Fan won't shut off
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  1. #1

    Fan won't shut off

    I have a Keeprite N9MP1075B furnace with a fan that won't shut off. The AC starts and stops as required, I tried the heat as well and it comes on and off no problem, but the fan will run 24/7. The fan switch is on auto, not on, and even tried a different thermostat and had the same results. I have read that I may have a stuck fan relay and try giving it a tap to loosen it up but I can't seem to locate it on my system. I have been told I might have to replace the board as the fan relay may be located there, the circuit board is ST9160B 1084.

    Any help would be appreciated.

    Thank you!

  2. #2
    Join Date
    Sep 2007
    Location
    Boise, ID
    Posts
    4,241
    I can think of 2 other possibilities other than those you mention. Sounds like you need to call a pro.

    Tapping on that relay may get it un-stuck, but then it may not pull in again. Then you got nothing, and will be waiting for a service tech with no AC in the meantime.
    If a nation expects to be ignorant and free, in a state of civilization, it expects what will never be. (Thomas Jefferson 1816)

  3. #3
    Thanks for the reply.

    I actually did call a "pro" and he came in for about 5minutes and told me I need a new board at $. I can get a new board online for about $ and switch it out myself.

    Last night I did some more reading and went back to the furnace, found the fan relay, gave it a slight tap and the fan shut off. So far the AC has running normally with the fan shutting down as it should. It looks as though everything is working fine for now....with the same board. hmmm

    Thanks.
    Last edited by beenthere; 09-06-2011 at 05:24 AM. Reason: prices

  4. #4
    Join Date
    Jun 2011
    Location
    Wake Forest, NC
    Posts
    352
    Fan relays dont typically just stop working once. If it has failed, it will fail again.

    1. Call a pro
    2. Replace the relay.
    3. Enjoy.
    It's not rocket-science...

    It's electromechanical thermodynamic engineering

  5. #5
    Join Date
    Nov 2006
    Location
    Southeastern Pa
    Posts
    17,721
    Quote Originally Posted by runn67 View Post
    Thanks for the reply.

    I actually did call a "pro" and he came in for about 5minutes and told me I need a new board at $. I can get a new board online for about $ and switch it out myself.

    Last night I did some more reading and went back to the furnace, found the fan relay, gave it a slight tap and the fan shut off. So far the AC has running normally with the fan shutting down as it should. It looks as though everything is working fine for now....with the same board. hmmm

    Thanks.
    Unless you work in a profession that routinely uses line voltage components and service, I don't recommend that you as a homeowner replace a board yourself. Here are some observations.

    A board would be the correct repair (assuming the relay is mounted on the board as a permanent component). The fact that you had to tap on a component means that it had bonded electrically where current flows across contacts.

    A board bought on line will not come with a warranty. As a pro, I have made use of many, many parts warranties over the years. Boards are one of a host of parts that do not last as long as similar parts made decades ago. A warranty on a part is a VERY good idea.

    While this may work out for you, there is a risk level that is easily dealt with by working with a pro you trust who is trained and insured for the work, and that protects you AND your home.
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

    RSES CMS, HVAC Electrical Specialist

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