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  1. #1
    Join Date
    Mar 2012
    Location
    Grand Prairie, TX
    Posts
    27

    Trane YCD240 rooftop unit troubleshooting help!!!

    I'm working on a Trane YCD240 RTU. this unit had been turned off for very long time 3+ yrs. Now customer need it. here is the problem
    Unit got correct power going to it, turned it on. It will not do anything, nothing run. LED light on the control board lit up. Shorted Test1 + Test2 for test mode, but it will not do anything... Checked voltage across test1 and TEst2 got 1.9 VDC. (it should be around 5 vdc). Checked wiring, all seem ok...I'm guessing control board is bad... what do you think? need help..

  2. #2
    bad board

  3. #3
    Join Date
    Feb 2011
    Location
    Chesterfield, Virginia, USA
    Posts
    84
    Does it have anything attached to its "Emergency Stop" terminals? And if yes have you tried jumping them out?

  4. #4
    Join Date
    Jun 2006
    Location
    midwest
    Posts
    126

    board

    Disconnect J6 plug and try test mode and check LTB 16+17 for emergency stop.

  5. #5
    Join Date
    Oct 2005
    Location
    USA
    Posts
    396
    does the unit have pressure? Maybe one of your safeties is open
    RTFM!!!

  6. #6
    Join Date
    Feb 2010
    Location
    IL
    Posts
    124
    should still run at least heating or cooling if only 1 safety is open... I.E. 2nd stage high pressure open and non of 1st stage is open 1st stage should run...

  7. #7
    Join Date
    Nov 2006
    Location
    Southeastern Pa
    Posts
    19,506
    Quote Originally Posted by DNMechanical View Post
    I'm working on a Trane YCD240 RTU. this unit had been turned off for very long time 3+ yrs. Now customer need it. here is the problem
    Unit got correct power going to it, turned it on. It will not do anything, nothing run. LED light on the control board lit up. Shorted Test1 + Test2 for test mode, but it will not do anything... Checked voltage across test1 and TEst2 got 1.9 VDC. (it should be around 5 vdc). Checked wiring, all seem ok...I'm guessing control board is bad... what do you think? need help..
    I have never seen a good UCP that would not go into test mode.

    If I were there, I'd play with it, but without being able to do that, I'd lean toward a board.

    When you jumper test 1 and 2, does the red LED start to blink?
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

    RSES CMS, HVAC Electrical Specialist

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  8. #8
    Join Date
    Apr 2012
    Location
    Paper Street Soap Company
    Posts
    2,304
    They're not that difficult to run checks on. Any reason why that board would be bad?

    Down time shouldn't kill them. They're not avocados.

    Test should at least give you a fan if nothing else.

    Checking to make sure it has pressure is a good idea. Also on the older boards there was a 24v board mounted fuse

    They are 3 amp slow blow and they do go out from time to time.

    Check the following link for information
    http://www.trane.com/download/equipm...s/rtds9798.pdf

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