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  1. #27
    Join Date
    Nov 2006
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    Southeastern Pa
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    19,573
    Quote Originally Posted by Randy S. View Post
    Check the line voltage. If it's within spec, then find the voltage drop on the low voltage.
    Even in this age of high tech DMMs, a 28V test lamp can be a good friend on the low voltage side, especially dealing with triac or other semiconductor outputs on stuff. Sometimes the high impedance DMMs can lie to you, simply because they are so high impedance.
    So true. High impedance is the way to go on low current electronic circuits, but not always so good in our applications.
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

    RSES CMS, HVAC Electrical Specialist

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  2. #28
    Join Date
    Feb 2010
    Location
    Ontario Canada
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    1,341

    Hmm

    One of the contactor coils is bad. When the contactor tries to pull in it drops the voltage (or va ) in the control circuit. This drop "Hangs up" the other contactors and prevents them from pulling in. Search for the defective contactor, you will find it.

  3. #29
    Join Date
    Nov 2006
    Location
    Southeastern Pa
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    Quote Originally Posted by trouble time View Post
    One of the contactor coils is bad. When the contactor tries to pull in it drops the voltage (or va ) in the control circuit. This drop "Hangs up" the other contactors and prevents them from pulling in. Search for the defective contactor, you will find it.
    I think he has that covered:

    I did ohm out the contactor coils and they tested good.

    So my money is on the CLO activity.
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

    RSES CMS, HVAC Electrical Specialist

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  4. #30
    Join Date
    Jun 2006
    Location
    New Jersey
    Posts
    4,340
    I have a few techs condemn contactors on Carrier's, because they pushed them in and they held. But they always locked out again.

    The CLO's use a triac circuits. By pushing in the contactor, there will be enough current to hold them in.

  5. #31
    Join Date
    Apr 2010
    Posts
    21
    I'm a new member trying to help others, Anyway you have your control voltage mostly it is 24VAC. This how the CLO does the s'tats calls for cooling the contactor energized on terminal 3 also energize the CLO logic circuit, must see at least 1.5 amps or the module will lock out. If the sensing loop does not sense amperage its open the contact between 2 and 3 and close contact 2 and X locking out the unit until 24VAC reset. Most Carrier unit has this CLO to monitor one leg of the compressor circuit. good luck

  6. #32
    Join Date
    Feb 2001
    Posts
    368
    I see where flange asked in an earlier post if transformer was tapped right.
    Have not seen a response ,may have missed it.If so my apologies.
    I have seen units do this due to transformer primary not tapped to proper voltage.Usually 208 v unit and trans is tapped to 230v.Doesnt sound like much but it makes a difference when pulling all your low voltage loads at same time.Works sometimes but not always.Has enough voltage to hold your
    contactors in but sometimes not pull in last stage. Good luck.

  7. #33
    Join Date
    Nov 2004
    Location
    Auburn, AL, USA
    Posts
    597
    Timebuilder at post #16 got the the best possibility IMO. Several others have chimed in on the CLO controls. Pushing in the contactors and then having them stay engaged makes it seem like the control voltage is weak at the contactor or the contactor is bad. What happens is that the CLO is reset when the contactor is manually pushed in and full control voltage is then applied to the contactor.

    I thought the CLO should lock out if:
    Too low or no amps on the monitored leg after a predetermined length of time allowed for start-up.
    After start-up time, too low amps or too high amps on the monitored leg.

    If the monitored leg wire is switched to the wrong compressor wire, the CLO can seem like a real PITA.
    If a replacement compressor has a different amps from the factory original, the CLO often gets blamed.
    jt

  8. #34
    Join Date
    Mar 2010
    Location
    Morgan Hill Ca.
    Posts
    1,235
    Pull the common on the CLO and see if she fires off...The CLO needs the common to lock anything out....Common pulled it uses the safeties as a control circuit...So it could potentially short cycle itself to death...

    A Redneck temporary fix is to install a delay on break TDR on the Y1 and Y2 circuits and pull the common until you figure out WTFO...

    GT
    If a day goes by and you have learned nothing, I hope you got a lot of sleep.

  9. #35
    Join Date
    Jun 2006
    Location
    New Jersey
    Posts
    4,340
    Quote Originally Posted by jtrouse View Post
    Timebuilder at post #16 got the the best possibility IMO. Several others have chimed in on the CLO controls. Pushing in the contactors and then having them stay engaged makes it seem like the control voltage is weak at the contactor or the contactor is bad. What happens is that the CLO is reset when the contactor is manually pushed in and full control voltage is then applied to the contactor.

    I thought the CLO should lock out if:
    Too low or no amps on the monitored leg after a predetermined length of time allowed for start-up.
    After start-up time, too low amps or too high amps on the monitored leg.

    If the monitored leg wire is switched to the wrong compressor wire, the CLO can seem like a real PITA.
    If a replacement compressor has a different amps from the factory original, the CLO often gets blamed.
    But if you push in the contactor with the CLO locked out, the contactor will engage and remain engaged.

  10. #36
    Join Date
    Feb 2010
    Location
    Ontario Canada
    Posts
    1,341

    Hmm

    Quote Originally Posted by timebuilder View Post
    I think he has that covered:




    So my money is on the CLO activity.
    That may be, I have seen this before, same problem, it ended up being a contactor.

  11. #37
    Join Date
    Dec 2008
    Location
    caribbean
    Posts
    76
    have the tranformer been replaced? maybe the VA ARE TOO SMALL , LOOSE OR RUSTY CONECTION SOMEWHERE

  12. #38
    Join Date
    Nov 2004
    Location
    Auburn, AL, USA
    Posts
    597
    Quote Originally Posted by ascj View Post
    But if you push in the contactor with the CLO locked out, the contactor will engage and remain engaged.
    The CLO will restore full control voltage to the contactor when the contactor is manually pushed in. The CLO resets when it detects the correct amperage on the monitored wire.
    jt

  13. #39
    Join Date
    Jun 2004
    Location
    Clayton,NC
    Posts
    407
    Ive seen this happen before when the wrong size contactors are used. Check the amp rating of the contactors. If they are suppose to be 30 amp and someone installed three 50 amp contactors you will loose controll voltage at each contactor.

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