welded contactor - Page 2
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  1. #14
    Join Date
    Nov 2006
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    Southeastern Pa
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    17,708
    I would recommend that "sitting on the bucket" process.

    If the windings are good and there are no shorts to ground, the idea that this is being caused by the compressor is possible, but not great.

    Most likely, the reference to chattering (an intermittent condition in the control circuit that causes the contactor to pull in a drop out rapidly) is the real cause.

    Most of the time, I find a defective pressure switch/ loose wire nut/terminal connection/worn thermostat micro relay that causes chattering.

    I have never replaced a compressor yet for this condition that checked out properly with the meter.
    [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. #15
    Join Date
    Jul 2012
    Location
    Western KY
    Posts
    1,221
    I would start with control Circut as well. The TDOB and isolation relay ideas are both very good ideas. I would be looking for voltage drop on control circut. The TDOB should tell you for sure though. If it welds with it in then it's on the line side, comp. if it stops welding it get your stool out and start tracing that control Circut out. Ther time delay may treat the symptom but will not fix the problem. Good luck.

  3. #16
    Join Date
    May 2002
    Location
    evansville indiana
    Posts
    943
    Quote Originally Posted by Tommy knocker View Post
    I would start with control Circut as well. The TDOB and isolation relay ideas are both very good ideas. I would be looking for voltage drop on control circut. The TDOB should tell you for sure though. If it welds with it in then it's on the line side, comp. if it stops welding it get your stool out and start tracing that control Circut out. Ther time delay may treat the symptom but will not fix the problem. Good luck.
    I'm teliin troy you have a stool on your truck
    mikeacman

  4. #17
    Join Date
    Nov 2006
    Location
    Southeastern Pa
    Posts
    17,708
    Quote Originally Posted by Tommy knocker View Post
    I would start with control Circut as well. The TDOB and isolation relay ideas are both very good ideas. I would be looking for voltage drop on control circut. The TDOB should tell you for sure though. If it welds with it in then it's on the line side, comp. if it stops welding it get your stool out and start tracing that control Circut out. Ther time delay may treat the symptom but will not fix the problem. Good luck.

    Some delay on break modules will not react quickly enough to accomplish this purpose, when the chatter rate is high enough to retain sufficient voltage through the module to keep it turned on, yet not enough to hold the armature of the contactor in the energized position.
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

    RSES CMS, HVAC Electrical Specialist

    AOP Forum Rules:







  5. #18
    Join Date
    May 2002
    Location
    evansville indiana
    Posts
    943
    Quote Originally Posted by timebuilder View Post
    Some delay on break modules will not react quickly enough to accomplish this purpose, when the chatter rate is high enough to retain sufficient voltage through the module to keep it turned on, yet not enough to hold the armature of the contactor in the energized position.
    agreed...

    I would use a three wire....supposed to be less problematic in respect to the above issue
    mikeacman

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