have no clue with electrical and furnace in general.

It was working fine and then one day after camping the furnace fan kept going, it didn't pull heat but it won't shut off even after the turn off the thermostat (I shut it off manually with the switch on the furnace). After doing some research I replaced the thermostat to digital but it didn't do anything. So after more reading I am thinking the fan relay but does this particular model integrated with the circuit board?...any thoughts and ideas?
Class C
  • zidjan's avatar
    zidjan
    Explorer
    Sep 11, 2018
    Hi guys,

    Sitrep: I did try put the Thermo at "Auto" but it didn't work fan kept running...So I bought a time delay relay...so do you guys know where it is and how to access it?
  • bobndot's avatar
    bobndot
    Explorer II
    Sep 06, 2018
    zidjan wrote:
    BruceMc wrote:
    If you have a newer unit, check your thermostat's fan setting. It should be on Auto, not high or low.
    I was twiddling with mine some months back when I had the same issue - my thermo was set to low, which means the fan runs all the time.

    Here's a pic of one similar to mine:



    Oh that's interesting, OK I'll play with it tonight and report back..thank you


    Yes, I think 'auto' is the normal position that the thermostat needs to be in. Check the install directions that came with the thermostat that you installed.
  • zidjan's avatar
    zidjan
    Explorer
    Sep 06, 2018
    BruceMc wrote:
    If you have a newer unit, check your thermostat's fan setting. It should be on Auto, not high or low.
    I was twiddling with mine some months back when I had the same issue - my thermo was set to low, which means the fan runs all the time.

    Here's a pic of one similar to mine:



    Oh that's interesting, OK I'll play with it tonight and report back..thank you
  • BruceMc's avatar
    BruceMc
    Explorer III
    Sep 06, 2018
    If you have a newer unit, check your thermostat's fan setting. It should be on Auto, not high or low.
    I was twiddling with mine some months back when I had the same issue - my thermo was set to low, which means the fan runs all the time.

    Here's a pic of one similar to mine:

  • zidjan's avatar
    zidjan
    Explorer
    Sep 06, 2018
    bobndot wrote:
    I'm no expert, I just have this listed in my tech notes that I keep on hand. I have 3 things listed for this. ( no propane, shorted 12v pos wire , TDR )
    The TDR is just something I would try to replace because of the symptom, unless you have a shorted out 12v pos wire.
    If that's the case, try banging on the furnace box itself. A lot of rv mechanics try that because things become loose bouncing down the road. Then they know not to try different parts , wasting time.

    I think you will need to pull the furnace to access the
    TDR .
    Hopefully someone with more experience than I will come to the rescue. I don't want to lead you in the wrong direction and cause you more work if I'm wrong.


    No worries Bob, it's only $25 part...i can gamble with that.
  • bobndot's avatar
    bobndot
    Explorer II
    Sep 06, 2018
    I'm no expert, I just have this listed in my tech notes that I keep on hand. I have 3 things listed for this. ( no propane, shorted 12v pos wire , TDR )
    The TDR is just something I would try to replace because of the symptom, unless you have a shorted out 12v pos wire.
    If that's the case, try banging on the furnace box itself. A lot of rv mechanics try that because things become loose bouncing down the road. Then they know not to try different parts , wasting time.

    I think you will need to pull the furnace to access the
    TDR .
    Hopefully someone with more experience than I will come to the rescue. I don't want to lead you in the wrong direction and cause you more work if I'm wrong.
  • zidjan's avatar
    zidjan
    Explorer
    Sep 06, 2018
    bobndot wrote:
    Did u happen to run out of propane ? If so, you might have to reset it . AFAIK, you do that by pulling the fuse then reinstall it.

    The only other thing I can think of is a relay. I think most DSI models have a time delay relay which has something to do with fans running after the furnace is shut off, but you would need to look into that.


    It wasn't out of propane but the propane was low (1/4) went i realized that the furnace not blowing hot air anymore and went ahead to shut it off from the thermostat and nothing happened.

    I haven't tried pulling the fuse and put it back in to reset it, i'll do that tonight.

    So you kindda agree, the relay is faulty? I can just get the relay and figure it out how to replace it.

    Let me figure out which TDR works with my furnace...i'll report back later
  • bobndot's avatar
    bobndot
    Explorer II
    Sep 06, 2018
    Did u happen to run out of propane ? If so, you might have to reset it . AFAIK, you do that by pulling the fuse then reinstall it.

    The only other thing I can think of is a relay. I think most DSI models have a time delay relay which has something to do with fans running after the furnace is shut off, but you would need to look into that.

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