Results 1 to 8 of 8

Thread: Motor Run Capacitors

  1. #1
    Join Date
    Jul 2007
    Location
    Virginia
    Posts
    13,303
    Post Likes

    Confused Motor Run Capacitors

    The general rule is that once a capacitor get 10% below it's rated Uf value, it needs to be replaced. I've seen capacitors that aren't leaking or bloated, and are 25% below their rated value, and they still seem to be working fine; or are they working as they should? My question is: once a compressor or evaporator fan capacitor loses more than 10% of it rated UF output, is the fan motor running at a slower rpm? What is really happening to the motor when the capacitor isn't at it's full rated capacity?

  2. #2
    Join Date
    Jul 2001
    Location
    Delaware
    Posts
    1,232
    Post Likes

    Chances are

    the motor is going to be drawing high amps if the cap is weak.
    Work is for people who don't know how to fish.

  3. #3
    Join Date
    Sep 2007
    Location
    Raleigh, NC
    Posts
    31
    Post Likes
    Grady White is right. The cap helps the motor develop torque. If the cap is going bad, then the motor will draw more current to get the required torque.
    The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge
    ...It is better to be a little smarter than you have to be, instead of a little dumber than you should be!

  4. #4
    Join Date
    Apr 2007
    Location
    MN
    Posts
    297
    Post Likes
    Agreed, caps are cheap, replace it.
    S**t or get off the pot!

  5. #5
    Join Date
    Jul 2007
    Location
    Virginia
    Posts
    13,303
    Post Likes
    Thread Starter
    Thanks for the info

  6. #6
    Join Date
    Sep 2007
    Location
    Maryville Tennessee
    Posts
    92
    Post Likes
    I was once told in a class that capacitors have a 100% failure rating.

  7. #7
    Join Date
    Sep 2007
    Posts
    20
    Post Likes
    Quote Originally Posted by rundawg View Post
    The general rule is that once a capacitor get 10% below it's rated Uf value, it needs to be replaced. I've seen capacitors that aren't leaking or bloated, and are 25% below their rated value, and they still seem to be working fine; or are they working as they should? My question is: once a compressor or evaporator fan capacitor loses more than 10% of it rated UF output, is the fan motor running at a slower rpm? What is really happening to the motor when the capacitor isn't at it's full rated capacity?
    i thought it was +or- 6% ofits ratting

  8. #8
    Join Date
    Apr 2007
    Location
    MN
    Posts
    297
    Post Likes
    Quote Originally Posted by LBDavis View Post
    i thought it was +or- 6% ofits ratting
    I've always gone by +/- 10%
    S**t or get off the pot!

Posting Permissions

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