Extractor Fan start capacitor

  1. tona955 Member

    Messages:
    16
    Edinburgh
    Hi All,

    My small extractor fan motor is running slow and need a replacement capacitor. the existing capacitor was painted over so I cannot see its markings or value. I have tried a 25microF cap and it is still running slow.
    Is there any way to work out what cap size I need for this motor? I have attached a pic of the label on the motor, all I can see on the existing cap is HALE45 but this was a cap I took from my old faulty compressor and the extractor ran fine with it for over 4 years.

    Thanks in advance chaps
     
    • 20180327_173631.jpg
  2. carbon

    carbon Member

    Messages:
    758
    Location:
    S. Glos. U.K
    Not very clear on my phone but from the motor data plate looks like it should be a 25uf capacitor. If it’s still slow with a replacement possibly time for a replacement motor
     
  3. WorkshopChris Forum Supporter

    Messages:
    3,575
    Location:
    South East Essex
    Does the motor spin freely when rotated by hand, not a bearing getting tight.
     
  4. tona955 Member

    Messages:
    16
    Edinburgh
    Sorry, I meant to say i have already tried a new 25micro farid cap and it is still slow.

    The motor turns free when powered off, its not belt driven.
    Should I try a 45microF cap?
     
  5. Hog-Rider Member

    Messages:
    72
    Location:
    Henley in Arden in Warwickshire
    I'm probably wrong on this reply lol,I did not think that the Capacitor had thing to do with the speed of the motor ? I thought that the Capacitor was for the start up I.e. Taking the initial pressure off the Motor on start up.. Just a Thought.
     
  6. tona955 Member

    Messages:
    16
    Edinburgh
    Well yes, I can understand your thinking but this slow speed running happened before and changing the capacitor brought the fan up to normal speed, so i suppose it does effect speed.
     
  7. BarrieJ Member

    Messages:
    484
    Location:
    Milton Keynes, Bucks, United Kingdom
    Generally with fans, where not a great deal of torque is required to start, the capacitor is of a 'run' type, as opposed to a 'start capacitor'. If you check out the accompanying link, there might be some help there.
    https://www.achrnews.com/articles/84931-the-motor-doctor-diagnoses-motor-capacitors
    It's possible that your capacitor has shorted internally or if it's metal cased has grounded.
    Rather than explain here, there's no shortage of Internet advice on testing capacitors and the precautions required when doing so.
     
  8. tona955 Member

    Messages:
    16
    Edinburgh
    Yeah, I have tested the cap and it does not hold charge compared to a hood one.
    I just wanted to know if there was anyway of working out what size it ought to be in microFd.
     
  9. Seadog

    Seadog Forum Supporter

    Messages:
    2,478
    Location:
    NE London - UK
    To repeat what carbon said, it's 25μF @ 400V

    upload_2018-4-16_20-33-43.png
     
    carbon likes this.
  10. tona955 Member

    Messages:
    16
    Edinburgh
    Okay, I have tried that and the speed is still not the normal speed
     
  11. carbon

    carbon Member

    Messages:
    758
    Location:
    S. Glos. U.K
    Then it doesn’t look good for the motor. Can you see the windings inside the terminal box? Do some look darker than others? If they do then would have thought the motors been run to long with a failing capacitor and overhead the windings. One way to check is to remove one end cover and check the cord that holds the windings in place, if it’s broken and melted then motors got to hot and needs replacing
     
  12. tona955 Member

    Messages:
    16
    Edinburgh
    Good plan, they look good within the terminal block and I will check the windings later today.
    Thank you again for your support.
     
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