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  1. #1

    Brand new Goodman GMH950904CX runs for 10 minutes and then flashes 3 diagnostic light

    We have a new Goodman GMH950904CX that was just installed. It is installed in the basement for upflow. When the HVAC tech installed the furnace, the furnace was tilted slight to the front which is correct, but the furnace is not level with left side higher than the right side.

    The tech used the drain hole on the left side. The furnace would stop after 5 minutes. I changed the drain tube to the right drain hole and now the furnace would operate for at least 15 minutes. The weird thing is that it would shut off intermittently and flash 3 diagnostic flashes and would not restart. Turning off the unit and powering back on it would run for another 15+ minutes.

    I checked the drain and there is no back flow or clog in drain. The exhaust pipe is draining fine and the 2nd heat exchanger is draining fine. I left the front cover off and this still happens so most likely not a fresh air supply problem.

    I am stuck!

    Does anyone have any suggestion? Could a new furnace have a bad pressure switch? Is that common? Also, the furnace was in the basement for about 3 months during construction. Would the dust have possibly clogged up something in the furnace? or clogged up the pressure switch?

    Please help!

  2. #2
    Join Date
    Feb 2006
    Location
    USA
    Posts
    4,365
    Call back the people that installed it.

    Sent from my SGH-T999 using Tapatalk 2

  3. #3
    Join Date
    Jan 2008
    Posts
    1,858
    Your work on the furnace may void the installers responsibility.
    I would leave it alone and call the installer.
    "Hey Lama, hey, how about a little something, you know, for the effort." And he says, "there won't be any money, but when you die, on your deathbed, you will receive total consciousness." So I got that goin' for me, which is nice. - Carl Spackler

  4. #4
    Join Date
    Dec 2010
    Location
    WV
    Posts
    114
    what is the exhaust vent size? how many elbows? how many feet?

  5. #5
    Quote Originally Posted by SuperTech2010 View Post
    what is the exhaust vent size? how many elbows? how many feet?
    9ft with 5 elbows 2" pipe

  6. #6
    Join Date
    Dec 2010
    Location
    WV
    Posts
    114
    Quote Originally Posted by sho1sho1 View Post
    9ft with 5 elbows 2" pipe
    install manual says that this is acceptable, 20ft with 5 90's is what i am reading...is it lock out with 3 flashes? meaning open pressure switch during call for heat? it is working for a short time, so we are working until what happens? is this set up for 2stage auto, or 5min? i would look for somewhere water is pooling in the exhaust. did u pull the draft inducer off and check for small PVC shavings(i have found this a lot) getting into tubing. i am betting that there is no problems with the pressure switches, its doing this for a reason...

  7. #7
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    24,946

  8. #8
    Join Date
    Dec 2010
    Location
    WV
    Posts
    114
    got ya jp...thanks

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