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  1. #1
    Join Date
    Feb 2012
    Posts
    59

    Pressure Switch Error

    Comfortmaker was giving pressure switch stuck open error (low). Checked inducer, pulling 2.5", switch closes at 1.5 no problems there. Checked drains and hoses, all clear. By passed pressure switch and furnace fired. Now furnace fired 6 times in a row, no errors. I'm thinking bad pressure switch may be sticking, but I always hate replacing a pressure switch without any other indicators so thought I would see if there were any other opinions. M# c9mpt100j16b1

  2. #2
    Join Date
    Jun 2011
    Location
    Puget Sound area, Wa
    Posts
    130
    restart the furnace, remove the wires from the pressure switch and put your ohm meter on it, make sure its close to zero when closed. sometimes they can also close to quickly but i'm not sure of that pertains to comfort maker

  3. #3
    Join Date
    Feb 2012
    Posts
    59
    Thank you, if it were to read higher ohms, would that indicate a problem with the pressure switch?

  4. #4
    Join Date
    Mar 2012
    Location
    West Haven, CT
    Posts
    41
    HE WANT YOU TO USE THE OHM METER TO CHECK WHEN IT WILL TURN ON AND OFF.

  5. #5
    Join Date
    Jun 2011
    Location
    Puget Sound area, Wa
    Posts
    130
    I've seen them have ohms in the hundreds and that becomes a voltage block, so the board doesn't get a full 24 volts back to the board.
    I'm assuming you are working on a condensing furnace. These furnaces have a knack for the pressure switch tubes getting water in them which corrode the contacts in the switch.

    I don't like to see anything other than 0.0-0.3 on a switch, that's my personal preference though

  6. #6
    Join Date
    Feb 2012
    Posts
    59
    Thanks for the advice, I appreciate it.

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