Is this bad limit switch bad because if water damage?
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  1. #1

    Is this bad limit switch bad because if water damage?

    I have this limit switch that went out in my trane xr90 furnace. It appears it is rusty and damaged from a previous water leak the furnace had. Can someone verify this for me by looking at the attached photo? Thanks
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  2. #2
    Join Date
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    Quote Originally Posted by Steve3258 View Post
    I have this limit switch that went out in my trane xr90 furnace. It appears it is rusty and damaged from a previous water leak the furnace had. Can someone verify this for me by looking at the attached photo? Thanks
    The thermal overload should not be effected by rust. The sensor itself on the end is Stainless Steel and what you see as an orange color is a thermal covering for the wire.

  3. #3
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    The brown color is usually the reaction of the covering to heat, not moisture. Looks more like heat than moisture changed the color of the protective cover. I've actually seen these go nearly black if really overheated!

  4. #4
    Thanks for the replies. I was told it went bad because my filter was too dirty, however I was told to change the filter twice a year and as long as I can see some daylight through it I should be fine. But now this limit switch went out after we had a water leak and some other parts including the flame roll out switch are rusted and corroded so I was thinking the water leak was likely the cause of the limit switch as well

  5. #5
    Add pic
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  6. #6
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    Quote Originally Posted by Steve3258 View Post
    Thanks for the replies. I was told it went bad because my filter was too dirty, however I was told to change the filter twice a year and as long as I can see some daylight through it I should be fine. But now this limit switch went out after we had a water leak and some other parts including the flame roll out switch are rusted and corroded so I was thinking the water leak was likely the cause of the limit switch as well
    not a good recommendation. change them every 30-60 days. I think it's time for a thorough inspection by a trained pro. what was the water leaking from?

  7. #7
    Quote Originally Posted by snupytcb View Post
    not a good recommendation. change them every 30-60 days. I think it's time for a thorough inspection by a trained pro. what was the water leaking from?
    The recommendation was guven to me by a trained pro and this was supposed to be a thorough inspection by the same trained pro the water leak was down the whole side of the furnace from a bad install by the same company who then came out to correct the problem but the leak only became worst now I'm dealing with rusted and corroded internal parts that the company does not want to fix without over charging me of course. But thNks for the information as I'm sure this will all come in handy

  8. #8
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    - use cheap filters and change them monthly
    - plugged filters causes frequent cycling of the high limit switch and eventual failure
    - water can cause a high limit switch failure but it has to hit/fill the switch mechanism directly
    - the color shown in the picture is heat related, not rust
    ~~
    Nest is poo...

  9. #9
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    unless it's a media filter or the furnace rarely gets used, 2 times per year is generally not a good recommendation. maybe you have different circumstances. waiting until you can't see through it is not a good idea. it's not a timer. the point is to filter the air, if no air gets through it's not filtering anything and will damage components. some cheap. some very expensive. how old is the unit?

  10. #10
    Quote Originally Posted by snupytcb View Post
    unless it's a media filter or the furnace rarely gets used, 2 times per year is generally not a good recommendation. maybe you have different circumstances. waiting until you can't see through it is not a good idea. it's not a timer. the point is to filter the air, if no air gets through it's not filtering anything and will damage components. some cheap. some very expensive. how old is the unit?
    the unit was installed new in 2007

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