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  1. #1
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    Apr 2019
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    Trane tuy 90% furnace pressure switch code as soon as powered up

    Have a Trane tuy080 90% gas furnace horizontal left.

    Model # TUY080R9V3W6

    Original issue was found while performing combustion analysis and had high oxygen but all other measurements were within NCI parameters

    Found secondary heat exchanger collector box cracked. Which sits in behind inducer assembly so had extra oxygen mixing after combustion.

    Long story short system has age on it I did my best to set up comfort consultant lead but customer insisted on replacing heat exchanger due to it having lifetime warranty.

    Of course doing a 90% split furnace you have to totally disassemble the furnace wiring , burner box gas valve manifold and inducer assembly. So Iím always safe when it comes to wiring and took pictures to make sure I knew where all wiring went when I put everything back together.

    Swapping H.E. Went well. Wired unit back up also installed new burners as it needed them. Get everything buttoned up and go to power system on to make sure everything was operating properly.

    As soon as I give furnace power it immediately flashed 3 red blinks which is pressure switch issue. ( love how Trane doesnít give you more information other than ISSUE) checked switch and itís a NO switch which of course was open. Furnace doesnít even start inducer so Iím going out on a limb and guessing that 3 red blinks is switch stuck closed ,again I know itís open by using my multimeter on ohms
    Only thing I can make work is the indoor variable blower.

    Any ideas before I go beating my head against the wall. Will probably go back to this customer tomorrow.

    So any ideas would be greatly appreciated


    Sent from my iPhone using Tapatalk

  2. #2
    Join Date
    Jun 2017
    Location
    Portland, OR(Previous: Arizona, Texas, Oklahoma)
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    Quote Originally Posted by Dhumphries82 View Post
    Have a Trane tuy080 90% gas furnace horizontal left.

    Model # TUY080R9V3W6

    Original issue was found while performing combustion analysis and had high oxygen but all other measurements were within NCI parameters

    Found secondary heat exchanger collector box cracked. Which sits in behind inducer assembly so had extra oxygen mixing after combustion.

    Long story short system has age on it I did my best to set up comfort consultant lead but customer insisted on replacing heat exchanger due to it having lifetime warranty.

    Of course doing a 90% split furnace you have to totally disassemble the furnace wiring , burner box gas valve manifold and inducer assembly. So Iím always safe when it comes to wiring and took pictures to make sure I knew where all wiring went when I put everything back together.

    Swapping H.E. Went well. Wired unit back up also installed new burners as it needed them. Get everything buttoned up and go to power system on to make sure everything was operating properly.

    As soon as I give furnace power it immediately flashed 3 red blinks which is pressure switch issue. ( love how Trane doesnít give you more information other than ISSUE) checked switch and itís a NO switch which of course was open. Furnace doesnít even start inducer so Iím going out on a limb and guessing that 3 red blinks is switch stuck closed ,again I know itís open by using my multimeter on ohms
    Only thing I can make work is the indoor variable blower.

    Any ideas before I go beating my head against the wall. Will probably go back to this customer tomorrow.

    So any ideas would be greatly appreciated


    Sent from my iPhone using Tapatalk
    Sounds like you miswired it after you installed the heat exchanger. Did you pull out the schematic after you got that error code?

    There could obviously be something else wrong but that would be the first thing I'd do if that happened to me. We all make mistakes

    Sent from my LM-G710VM using Tapatalk

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  4. #3
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    Apr 2019
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    Thread Starter
    Quote Originally Posted by FreeThrowGuy View Post
    Sounds like you miswired it after you installed the heat exchanger. Did you pull out the schematic after you got that error code?

    There could obviously be something else wrong but that would be the first thing I'd do if that happened to me. We all make mistakes

    Sent from my LM-G710VM using Tapatalk
    Yes I double checked with schematics. After 1.5 hours of racking my brain and double and triple checking schematics I had to pull off for the day. Iím clearing my head of it and going back tomorrow with fresh set of eyes and perspectives.

    Definitely will quadruple check wiring again.


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  5. #4
    Join Date
    Aug 2018
    Location
    Piedmont Triad, NC
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    An inducer that is locked up or has open windings will throw a code like that. Maybe a broken wire leading to inducer or some foreign object fell in while it was apart.

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  7. #5
    Join Date
    Apr 2019
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    Thread Starter
    Quote Originally Posted by Achso017 View Post
    An inducer that is locked up or has open windings will throw a code like that. Maybe a broken wire leading to inducer or some foreign object fell in while it was apart.
    I will definitely check that thanks


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  8. #6
    Join Date
    Jul 2007
    Location
    Virginia
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    I'm guessing you tested both pressure switches to see if they were "OPEN"?

    Just to be sure, I would pull the one lead off each pressure switch and see if the inducer starts.

    Is there actually power to the inducer on a call for heat?
    Instead of learning the tricks of the trade, learn the trade.

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  10. #7
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    Apr 2019
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    Thread Starter
    Quote Originally Posted by rundawg View Post
    I'm guessing you tested both pressure switches to see if they were "OPEN"?

    Just to be sure, I would pull the one lead off each pressure switch and see if the inducer starts.

    Is there actually power to the inducer on a call for heat?
    Yes checked both and they are open. Inducer never starts.

    And honestly didnít verify power to inducer.


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  11. #8
    Join Date
    Aug 2002
    Location
    Southold, NY
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    Wasn't that the model that wanted to see closed pre-inducer then open to prove ?

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  13. #9
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    Apr 2019
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    Thread Starter
    Quote Originally Posted by pecmsg View Post
    Wasn't that the model that wanted to see closed pre-inducer then open to prove ?
    Not 100% sure


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  14. #10
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    Virginia
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    Quote Originally Posted by pecmsg View Post
    Wasn't that the model that wanted to see closed pre-inducer then open to prove ?
    The installers guide states:

    After the control module has verified that the 1st stage pressure switch contacts are open and the limit switch(es) contacts are closed, the draft blower will be energized.
    Instead of learning the tricks of the trade, learn the trade.

  15. #11
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    Aug 2002
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    Southold, NY
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    Quote Originally Posted by rundawg View Post
    The installers guide states:

    After the control module has verified that the 1st stage pressure switch contacts are open and the limit switch(es) contacts are closed, the draft blower will be energized.
    OK that's it ...............open then closed!

  16. #12
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    Apr 2019
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    Thread Starter
    Only problem is inducer never starts no matter what I do.


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  17. #13
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
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    What's the inducer? ECM with the square motor or 3 phase with the round motor? Probably the former unless it has been upgraded. That's a symptom of an inducer problem and you have to get a kit to replace inducer, board, wiring harness & ignitor to get rid of the square head motor.

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