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  1. #1

    scroll compressor

    I wanna verify if my train of thought is right or get slapped w a no lol

    I went to a service call complaint of a noisy outdoor unit. It was a trane heat pump w a scroll compressor. We checked the amps on it and it was running at 13 out of 18 amps w 40 degree outdoor temp. We thought it was high and that it could be a bad compressor. But when we attached our hoses we found the system was flat out of refrigerant.

    Normally I was under the impression that overcharged = high amps, low charge = low amps.

    But in this case, is it cus the system had no refrigerant and that the scroll compressor is suction cooled and that by not cooling the compressor it gave us a high amp reading?

  2. #2
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    you were pumping air most likely
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  4. #4
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    Quote Originally Posted by jpsmith1cm View Post
    You would have seen pressures if you were pumping air.

    How low do you want the amperage to go?
    if its flat out of refrigerant you can bet your butt it's pumping air
    “If I have seen further than others, it is by standing upon the shoulders of giants.” ~ Sir Isaac Newton


    I'm learning all the time, the tombstone will be my diploma!!!


    Did you ever stop to think, and forget to start again?

  5. #5
    Quote Originally Posted by jpsmith1cm View Post

    How low do you want the amperage to go?
    I would have expected somewhere at or below
    50% of the dataplate so somewhere around 8-9 amps.

    But am I right to think that the compressor not being cooled, due to practically zero refrigerant, causes "high" amps?

  6. #6
    Or is it just the compressor pumping air that led to a 13/18 amp reading?

  7. #7
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    Quote Originally Posted by coronachris0711 View Post
    I would have expected somewhere at or below
    50% of the dataplate so somewhere around 8-9 amps.

    But am I right to think that the compressor not being cooled, due to practically zero refrigerant, causes "high" amps?
    i would expect about 50% as well

    i dont think the lack of cooling would drive the amps up as much as you had

    there may be a bunch of moisture in the air your pumping that is contributing to the amp draw, and/or you could have a low megohm reading that would contribute to the high amps as well

    checked your gauges lately?

    did you megohm the compressor?
    “If I have seen further than others, it is by standing upon the shoulders of giants.” ~ Sir Isaac Newton


    I'm learning all the time, the tombstone will be my diploma!!!


    Did you ever stop to think, and forget to start again?

  8. #8
    Quote Originally Posted by Tommy1010 View Post
    i would expect about 50% as well

    i dont think the lack of cooling would drive the amps up as much as you had

    there may be a bunch of moisture in the air your pumping that is contributing to the amp draw, and/or you could have a low megohm reading that would contribute to the high amps as well

    checked your gauges lately?

    did you megohm the compressor?
    Ok awesome. It def did have moisture because a leak point was evident. And Yup we did check our gauges.

    But no, we didn't megohm. I don't know what that is

  9. #9
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    “If I have seen further than others, it is by standing upon the shoulders of giants.” ~ Sir Isaac Newton


    I'm learning all the time, the tombstone will be my diploma!!!


    Did you ever stop to think, and forget to start again?

  10. #10
    Awesome, so this tool checks for a "partial short" to a deeper level? I appreciate ur help and the link (it has good info, just printed it out to keep!)

  11. #11
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    Quote Originally Posted by coronachris0711 View Post
    Awesome, so this tool checks for a "partial short" to a deeper level? I appreciate ur help and the link (it has good info, just printed it out to keep!)
    don't know if they covered this in the link but;

    a megohm reading is will indicate the condition of the winding insulation

    and/or it will indicate if the systen is acidic

    after a megohm reading, if the reading is low, it must be determined whether the "low meg" condition is due to winding degredation or just acid

    acid can be cleaned up, degraded winding insulation is permanent damage that can not be fixxed

    some techs "think" megohming is just for trending, it's not just for trending/tracking winding condition!
    “If I have seen further than others, it is by standing upon the shoulders of giants.” ~ Sir Isaac Newton


    I'm learning all the time, the tombstone will be my diploma!!!


    Did you ever stop to think, and forget to start again?

  12. #12
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    How long has it been running flat? I would be concerned with where and how big the leak is before worrying about amp draw. Compressor probably has already been damaged.

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