Do any of you know what type of electric motor is used in ceiling fans?  We had to replace one recently because it was spinning very slowly and seemed to have little torque.  I hate to just throw it away but there's no schematic or repair manual and no info inside the fan, either. They only cost $50 - $100 but that's not really the point.

I did a DC resistance check on the rotor and stator wiring.  One was 90 ohms, the other was 75 ohms.

If it is cap start and has a bad capacitor,...

Could I just remove the little speed control electronics package and connect it to the AC directly?  I might only get one speed but I'm okay with that.  I could just try this but thought I'd ask before giving it the smoke test.

The lack of documentation is likely to result in this being thrown away.  

I have no what type of motor, but if you buy new, I highly recommend Casablanca fans.  My wife selected one seven years ago for a vaulted ceiling, which it had to rent twenty feet of scaffolding.  It recently died.  They have a lifetime warranty and I called.   Not only did they honor the warranty sight unseen, they let us "build your own" picking a fan, light kit and new blades, and color we wanted in the same size.  They then contacted a local electrician who called us about installing it, at no cost to us.  Putting in a fan is easy, but getting scaffolding in, which I don't own, not so easy.   They stand behind their product surprisingly!  

Good luck on the project.

Well, I tore the fan housing apart and found a small electrical module.  After removal, I found a circuit schematic for what's inside the package.  Using the diagram, the switches, an ohmmeter and the wiring, I created an electrical schematic for the fan motor and circuitry.  It's a fairly simple circuit.  

The parts (capacitors and resistors) are potted inside that shiny black potting compound and are not easy to get to.  Then again, I know they are toast!

Part of the package is swollen.  Another side is molten and has stress cracks.  The inner most edge is swollen, shows evidence of melting and has two protrusions where molten metal has erupted from inside.  The metal cooled and is now two blobs of metal protruding from the case.  I think we were very close to having an electrical fire.  I think the capacitors inside are fried, what do you think?

A replacement module is available but it costs $28 just for the replacement module.  A replacement fan is only $50.

I connected the rotor and stator wiring directly to the AC power.  I ran it without the 4 uF capacitor that is inside that module and is normally in the series with one of the windings.  The fan motor started and ran, and ran strongly.  After about a minute, I stopped it.  

I may hook it up like that.  A one speed fan is better than nothing.

Why would they put capacitors in series with the rotor and stator of an electric motor?  Is it for power factor control/adjustment?  It seems the fan has very little output power (very low output torque).  Is this because, absent the capacitors, the power factor is too low to move much air?

Furthermore, it seems the fan speed was adjusted by changing the capacitance in one half of the motor (rotor or stator).  One had a fixed 4 uF capacitor (and 75 ohms DC resistance).  The other had a variable capacitance in the circuit - 0, 5 or 10 uF.  

The 5 uF capacitors have a 330 ohm resistor in parallel with them.  The 4  uF has none.  


If I had an oscilloscope, I'd just measure (see) what was going on.  Unfortunately, I do not.