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  1. #1
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    Winding resistances jumping

    Hey itís ya favorite HVAC noob here.

    So I got a single phase scroll compressor from the job today. (Itís scrap, we replaced with a new one)

    Instead of throwing it away I brought it home because Iím curious. So when I set the multimeter to ohms and touch any two combinations from common, start, or run the numbers jump. I thought I wasnít getting a good connection so I attached alligator clips from my leads to the terminals and the same thing. Any insight?


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  2. #2
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    Yes they do Jump under certain conditions. Scrape the pine or clean with emery cloth. Alligator clips wiggled give a better reading with a standard OHM meter.

    Get a Mega Ohm and play with that on old units.

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  4. #3
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    Question, is the ohms only jumping at first and then go to OL? Constantly jump? How about from terminals to casing of compressor?

  5. #4
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    Thread Starter
    Quote Originally Posted by Bruce Melton View Post
    Question, is the ohms only jumping at first and then go to OL? Constantly jump? How about from terminals to casing of compressor?
    It jumps normally from some high number to a lower number. I understand thatís because of the inrush of voltage the meter sends out. So after it settles from that it goes to another number and continues to drop and then back up to a different number.

    It never goes to OL. It constantly jumps, yes. From terminals to casing is OL. (I scratched away through the paint to make sure Iím on the metal of the casing)


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  6. #5
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    Thread Starter
    Quote Originally Posted by pecmsg View Post
    Yes they do Jump under certain conditions. Scrape the pine or clean with emery cloth. Alligator clips wiggled give a better reading with a standard OHM meter.

    Get a Mega Ohm and play with that on old units.
    Any recommendations on a megger?


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  7. #6
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    Quote Originally Posted by Sabr7 View Post
    Any recommendations on a megger?


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    How much Money do you have?

  8. #7
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    Quote Originally Posted by Bruce Melton View Post
    Question, is the ohms only jumping at first and then go to OL? Constantly jump? How about from terminals to casing of compressor?
    Too ground should be ZERO always!

  9. #8
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    A little read on Motors:
    Attached Images Attached Images

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  11. #9
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    Thread Starter
    Quote Originally Posted by pecmsg View Post
    How much Money do you have?
    $300-500. Sounds like youíre gonna say a fluke..


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  12. #10
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    Quote Originally Posted by pecmsg View Post
    Too ground should be ZERO always!

    Well let me try this again..


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  13. #11
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    Quote Originally Posted by Sabr7 View Post

    Well let me try this again..


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    Don't worry about megging until you begin to get to compressors or motors that cost 3-5k or more. Not worth it. Basic ohm is all you need.

  14. #12
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    I'll test with my Fluke...………….If they want more I'll call an independent and take a % of there bill to confirm!

  15. #13
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    Quote Originally Posted by Sabr7 View Post
    Hey it’s ya favorite HVAC noob here.

    So I got a single phase scroll compressor from the job today. (It’s scrap, we replaced with a new one)

    Instead of throwing it away I brought it home because I’m curious. So when I set the multimeter to ohms and touch any two combinations from common, start, or run the numbers jump. I thought I wasn’t getting a good connection so I attached alligator clips from my leads to the terminals and the same thing. Any insight?


    Sent from my iPhone using Tapatalk
    when you cranked up the new compressor was there any issues ? or did the replacing go smooth

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