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Thread: Motor just hums... won't start

  1. Back To Top    #1

    Join Date
    May 2015
    West Palm Beach

    Motor just hums... won't start

    I have a US Motors 1081 Pool Motor with the specs below. The pump started to hum without turning over. Did some research and changed out the capacitor a No Name 189-227 MFD Round with a Dayton 189-227 MFD Round 110-125VAC. Pump started up without incident. A few weeks later, pump started to hum again and would not turn over. Thought the new capacitor went bad so changed it out with a new same spec Dayton from Grainger. No luck. Have had to "jump start" the pool pump with my drill which starts the pump just fine and it keeps running for the entire timer cycle. However, it will not start by itself. I can turn the shaft by hand as well as the impeller. It just seems that the capacitor does not have enough juice to kick the motor over. Can I increase the voltage of the capacitor to the 220VAC version or will this not work? Is there another troubleshooting item I should try before taking the motor into the shop? I have read about rapping the motor with a hammer, but have not deployed this technique yet. I am trying to work from simple solution to more complex, with the most complex and expensive being to replace the pump motor. The pump is approximately 2 years old at this point. Any help or other troubleshooting tips would be most appreciated. Should additional information be need, kindly contact me. Thank you.
    15x30 Free Form Pool
    US Motors 1081 1.0 HP Model C55CXKMB-5012 RPM 3450 VOLTS 230/115 POOL PUMP MOTOR
    In Ground
    Hayward 90 Sq. Ft. Filter

  2. Back To Top    #2
    Mod Squad JohnT's Avatar
    Join Date
    Apr 2007
    SW Indiana

    Re: Motor just hums... won't start

    Welcome to TFP!

    The capacitor voltage is just how much voltage can be applied without damaging it. No effect on function.

    The start cap just provides a phase shift so the motor will move. The other thing that helps the motor get started is the centrifugal switch on the back. This is a mechanical switch that closes when the motor is stopped, but has a weight to open the switch once the motor starts spinning. Shut the power off and look under the back cap of the motor for the switch and see if it moves freely.
    TFP Moderator
    20K Gallon 20X36 Vinyl Inground
    Hayward S244T Sand Filter with 1HP Whisperflo Pump. Liquidator C-201 and Solar Heat

  3. Back To Top    #3
    rmal75's Avatar
    Join Date
    Aug 2017
    Allendale, NJ

    Re: Motor just hums... won't start

    I'm having the exact same problem with the exact same US Motors model. I'm wondering, did you ever diagnose the issue and how did you fix it?


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