Elect Motor Capacitors

Discussion in 'General Electronics Chat' started by Buddy51456, May 1, 2014.

  1. Buddy51456

    Thread Starter New Member

    May 1, 2014
    Hi, I picked up a Craftsman air compressor at a yard sale cheap knowing there was something wrong with it. I brought it home, plugged it in, it started and in about half a second blew a dedicated 30A time delay fuse. Still screw in fuses in my pole barn so that's getting annoying. I figured it was the start capacitor so I purchased a one with the same specs and installed it. The motor started for a split second and quickly blew again a dedicated 30A time delay fuse. I was going to replace the run capacitor but could not find one like it. I could find one with the same ratings but this one has two red wires and a brown coming from the top and sealed. Not knowing how it was wired I was hesitant on spending the money so I took the plastic off the side and found the two reds come from the top and the brown comes from the bottom of the capacitor. Although thinking more about it after replacing the start capacitor it should not blow the fuse, or should it? I would assume it would just struggle some. This is with no load on the pump as the air fittings are removed. Is it most likely shorted windings in the motor?
  2. MaxHeadRoom


    Jul 18, 2013
    May be at a yard sale for a reason? ;)
    If it attempts to turn over and start for a short period, it could be a winding shot.
    If it does not attempt to turn, take the belt/load off and give it a spin by hand when applying the power.
    If it still blows or it turns somewhat it could be either the centrifugal switch welded shut (not likely) or the windings.
    Maybe calls for a strip and examination!
  3. BillB3857

    Senior Member

    Feb 28, 2009
    Plug the model number of the compressor into the sears repair site and you should be able to get a manual on the unit. It may even include a wiring diagram and part list.