ceiling fan runs, but slowly

Discussion in 'Electrical Forum discussion & Blog' started by aviation76, Oct 26, 2008.

  1. aviation76

    aviation76 New Member


    Where to begin. I moved into a new house three years ago. The master bedroom has a ceiling fan installed. I decided to replace the toggle single pole AC switches with dimmer switches (slide types). The wall plate has two switches, one to power the light and the other to power the ceiling fan. I replaced both toggle switches with dimmer switches.

    If my memory serves me correctly, the speed of the ceiling fan was fine. I guess over time the speed degraded. It ran at a setting somewhere between low to medium. Yes, the pull chain on the fan is set to high.

    So I decided to switch out the fan with another ceiling fan in our house that has worked fine.

    I switch out the fans and now the fan in our master bedroom spins on HIGH without any problems. A few hours later I notice the speed has decreased dramatically.

    Note that the when I reinstalled the original ceiling fan in the other room the high speed setting did not return.

    Now I am left scratching my head. What is causing the fan to run at a lower speed even though I set it to high?

    The only though I have is that I may have damaged the capacitor. Did the dimmer switch I install cause this? Or someother wiring problem? I have another ceiling fan in the house that utilizes a three-speed ceiling fan switch and that works fine (as opposed to the slide-style dimmer switch).

    If I install a different style switch will the speed settings be back to normal?

    Your comments and advice are greatly appreciated.

    Thank you.
  2. jwelectric

    jwelectric Electrical Contractor/Instructor

    North Carolina
    More than likely
  3. hj

    hj Moderator & Master Plumber Staff Member

    Cave Creek, Arizona

    You need a speed control switch, not a dimmer switch. Hopefully you have damaged the dimmer switches and not the fan motors.
  4. aviation76

    aviation76 New Member

    Thanks for your prompt replies.

    I will replace the switch with a new speed control switch.

    I hope this will solve the "low speed issue". If not, looks like I will be replacing the capacitor.

    I will keep everyone posted...
  5. jwelectric

    jwelectric Electrical Contractor/Instructor

    North Carolina
    Don't you mean the motor
  6. aviation76

    aviation76 New Member

  7. Alectrician

    Alectrician DIY Senior Member

    To test it simply remove the dimmer and wire nut the two leads together. This will send a full 120V to the fan and you can test the operation.

    Don't use a variable fan speed control. They tend to make the fan hum. Use a 3 or 4 speed fan control
  8. aviation76

    aviation76 New Member

    Well, after some thought I decided to purchase a new fan (a much needed decor update was in order) instead of repairing the fan. I am considering giving the fan to my parents to install in one of their bedrooms.

    Out of curiousity I disassembled the fan just to poke my nose around. I located the speed control capacitor. It looked fine and did not indicate any signs damage (i.e. melting, bulging, etc). When there are not any physical signs of damage, can the capacitor still have internal damage?

    I also removed and replaced the dimmer switch with a rotary 3-speed fan speed control. When I removed the old switch, I noticed that I did indeed originally install a switch intended to be used to control fan speed (Lutron Skylark Slide-to-Off Fan Control, model SFSQ-F). I mistakenly stated that I was under the impression that I installed a dimmer switch. Anyway, I installed the rotary switch when I installed the new fan and everything works great. Could the original switch mafunctioned causing harm to the fan? And if so, is the motor or the capacitor damaged?

    Just FYI, I have a lot of experience installing ceiling fans so I can attest that all wiring at the fan and switch are correct.

    I did not have time to test the original fan. My parents only have a single pole toggle switches in their rooms. I kind of wonder if the fans will operate normally after going through the "adventure" at my house.

    Your expertise is greatly appreciated.

  9. Thatguy

    Thatguy Homeowner

    I don't think the cap controls speed; it is a start/run cap.

    You can check it with a 1 megohm resistor, a 9v battery and a DMM.
    Put the cap in parallel with the items above.
    Read your voltage (between 9v and 9.6v for a new battery).
    Disconnect only the battery.
    When the voltage reaches 37% of initial value, the number of seconds it took to get there is the capacitance in uF.

    So, 9v starting, goes to 3.3v in 22 seconds is 22uF.
    You don't even need to wear face protection when doing this test.
  10. jar546

    jar546 In the Trades

    Speed capacitor?

    Don't you mean the FLUX Capacitor? :)

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