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  1. #1
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    Confused TRANE YDC090 issue..Help/info Please.

    Hi,

    I have a TRANE YDC090C3LABE (S# P37100846D) that I'm not able to get the heat, or AC, to operate. The blower comes on and runs continuously, but can't for the life of me narrow down the problem.

    I had a faulty limit, near the inducer, that I replaced and the one in the blower compartment is ok. The unit does have a new ICM board. If I put the unit into test mode I get the heat and cool to work. If I jump the relay on the UCP that energizes the control transformer the inducer starts and the heating sequence begins and runs. Why would cause this relay not to be getting energized? I spent over an hour tracing and checking wires in the unit....I feel like I've been defeated and I don't like to give up. I still be on that roof if I didn't have another job I had to go to.

    BTW, I have a solid red led on the UCP and the economizer opens to the minimum set angle. I don't know of the economizer could be causing an issues?...

    I haven't worked on many of these TRANE YDC units. This is a older model. I can hardly read the wiring diagram on it and have no manuals to work with. This unit also runs off a conventional thermostat and has a interface board if that's what it's called.

    ANY and all info someone who has more experience with this model RTU would be greatly appreciated.

    Thanks for your helps.

  2. #2
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    It's not ems controlled is it?

    sent using crapatalk

  3. #3
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    If test mode works then it's not the rtu according to trane. Tstat? Wiring? Plug? Economizer holding out cooling? With a seperate heat issue?

  4. #4
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    Quote Originally Posted by Nytefog View Post

    I have a TRANE YDC090C3LABE (S# P37100846D) that I'm not able to get the heat, or AC, to operate.

    I can hardly read the wiring diagram on it and have no manuals to work with.
    I emailed you the Service Facts.
    Instead of learning the tricks of the trade, learn the trade.

  5. #5
    Join Date
    Nov 2006
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    One favor to ask:

    When you have an issue like this, please post it in the Pro section, so Rundawg can post the service facts there, and we can have a deeper conversation about the issue, along with a follow-up.

    You can ask the mods to move this thread to the Pro Commercial forum area by clicking on the black triangle in the lower left hand corner of your first post, and type your message asking the thread to be moved in the text box, and then click send.
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    2 Tim 3:16-17

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  6. #6
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    Thread Starter
    Quote Originally Posted by icy78 View Post
    If test mode works then it's not the rtu according to trane. Tstat? Wiring? Plug? Economizer holding out cooling? With a seperate heat issue?
    I checked all the Tstats wires and it's not calling for anything. I jumped out heating and cooling but nothing happens.

    Is their a way to disconnect the economizer? I thought it was suppose to cycle completely open and close before anything would start? It just opens to its minimum opening position and stays their.

  7. #7
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    Thread Starter
    Quote Originally Posted by rundawg View Post
    I emailed you the Service Facts.

    Thank you. Hopefully I can figure out what's going on. It's just confusing how everything works in test mode.

  8. #8
    Join Date
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    Let me ask you this...

    is there anything connected to two screws on the terminal strip, at the bottom, which are labeled EMERG STOP?

    And if not, is there a copper strip firmly connecting the two screw heads together?
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    2 Tim 3:16-17

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  9. #9
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    Yup, only two things will stop that contactor from pulling in. E-stop or open safety. (Assuming wiring and components are good)

  10. #10
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    Quote Originally Posted by Nytefog View Post
    I checked all the Tstats wires and it's not calling for anything. I jumped out heating and cooling but nothing happens.
    If it does NOT have the additional board that allows use of a regular stat, jumping heat and cool(R to Y or R to W) will do nothing. Even with that board, not sure it will do anything if jumped.

    Only way to verify operation is by test mode. That confirms all functions work. It also IGNORES all safeties(if I remember correctly). Thus, if it won't run with a stat call, you most likely have a safety issue.
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  11. #11
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    Test will not run if E Stop is open.

    CTI board is only used on the large UCP controller. The smaller RTRM controller can be jumped out like any other unit.
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    2 Tim 3:16-17

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  12. #12
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    Thread Starter
    I know their isn't a emergency stop label on the terminal strip. I'll have to look when I go over again.

    I got the YDC090 running. It had something to do with the economizer. I was checking connections and I'm not sure what I did but the heat fired up and stayed working as I turned the unit off and on multiple times.

    I really need to disable the economizer because the previous outfit working on the system sealed the intake off with sheet metal and barometric relief damper.

    These two ydc090 are a nightmare and the crane needed to replace the units cost more than the system replacement it's self.

    Thanks for all the input I greatly appreciate it everyone!

  13. #13
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    Quote Originally Posted by pacnw View Post
    If it does NOT have the additional board that allows use of a regular stat, jumping heat and cool(R to Y or R to W) will do nothing. Even with that board, not sure it will do anything if jumped.

    Only way to verify operation is by test mode. That confirms all functions work. It also IGNORES all safeties(if I remember correctly). Thus, if it won't run with a stat call, you most likely have a safety issue.
    In test mode the safetys still have priority.

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