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  1. #1
    Join Date
    Sep 2002
    Location
    Virginia
    Posts
    6,762
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    Why 2 ports on draft inducer switch

    102998-01 is the switch part number

    0.65 WC

    I worked on a Ducane/Lennox 90 % furnace


    Its cutting out flame after about 5 minutes , gives a code 3 ( lost inducer vacuum signal ) then comes back on .. repeat

    I have a switch on order because I checked trap , flue , hoses

    Well it has 2 hoses , one coming off inducer , and other coming out of condensate drain box thingy , both connect to inducer switch

    Why ?

  2. #2
    Join Date
    May 2019
    Location
    Central, IL
    Posts
    34
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    Differential , if everything is clear , I suspect partially plugged/clogged secondary

  3. #3
    Join Date
    Jul 2007
    Location
    Virginia
    Posts
    11,714
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    Post the model number of this unit if you can.

    Also, send me an email, and I will get a pressure switch pdf off to you.

  4. #4
    Join Date
    Jun 2012
    Location
    Northern NV
    Posts
    2,007
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    Has two PS on it, right? One proving the inducer and the other (2 ports) for blocked secondary/plugged drain..

    Had a Ruud that about a thousand bees committed suicide in and ended up in the condensate trap....
    A dying culture invariably exhibits personal rudeness. Bad manners. Lack of consideration for others in minor matters. A loss of politeness, of gentle manners, is more significant than is a riot.
    ― Robert A. Heinlein

  5. #5
    Join Date
    Sep 2002
    Location
    Virginia
    Posts
    6,762
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    Thread Starter
    I don't see the model anywhere , they must have forgotten to slap a sticker on it .

    But its a Lennox with Ducane badge
    Attached Images Attached Images  

  6. #6
    Join Date
    Sep 2002
    Location
    Virginia
    Posts
    6,762
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    Thread Starter
    replaced switch and she runs

    You cant really see , but both red and blue hoses go to the switch

  7. #7
    Join Date
    Nov 2019
    Location
    VA
    Posts
    5
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    Sounds like you have it. next Time, hook up a duel port and see if the switch is making. This can eliminate replacing a good switch. ��

  8. #8
    Join Date
    Mar 2010
    Location
    Arnold, Mo
    Posts
    972
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    I just repaired a Lennox 90% that looks just like your Ducane. The model was ML193UH090XP48C-05. I thought the same thing about the 2 ports. I guess the 2nd port is a blocked drain switch.

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