I have a ceiling fan which is working with very slow speed, even when the selector is set to the max (5 speed). What is the reason for that? Is the reason a damaged capacitor or any other reason?

I just removed the speed controller and connected to the direct power line. After that, the issue remains. I have basic electronic and electrical knowledge but I couldn't find the reason. I am guessing that the capacitor is bad. Please help.

  • My first guess would be: mechanical issues. Dust in any of the moving parts or grease is no longer existing or conterminated with dust. Can the fan be easily moved manually when not connected to power? Did the speed decrease slowly over the years or suddenly? – MrSmith42 Jul 7 '16 at 10:56
  • The fan can be easily moved manually when not connected to power and speed is decreased slowly over the years not suddenly. @MrSmith42 – Chaminda Bandara Jul 7 '16 at 11:19

Does your fan have sealed bearings or ball bearings ? They can get dirty and cause mechanical drag. there may be other rotational loses coming into play. try a dry lubricant from a bike store if there are parts that need it. there could be a issue with the rotor or stator effecting the flux transfer to allow the motor to spin

What happens if the fan motor is plugged into the wall? does it run full speed? if it does there may be a fault in the electronics of the controller board

hope the idea help

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  • Thanks @Creative I didn't check about bearings and I will check and let you know. When fan is plugged into the wall still same issue. I tried without speed controller also. I am guessing about capacitor I want to confirm whether it is or not ? – Chaminda Bandara Jul 7 '16 at 11:25
  • I would think the bearings drying out or dust would be more of a problem with a ceiling fan. I would use penetrating oil on the bearings and allow it to work into the bearings. the grease in bearings is hydrocarbon based and when it drys out it gets very thick penetrating oil may provide several more years of life, then when it slows again add a bit more for a few more years. + – Ed Beal Jul 7 '16 at 13:16

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