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  1. #1
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    Aug 2018
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    York YCAS Unloader voltage too high

    I have a York M#YCAS0200EC46XAASS
    S#RCHM8700AA that when the slide step is at 0, the voltage to the Unloader is at 14vdc.
    Other similar YCAS chillers go from 0-10vdc. 0 being unloaded. 10 being loaded. What would cause my Voltage to be high?

  2. #2
    Join Date
    Nov 2011
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    I worked on one last week that used 30vdc. For the load solenoid.

    What kind of problem are you having.

  3. #3
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    Aug 2018
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    Thread Starter
    Mine is also measures 30vdc while the solenoid is disconnected . The coil is magnetized even when the circuit switch is off. Is that normal?

  4. #4
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    maybe, some of them modulated current to the solenoid.

    what is the problem you are experiencing?

  5. #5
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    Aug 2018
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    Thread Starter
    I have read about modulating current but I have another YCAS that modulates a 0-10vdc signal that is proportional to the 0-75 step slide valve command. I cant find how to check this in the book. If anyone knows, I'm going back tomorrow to work on it.

  6. #6
    Join Date
    Dec 2014
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    New Mexico
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    Does it do it to just the one compressor or all in this chiller.
    The signal comes from the I/O board.
    The I/O boards takes a 12 VAC from T3 and modulates out 0-10 VDC. Could be that signal is stuck “closed”. Is it causing the compressor to load?
    T3 transformer is a 240 primary/ 24 secondary. Has 120 to it to make the 12VAC.


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  7. #7
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    Aug 2018
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    Thread Starter
    Are you saying that on the i/o exp board j3 connection should be 12vac? The book was indicating that is should be 24v. That might also explain why my discharge and oil temp sensors went bad, they also plug into This board. This is a new account for my company and I'm finding a lot of strange stuff.

  8. #8
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    Dec 2014
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    New Mexico
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    There should be a sticker by T3 explaining the reason for the 240 primary on that transformer.


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  9. #9
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    Aug 2018
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    Thread Starter
    Thanks Chev, the sticker was gone and there was a 120 - 24 v transformer feeding the i/o board power. I changed out the transformer but the board is bad now due to being fed 24vac. Even with the circuit switches off I have 13vdc to the solinoids. Thanks for your help. Nowhere on the print or in the book does it say anything about that transformer being a 240-24 with 120 on the primary. In fact, the book says 120 primary with 24 secondary. Thanks for your help buddy. Problem solved. Writing up the board.

  10. #10
    Join Date
    Aug 2018
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    Post How I read what year my York AC was made?

    Model: H4DE0245066A

    Serial: ENHM888030

  11. #11
    Join Date
    Dec 2014
    Location
    New Mexico
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    Get the board and only the power plugs. Plug in the others in just in case there is a transducer or thermistor acting up. Keep the load/unload coils unplugged until you have got it running and it all looks good shut down and try one at a time. Just in case.

    Took you down the wrong path about the 240/120 transformer. That mess was to power up the old school BAS interface boards. Truck on!


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  12. #12
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    Aug 2018
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    Are you able to let me know how to read this: H4DE024506A. What year was this built?

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