compressor playing up

  1. 123hotchef Member

    Messages:
    8,736
    Location:
    Kent
    My compressor has started playing up.

    It builds up to about 100psi then the motor starts struggling and just sits there trying to turn.

    Any ideas people. it is a 3hp belt driven compressor the oil is only a year old and it does not get much use anymore.
     
  2. Cobbler

    Cobbler Codger bodger

    Messages:
    4,639
    Location:
    Gloucestershire UK
    Motor burnt out, a coil gone so it doesn’t develop full power possibly?
     
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  3. WorkshopChris

    WorkshopChris Forum Supporter

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    What's the capacitor configuration?
    Cap Start. (1)
    or Cap Start & Cap Run. (2)
     
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  4. 123hotchef Member

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    Location:
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    surley if the motor was burnt out it would not get up to 100psi?

    Chris I am not sure let me check I think there is only one cap
     
  5. Cobbler

    Cobbler Codger bodger

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    Don’t know, just floating ideas about.
     
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  6. 123hotchef Member

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    Location:
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    Looks like the one cap does both does both is that right chris
     
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  7. WorkshopChris

    WorkshopChris Forum Supporter

    Messages:
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    Location:
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    Yes one cap, so a standard capacitor start motor, might be worth testing to confirm it's still within tolerance. But if the cap was faulty I would expect problems way before 100psi.
    Looks like you have a loose or high resistance connection to the thermal overload but wouldn't be the main problem.
    Does it feel ok when turning over by hand? any hot bearings on compressor or motor?
     
  8. sako243

    sako243 Member

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    Location:
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    If the cap was failing it would struggle to start. Given it's struggling when under load then there's extra resistance from somewhere - either mechanical or as suggested partially burnt out motor. Measure the ohms across the windings - should only be a couple at most, if they're higher then the winding is toast.
     
  9. brightspark

    brightspark Member

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    yarm
    the conector near that white block looks like its been overheating
     
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  10. 123hotchef Member

    Messages:
    8,736
    Location:
    Kent
    yes I thought that about the connector on the overload block it looks bit toasty!

    I will try turning it over by hand.

    I have had my two compressors hooked up together for ages now I disconected them to work on this fault and it worked ok today well just up to max pressure I do need to try using it though.
     
  11. Mine was was doing the same once and changing the oil cured it, is there a faulty non return valve between the pump and tank?
     
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  12. 123hotchef Member

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    8,736
    Location:
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    the NRV was new last year so I hope not
     
  13. angellonewolf

    angellonewolf Member

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    ^^^^ better that than a new motor :whistle:
     
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  14. 123hotchef Member

    Messages:
    8,736
    Location:
    Kent
    dam right the unloader was new too and that is working fine
     
  15. 123hotchef Member

    Messages:
    8,736
    Location:
    Kent
    this compressor is a bit hit and miss sometimes it makes it up to 150psi sometimes it falls short and starts playing up normally about the 110-120psi mark. the motor just stops and sits there trying to turn weird one
     
  16. MCKDAVID Member

    was this not the one where the cover was missing on the fan casing of the motor? going back a fair while now, did you ever replace it? if not it's maybe cooked the windings and they're breaking down at higher temperatures.
     
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  17. carbon

    carbon Member

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    Have you checked electrical connections outside of the compressor, plug and socket for example to check for poor connections or overheating
     
  18. 123hotchef Member

    Messages:
    8,736
    Location:
    Kent
    You my friend have great memory. It was a cracked cover the fan was still there I did fix the cover though. I need to check this melted connector on the cap. Plug is ok I unplug it when not in use
     
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  19. Turbo Member

    Messages:
    3,458
    Location:
    Fermanagh, Northern Ireland
    That could be part of your problem, the pressure switch is set too high! Adjust it back so that it switches the compressor off at 110-120psi, that will give the motor a much easier time. I can't think of any tools that need anything over 90psi to work!

    I would also suggest trying a new capacitor, yours could be failing & a new one is only £10.

    Also change the oil for a multigrade engine oil, maybe 15w40. In this colder weather standard monograde 30 compressor oil gets thick & a compressor will sometimes struggle to start.
     
  20. 123hotchef Member

    Messages:
    8,736
    Location:
    Kent
    I think it is adjustable it has always been set to 150psi. I shall have a look later. I thought the cap was only used for the starting up of the motor?
    The oil was new last year and the compressor has not had much use since I changed it, it was never a problem in the cold winter months earlier this year that is for sure.
     
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