Page 1 of 3 123 LastLast
Results 1 to 13 of 28
  1. #1
    Join Date
    Sep 2011
    Posts
    85
    Post Likes

    Low head, normal suction, HIGH amps

    5 ton scroll compressor in a split system.

    Suction ~40psig
    Discharge ~210psig
    Amps 30+A
    Superheat ~17

    It is a 3 phase compressor, pulls 30 amps from the get go and will go all the way to 40 amps (and shut off)

    The winding(s) resistance is about .5 ohms on all of them. It also doesnt sound great when it is running. I recovered 20 pounds of refrigerant from this system, recharged with around 7.5 pounds... After cleaning the ridiculously dirty evaporator.

    Just looking for affirmation, thank you for your input.

  2. #2
    Join Date
    Jan 2004
    Location
    PA
    Posts
    70,423
    Post Likes
    7.5 pounds sounds low on a 5 ton split system.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  3. #3
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    26,437
    Post Likes
    Quote Originally Posted by wdshea View Post
    5 ton scroll compressor in a split system.

    Suction ~40psig
    Discharge ~210psig
    Amps 30+A
    Superheat ~17

    It is a 3 phase compressor, pulls 30 amps from the get go and will go all the way to 40 amps (and shut off)

    The winding(s) resistance is about .5 ohms on all of them. It also doesnt sound great when it is running. I recovered 20 pounds of refrigerant from this system, recharged with around 7.5 pounds... After cleaning the ridiculously dirty evaporator.

    Just looking for affirmation, thank you for your input.
    Did you measure amps on all 3 legs?

  4. #4
    Join Date
    Apr 2007
    Location
    T.C minnesota
    Posts
    12
    Post Likes
    I'm guessing R-22. If so looks like low suction, normal head. more info would help. I like to megaohm the compressor to ensure the windings are good.

  5. #5
    Join Date
    Oct 2001
    Posts
    6,966
    Post Likes
    split unit what was the ambient around the condenser 210PSI air cooled is low for R-22.how is the condenser on being clean...flush it inside out.... is this a commercial site strip mall or residence?
    "when in doubt...jump it out" http://www.youtube.com/watch?v=U1qEZHhJubY

  6. #6
    Join Date
    Sep 2011
    Posts
    85
    Post Likes
    Im sorry, i was thinking of my suction saturation when i said 40, pressure was around 69psig on the suction. Yes i checked all three legs. I cleaned the condenser twice. This is commercial.

    Megaohm the windings to ground?

  7. #7
    Join Date
    Apr 2012
    Location
    Paper Street Soap Company
    Posts
    2,304
    Post Likes
    You can use a megger if you have one. Isolate the leads from the compressor and megg from the compressor terminals to ground.

  8. #8
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    26,437
    Post Likes
    typically, a short to ground is not going to cause high running amperage.

    That would be more likely to cause high instantaneous amperage and result in a breaker trip.

    I would leave the megger in the truck here.

    I'd look for a performance curve on that pump and see what the manufacturer says that it SHOULD draw under those conditions.

    I suspect that you'll be replacing a compressor, soon, though.

  9. #9
    Join Date
    Sep 2011
    Posts
    85
    Post Likes
    The olp trips pretty quick, it never pulls less than 30 amps, so it only runs about 5 minutes, if that. I thought that maybe a previous tech may have the motor running backwards, so i switched some leads. AmP draw went to 12A but the compressor sounded like hell, so i'm certain it was running the right way.

  10. #10
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    26,437
    Post Likes
    Quote Originally Posted by wdshea View Post
    The olp trips pretty quick, it never pulls less than 30 amps, so it only runs about 5 minutes, if that. I thought that maybe a previous tech may have the motor running backwards, so i switched some leads. AmP draw went to 12A but the compressor sounded like hell, so i'm certain it was running the right way.
    A grounded winding will typically pop the breaker/overload instantly, not over a couple of minutes.

  11. #11
    Join Date
    Sep 2011
    Posts
    85
    Post Likes
    What else could this be? I was thinking shorted windings

  12. #12
    Join Date
    Jul 2012
    Location
    central VA
    Posts
    217
    Post Likes
    What is the LRA and what is the compressor rated at? 30 plus amps sounds high in a 5 ton system.
    I rather do nothing and be happy than to do something and not be happy

  13. #13
    Join Date
    Dec 2002
    Location
    Arizona
    Posts
    4,451
    Post Likes
    My guess would be the bearing are going bye bye. 30 amps on a 5 ton 3 phase compressor? Not long for this world!
    Make your expertise uniquely valuable.

    Make your influence uniquely far-reaching.

Page 1 of 3 123 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

Related Forums

Plumbing Talks | Contractor MagazineThe place where Electrical professionals meet.
Quality Home Comfort Awards