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  1. #1
    Join Date
    Jun 2012
    Location
    Batonrouge
    Posts
    19

    carrier rtu on walgreens contactor issues

    I have ran into few carrier units where the contractors are not sucking in all the way. I changed the transformer and a few months later I'm here again facing the issue. Voltage is 208 and I do not have a voltage drop on my primary or secondary. A couple other techs are finding the same problem with their Carrier units. These are on Walgreen, any help would be great.

  2. #2
    Join Date
    Apr 2012
    Location
    Paper Street Soap Company
    Posts
    2,304
    Wire to conventional stats or a EMS system ?

    You can isolate the stats and just operate it from the control panel to see if its in the ubit or in the stat wiring.

  3. #3
    Join Date
    Jun 2012
    Location
    Batonrouge
    Posts
    19
    Ems system. It only happens every once in a while if I reset the unit it will run fine for about a month or two.

  4. #4
    Join Date
    Jan 2008
    Location
    Dallas ,Texas
    Posts
    3,723
    Wow with the Carrier model number you didn't provide the possibilities are endless.
    UA 100

    It takes three people to do anything around here. Two do the work, one explains to the crowd of people who showed up when they seen smoke and flames.

  5. #5
    Join Date
    Sep 2007
    Location
    NH
    Posts
    1,159
    If you push the contractor in does it stay running?????

    If so the unit may have been locked out. Pushing the contactor in will reset it or turning the unit off and on will reset it.

    Model number would help.

  6. #6
    Join Date
    Apr 2004
    Location
    Maryland
    Posts
    522
    What is your control voltage at the contactor when it is not pulling in? I have seen Carrier units locked out through the CLO board and have 16-17 volts at the contactor. When you push it in the contactor stays. 17 volts is not enough to pull in the contactor but when you push it in it will hold it closed.

    I would be checking your safeties closely. Maybe you have a condenser motor overheating or an intermittent blower.

  7. #7
    Join Date
    Jul 2011
    Location
    Lehigh Valley, PA
    Posts
    464
    You have a dirty low voltage connection somewhere. Low voltage will show 24v when tested with your vom but once put to a load will drop and create issues you state.

  8. #8
    Join Date
    Apr 2012
    Location
    Paper Street Soap Company
    Posts
    2,304
    Its has something to do with the EMS inputs.

    All the Carrier package RTUs Ive worked on and the only time Ive had anything remotely simar was when they were wired through a NOVAR system.

  9. #9
    Join Date
    Feb 2006
    Location
    USA
    Posts
    4,381
    What is the voltage & tolerance of the ems controllers? All inputs should be isolated in a perfect world. One chain of accounts i do the ems folks don't want more than 24 for control & they prefer 22. This utilizes system xfmrs & has been causing issues as of late. Especially in L serious lennox stuff which recognizes the higher input for safeties being closed & such. Lately I've been adding step down xfmrs off the units xfmr secondary just keeping their controllers at the lower scale. What a fkn pain in the a$$ on a carrier with no room in the control compartment as it is

  10. #10
    Join Date
    Apr 2007
    Location
    Pa
    Posts
    758
    Standard units up to 15 tons or so, our expierence, it is always the time delay

  11. #11
    Join Date
    Feb 2006
    Location
    USA
    Posts
    4,381
    Quote Originally Posted by HvAckid82 View Post
    Standard units up to 15 tons or so, our expierence, it is always the time delay
    For me with carriers I've been finding economizer problems causing most of my control issues when units are tapped right on the xfmr

  12. #12
    Join Date
    Jun 2012
    Location
    Batonrouge
    Posts
    19
    If I push the contactor in it will hold it in. If I shut the unit off and kick it back on it works fine. Last time this happened I changed the transformer from 40 va to 75. It worked fine for about a month. I know im going to have to go back. I checked the voltage at the transformer and I had 25 volts. Sorry no model num fellas. I'll get it next time.

  13. #13
    Join Date
    May 2004
    Location
    SE Pennsylvania
    Posts
    957
    Quote Originally Posted by snowbird225 View Post
    If I push the contactor in it will hold it in. If I shut the unit off and kick it back on it works fine. Last time this happened I changed the transformer from 40 va to 75. It worked fine for about a month. I know im going to have to go back. I checked the voltage at the transformer and I had 25 volts. Sorry no model num fellas. I'll get it next time.
    If you have a a CLO the unit is probably locked out like others said and when you push the contactor in you basically reset it, same as cycling power. There is an output on the CLO that will have power when it is locked out, I forget what terminal it is. What was the voltage at the coil before pushing the contactor in and after?

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