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  1. #1
    Join Date
    Feb 2012
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    Toronto Canada
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    York 410A RTU Causing callback's

    So I have a customer who has a york RTU that is only 3 yaers old 410A. I got a call middle of July No cooling Found the compressor not compressing. Got new compressor under warranty pulled charge changed compressor with proper procedure.(flowed nitro etc) The unit ran fine for 3 weeks get a call not cooling again. Go out thier find it tripped on high head preasure. I jumper out the HPS and the RTU climbed to 800PSI and the obstruction cleared. I stayed and cycled the unit and took readings and everything is A1. So today I go by to do maintence and I find the unit tripped on High preasure again. I do the same thing and it clears and unit is running fine. I have pulled every panel off the unit I can not see an obstruction in the system. It is not a TXV its just a metering device that you canot pull apart. None of the lines are frosting. It all looks ok.

    So what do you techs think? Something is causing an obstruction when the units off?
    To much oil in the system causing High preasures?
    What do my Fellow Techs think?

  2. #2
    Join Date
    Jul 2009
    Location
    Columbia, MD
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    3,990
    is the coil dirty? see if there is a service bulletin on the unit. is it the microchannel? you may need a delay on start for the pressure switch.

  3. #3
    Join Date
    Feb 2012
    Location
    Toronto Canada
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    Quote Originally Posted by gravity View Post
    is the coil dirty? see if there is a service bulletin on the unit. is it the microchannel? you may need a delay on start for the pressure switch.
    The coil was cleaned twice this season. It is a microchannel What makes you say I need this Delay on the Preasure switch? Is this a call back from York for some of thier new 410 microchanel RTU?
    Have you had simialar problems?

  4. #4
    Join Date
    May 2004
    Location
    Salt Lake City/Tooele
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    2,489
    There was a point in the middle of production of many of the York RTU line that they switched over to the micro-channel coils from the tube/finned coils. In error the factory was charging the micro-channel with the same weight charge of R410a as the tube/finned systems. This very slight over charge...I mean 10 ounces or so, will cause major nuisance high pressure issues, only upon compressor start up. It will not happen all the time, but when it does it will spike upwards of 600 to 900 psi and then burp right back to normal.
    York is VERY VERY quiet about this issue, but it is common knowledge, thanks to this site.

    So your unit may have been involved with the factory over-charge. If not, still keep in mind that it only takes a few ounces of over-charge in a packaged unit with micro-channel technology using R410a, to see head pressure spikes upon compressor start up.

    As for the delay on the high pressure switch, I was advised by York that this WAS NOT the proper solution. They know this is going on in the industry, but they are correct in stating that it is prematurely killing the compressors. They recommend remove entire charge and slowly recharge system while it is operating to a 6 degree subcool and leave it at that. IGNORE the factory charge on the placard.

    I know all of this since we had 23 SunLine units we installed on a new strip mall a few years back and all hell broke loose. York did right with us by having their local field rep come out and verify the issues and a warranty claim was submitted for each unit to cover our labor.

  5. #5
    Join Date
    Jul 2009
    Location
    Columbia, MD
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    yes. a slight overcharge will also cause this.

  6. #6
    Join Date
    Aug 2012
    Location
    west burbs,il
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    145
    I've also noticed that the scrolls seem to have a built in by-pass valve internally (hissing noise), I've questioned a couple techs and they're not quite sure about it. I was working on a split by goodman (junks) r410, it was over charged slightly causing extreme high head psi but low side stayed idle at 225, thought the compressor plates got screwed. However recovered charged, vacuumed and recharged fresh. Perfectly fine. Not sure if u guys ran into this problem but I thought I'd throw it out there, so watch out for it.

  7. #7
    Join Date
    Jul 2009
    Location
    Columbia, MD
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    3,990
    yes you are correct. there is a internal relief that opens and bypasses. also newer scrolls have a temperature device in them that will disable it from pumping. some may condemn the compressor before cooling it down and checking it.

  8. #8
    Join Date
    Aug 2012
    Location
    west burbs,il
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    145
    Hmm. That's interesting. I thought I heard about it before but thought I was goin nuts when everyone looked at me cross eyed when I explained that issue. Thanks

  9. #9
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    Feb 2012
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    Toronto Canada
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    Thanks guys overcharged from factory was the cause. York said recover 8 oz of gas which I did all is good now Thanks

  10. #10
    Join Date
    May 2010
    Location
    Canada
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    833
    Is there anyway to tell by MN or SN which units are affected by the factory overcharge?

  11. #11
    Join Date
    Aug 2012
    Location
    west burbs,il
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    145
    wish i had an answer for that, that would be helpful

  12. #12
    Join Date
    Aug 2012
    Location
    MA
    Posts
    39
    What is your suction pressure? I would check your condenser coil and also remember 410a is very picky and requires a deep vacuum.. Is your high side fluttering at all?

  13. #13
    Join Date
    May 2004
    Location
    Salt Lake City/Tooele
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    2,489
    Quote Originally Posted by eddiegoodfellar View Post
    Is there anyway to tell by MN or SN which units are affected by the factory overcharge?
    Mostly York "ZF" series RTU's from late 2009 to half way into 2010.
    Coleman units also affected were the D*YZ, D*PZ, D*YQ, and NL series for the same period.
    Last edited by slctech; 08-22-2012 at 10:12 PM.

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