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  1. #1
    Join Date
    Feb 2001
    Location
    Jackson, NJ
    Posts
    92

    Furnace Problems - The Legend Continues

    All: If you check my previous posts, you'll see that I've been having ongoing problems with my forced air furnace, primarily related to the limit switch. I believe that the problem with the limit switch may have been resolved, but another problem has cropped up. Here's a brief description of the problem: the fan continues running even after the limit temperature has been met for either zone. The thermostats are set on "auto". Sometimes the fan will run all day even though neither zone is calling for heat, and the fan will not shut down until the next heating cycle when the fan stops and then starts again. This time I checked the indicator light on the control board, and it indicated that the pressure switch was open.

    Here are my questions: 1. What is a pressure switch? 2. Does the "pressure switch open" indicate that there's a problem? Will replacing the pressure switch resolve the problem or is there something else that the tech should be checking?

    In prior posts I indicated that the problem was with the limit switch, but this time the indicator light didn't show that the problem was related to an open limit switch. To deal with the limit switch problem we had the supply and return ducts enlarged, added another return duct, and added a by-pass damper to dump the excess air into the basement. So far, the house is uniformly warmer, and I can't tell if the furnace is short cycling...it appears to be cycling normally except as noted above.

    Thanks for the information.

  2. #2
    Join Date
    Dec 2002
    Location
    Toledo, Ohio, United States
    Posts
    12,896
    Twilli, against the rules Twilli might add has directed you to an instructional video.


    No Heat No Cool You need Action Fast

  3. #3
    Join Date
    Feb 2001
    Location
    Jackson, NJ
    Posts
    92

    Instructional Video

    Mr. Twill: Very educational video. Thanks for the information.

  4. #4
    Join Date
    Jan 2007
    Location
    Arkansas NWA
    Posts
    33

    Pressure Switch

    When the fan continues to run like you say usually means the furnace has tripped on a safety switch. You need to run it through a heating cycle and determine what the problem is.
    Good Luck!

  5. #5
    Join Date
    Dec 2002
    Location
    Toledo, Ohio, United States
    Posts
    12,896
    Quote Originally Posted by eapples View Post
    Mr. Twill: Very educational video. Thanks for the information.

    Twilli is always glad to help.
    No Heat No Cool You need Action Fast

  6. #6
    If it says its an open pressure switch you need to have your flue checked out. And make sure your inducer motor is running.

  7. #7
    Join Date
    Aug 2007
    Location
    MN
    Posts
    2,677
    Quote Originally Posted by eapples View Post
    All: If you check my previous posts, you'll see that I've been having ongoing problems with my forced air furnace, primarily related to the limit switch. I believe that the problem with the limit switch may have been resolved, but another problem has cropped up. Here's a brief description of the problem: the fan continues running even after the limit temperature has been met for either zone. The thermostats are set on "auto". Sometimes the fan will run all day even though neither zone is calling for heat, and the fan will not shut down until the next heating cycle when the fan stops and then starts again. This time I checked the indicator light on the control board, and it indicated that the pressure switch was open.

    Here are my questions: 1. What is a pressure switch? 2. Does the "pressure switch open" indicate that there's a problem? Will replacing the pressure switch resolve the problem or is there something else that the tech should be checking?

    In prior posts I indicated that the problem was with the limit switch, but this time the indicator light didn't show that the problem was related to an open limit switch. To deal with the limit switch problem we had the supply and return ducts enlarged, added another return duct, and added a by-pass damper to dump the excess air into the basement. So far, the house is uniformly warmer, and I can't tell if the furnace is short cycling...it appears to be cycling normally except as noted above.

    Thanks for the information.
    venting problem, or drain, or inducer problem, or switch problem, or cracked hoses, or....

    should be a simple problem for your tech to solve, also could have cracked your heatexchanger due to bumping limit too many times.
    You can't fix stupid

  8. #8
    Join Date
    Dec 2002
    Location
    Toledo, Ohio, United States
    Posts
    12,896
    Twilli wonders??????


    No Heat No Cool You need Action Fast

  9. #9
    Join Date
    Feb 2001
    Location
    Jackson, NJ
    Posts
    92

    Thanks for the Information

    Thanks to everyone, including Mr. Twill (why I don't know), for the information...I'll let you know how it turns out.

  10. #10
    Join Date
    Apr 2004
    Location
    MN
    Posts
    1,781
    twilli funny!
    A Veteran is a person, who at some point in their life, wrote a blank check payable to the United States of America for payment up to and including their life.
    Gene Castagnetti-Director of the National Memorial Cemetery of the Pacific in Hawaii

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