Carrier Furnace..any ideas? - Page 2
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  1. #14
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    Oct 2012
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    Sacramento,ca
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    Quote Originally Posted by coolwhip View Post
    Rarely have I seen a pressure switch go bad, especially on a 7 year old furnace.
    really? every one i have ever replaced has been on newer system and under warranty particularly goodman units.

  2. #15
    Join Date
    Feb 2007
    Location
    Fremont, Indiana
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    1,407
    Seems to me I have run across many a bryant/carrier with slow drain (clog somewhere) cutting out ps on long runs. Only to clear when tech shows up and runs through cycles.
    I would start looking at slightly choked secondary/trap

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  3. #16
    Join Date
    Jun 2006
    Location
    Richmond, VA
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    Quote Originally Posted by kamersoutdoor View Post
    Seems to me I have run across many a bryant/carrier with slow drain (clog somewhere) cutting out ps on long runs. Only to clear when tech shows up and runs through cycles.
    I would start looking at slightly choked secondary/trap

    sent from my Samsung Galaxy Note
    x2

    Did one this afternoon, started right up while I was there and ran for 20 minutes before it dropped out..condensate coming out thru the drain the whole time, just not enough. Along with the bugs and leaves in the intake didn't help much.
    Give a man a fish, he will eat for a day. Teach a man to fish, he will eat for a lifetime.

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  4. #17
    Join Date
    Jul 2009
    Location
    Columbia, MD
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    3,783
    Look for a clogged trap. U say flue pipe is only 8'? This could cause to much static on trap and not allow it to drain

  5. #18
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    Feb 2004
    Location
    Ontario
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    700
    Do you have model and serial numbers?
    Question authority!

  6. #19
    Join Date
    Oct 2012
    Location
    Sacramento,ca
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    196
    went back today because it was not sitting well with me. Got there running fine no problems on high heat (3 days since last visit). What I discovered after looking closer is that the 2nd stage pressure switch closes fine but doesn't open all the way sometimes after inducer shuts down and the board checks this before startup and that's why it would lock out on a pressure switch code especially if the furnace tried to restart within 30 mins or so. I never caught this because the unit would be off for hours before I got there and the switch would be open by then. The reason I didn't have issues after i jumpered w-1 & 2 is because the PS2 was already closed on startup and that doesn't cause a code apparently. Thanks for all the help. I don't run across many carriers so this was a new one for me.

  7. #20
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    Jul 2009
    Location
    Columbia, MD
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    Good Job!

  8. #21
    Join Date
    Feb 2004
    Location
    Ontario
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    700
    My own Carrier MVP is about 8 years old now. It exhibited the same symptoms you've described for most of one winter and drove me nuts. Showed a pressure switch code, but I could never find a fault. I changed the venting all around, replaced switches, considered wind effects etc etc, and then one day saw a remark on this site that there were some bad boards, known to Carrier, that were causing this exact intermittant problem. I changed the board and have never had a problem since.

    Unlikely that this would apply to your case if your furnace has been operating well for several years previously, but still something to keep in mind.
    Question authority!

  9. #22
    Join Date
    Nov 2011
    Location
    St. Louis
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    3,166
    Quote Originally Posted by Barrettservices View Post
    went back today because it was not sitting well with me. Got there running fine no problems on high heat (3 days since last visit). What I discovered after looking closer is that the 2nd stage pressure switch closes fine but doesn't open all the way sometimes after inducer shuts down and the board checks this before startup and that's why it would lock out on a pressure switch code especially if the furnace tried to restart within 30 mins or so. I never caught this because the unit would be off for hours before I got there and the switch would be open by then. The reason I didn't have issues after i jumpered w-1 & 2 is because the PS2 was already closed on startup and that doesn't cause a code apparently. Thanks for all the help. I don't run across many carriers so this was a new one for me.


    I've never met a furnace that didn't throw a code if a PS was closed upon start up.

  10. #23
    Join Date
    Oct 2012
    Location
    Sacramento,ca
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    196
    Quote Originally Posted by hurtinhvac View Post
    [/B]

    I've never met a furnace that didn't throw a code if a PS was closed upon start up.
    I just reread that sentence and realized that it does not make any sense. Long day i guess

    Unit will not start unless both switches are open. Low heat caused high heat switch to stick closed after shutdown for a period of time for some reason. whereas high heat only wouldn't cause the switch to stick. Sorry for the confusion.

  11. #24
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    Feb 2010
    Location
    butler pa
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    1,073
    Quote Originally Posted by gravity View Post
    Look for a clogged trap. U say flue pipe is only 8'? This could cause to much static on trap and not allow it to drain
    i seem to recall install instructions when horizontal vented thru roof a min 12" horizontal section before termination

  12. #25
    Join Date
    Jan 2013
    Posts
    45
    It's the pressure switch I've replaced 4x already this winter season in northern VA pretty much on carriers..also have a magnihilix to test it while running to see what the pressure are

  13. #26
    Join Date
    Nov 2011
    Location
    St. Louis
    Posts
    3,166
    I'm not sure where this notion of pressure switch immortality came from. My boss is leary everytime a tech orders one. The very first one I went to replace was condemned by another tech. Boss told me to check the system again before you replace it so I teed in the manometer, metered across the switch and just that easily saw it was not making with plenty of tenths of inches of water column to spare. Replaced switch and all has been well ever since.

    Last call of the day yesterday was a Kelvinator throwing a PS error. Out comes the manometer and voltmeter. Pulling 1.26, switch makes at .55 and I have both legs of power on either side of the switch. It's open when it should be closed. Bad switch.

    Back in January I had another one...a Carrier. Same routine only this time, as it happens fairly often, after I jostle the switch in the process of teeing in and checking for condensation crud in the ports, the integrity of the connecting hoses etc. the switch starts behaving again. I told the guy it was stuck, it may or may not stick again, I have no way of telling if or when but I would bet on eventually. He declines to replace it. Three weeks later a 30 year tech goes back with new switch in hand (as well as the ignitor I suggested replacing as it was getting bright white with the slightist little stress line and measuring way over 100 ohms) as it had failed agin. This tech found a piece a crud stuck in one of the ports and completely blew off my findings...just cleared the port and went on his way, not replacing anything or charging the customer anything, just assuming his experience completely negates mine. This results in a love note in my tech folder. Now I can easily see an obstruction in a port a few weeks down the road after I checked them, makes perfect sense to me; I've come accross many an obstructed port and cleared them easily. It only takes one piece of white, crusty condensation anywhere near the port to get sucked in. But that was not the issue when I was there as it would have shown on my manometer even if I was to have visually missed it. I'm betting we will be back there before the end of the season for the same issue, and perhaps again for an ignitor. BTW, the white stuff should be a clue to check the gas pressure and make sure it's burning hot enough.

    Pressure switches can and do go bad, and it seems to me, even after only a couple of years in the field; that their failure rate is increasing. More often it is some kind of obstruction, cracked hose or other issue and the PS is simply doing it's job; I completely agree. However sometimes the damn things just fail like anything else. But you absolutely need an instrument to measue the inches of WC and be able to confirm the switch is actually making or not. I get the feeling a lot of techs are just winging it or making assumptions. Otherwise why all the confusion surrounding these rather simple switches?

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