carrier 90% furnace
Page 1 of 2 12 LastLast
Results 1 to 13 of 23
  1. #1
    Join Date
    Feb 2009
    Location
    Oklahoma City, OK
    Posts
    9

    carrier 90% furnace

    Im having trouble figuring out why this 6 year old furnace wont close the pressure switch?

  2. #2
    Join Date
    Feb 2012
    Location
    Toronto Canada
    Posts
    1,090
    Is it stuck open?
    Is the venter motor working?

  3. #3
    Join Date
    Feb 2009
    Location
    Oklahoma City, OK
    Posts
    9
    the venter motor is working and I have replaced the pressure switch

  4. #4
    Join Date
    Feb 2009
    Location
    Oklahoma City, OK
    Posts
    9
    It seems to have to much negative pressure acording to out digital magnehelic guage. we taken off both the flue and freshair intalke and no change

  5. #5
    Join Date
    Feb 2009
    Location
    Oklahoma City, OK
    Posts
    9

    carrier 90% furnace

    Ive replaced the pressure switch and cannot get the furnace to close the pressure switch. any ideas? ive removed the flue and fresh air intake and it did not change any thing.

  6. #6
    Join Date
    Nov 2012
    Location
    PA
    Posts
    47
    Check the vacuum to the switch, maybe the line is plugged up or there is water in furnace due to a plugged drain.

  7. #7
    Join Date
    Feb 2009
    Location
    Oklahoma City, OK
    Posts
    9
    Quote Originally Posted by joeblo View Post
    Check the vacuum to the switch, maybe the line is plugged up or there is water in furnace due to a plugged drain.
    Checked all of that and thats not it. this is a very unusual situation and hard to figure out. Not a typical trouble call!

  8. #8
    Join Date
    Dec 2011
    Location
    San Antonio, TX
    Posts
    381
    Believe it or not, the furnace drain can cause this! The corrugated hoses have to be switched based on left or right flow. They are tagged different colors with description on the panel.

  9. #9
    Join Date
    Feb 2004
    Location
    Ontario
    Posts
    700
    Those corrugated hoses also can crack, and it can be difficult to spot. Be sure to check them.
    Question authority!

  10. #10
    Join Date
    Jun 2012
    Location
    Rising Sun, Maryland, United States
    Posts
    110
    pressure swith could be DOA

  11. #11
    Join Date
    May 2012
    Location
    Upper Michigan
    Posts
    3,588
    What's your pressure compared to the switch? Is it a differential ps?

  12. #12
    Join Date
    Nov 2012
    Posts
    9
    The first thing is how much vacuum the furnace pulls with the intake and exhaust off. The drain could cause this problem. The secondary could be plugged, but this normally trips the roll out. make sure the black intake box under the burners is not plugged with a bird nest etc.

  13. #13
    Join Date
    May 2011
    Posts
    79
    My bet is that there's a gallon of water in the secondary. Good old Carrier drain traps. I have days where I un-clog 3-4 of those in a row.

    Pull the flex hose off the top of the drain trap.

Page 1 of 2 12 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event