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  1. #1
    Join Date
    Jul 2002
    Location
    Bellevue WA
    Posts
    82

    Trane UCP troubleshooting

    I had a Trane YCH unit where nothing was running. Power was on, fuses OK, no obvious problems. Following the instructions in the Voyager Microcontrols manual, I checked the UCP LED (it was on), then checked LTB terminals 6-9. There was OvDC, so I installed a new UCP and the unit started.

    Being curious, I checked LTB 6-9 again, and the voltage is still 0. Normal should be 32vDC.

    Am I doing something wrong, or is there still a problem with the unit?

    Thanks,
    John

  2. #2
    Join Date
    Jun 2005
    Posts
    128
    Stupid question - You cycled the power before replacing the board - right?

  3. #3
    Join Date
    Oct 2006
    Location
    TUCSON, AZ
    Posts
    49

    second question......

    like vbhvac said...did you shut down and power up the unit...sounds stupid but it matters..there are a few things that just lock out that UCP, and you will not measure I do beleive any dc volts at those terminals indirectly. What year is the unit?

  4. #4
    Join Date
    Jul 2002
    Location
    Bellevue WA
    Posts
    82
    Yes, I shut it down and restarted it a few times before I replaced the board. The unit was manufactured 09/94.

    It's been working fine for several days with the new board, but LTB 6-9 still doesn't have 32vdc like the book says it should.

  5. #5
    Join Date
    Aug 2004
    Location
    Dupont Pennsylvania
    Posts
    324
    If the unit has an economizer, unplug it and recycle the power. Let me know what you find.

  6. #6
    Join Date
    Jul 2002
    Location
    Bellevue WA
    Posts
    82
    No economizer, it's connected to a Barber Colman system.

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