Most people don't pay too much attention to their ceiling fans—fans just dutifully circulate air around the room to help keep you cool and to stop the room from feeling stuffy. When one stops working, however, you definitely notice.
If a ceiling fan's light still works but the fan blades won't spin, it may seem like an electrical mystery. Unfortunately, it's a fairly common problem—different wires run to the light and the fan motor. Additionally, the motor relies on a capacitor which can fail due to a power surge in your home. Thankfully, the problem is usually easy to fix as long as you're comfortable with stripping and splicing wires. If your ceiling fan's lights are still working but the fan won't spin, read on to find out how you can fix it.
Check for Loose Connections
Loose connections are a common problem in ceiling fans, especially if they begin to wobble due to dust building up on the fan blades. The constant vibration can pull wires from their connections, preventing power from reaching the fan motor.
First, you'll need to turn off the power to your ceiling fan at your electrical panel. Remove the ceiling fan from its mounting bracket, and have a friend hold it up for you so it doesn't fall to the ground. Inspect all of the wires that run from the ceiling box to the junction box in the fan housing. If any wires have pulled loose from the boxes or have come free from their wire nuts, reconnect them or join them back together in their wire nuts. Reconnecting loose wires should restore power to your fan's motor.
Replace the Capacitor
If you don't notice any loose connections, then the problem most likely lies in the ceiling fan's capacitor. Ceiling fans are fairly simple machines with an in-line capacitor, and power surges to the ceiling fan can cause the capacitor to fail.
Open up the junction box within the ceiling fan's housing and look for a small black box. This is the ceiling fan's capacitor. In most cases, capacitor failure is immediately visible—the box will appear to be bulging. If this is the case, you'll need to replace it.
Write down the numbers on the front of the capacitor. You'll need to replace it with one that has the same number of wires and is rated for the exact same voltage and capacitance. You should also measure the physical dimensions of the capacitor to make sure that your replacement capacitor is the same size or smaller—this ensures that the new one will fit inside your fan's junction box.
You'll most likely have to order a new capacitor online. They can be difficult to find in stores. If you have an older ceiling fan, you may also want to try looking for a replacement on online auction sites.
Once the replacement has arrived, turn the power off to your ceiling fan at your electrical panel, remove it from its mounting bracket and then open up its junction box again. The easiest way to replace the capacitor is to simply overlay the replacement onto the old one and splice wires one at a time. Snip wires from your old capacitor about an inch away from it, strip a quarter inch of the sheathing off, and then use a wire nut to splice the wire to your new capacitor. Splicing the wires one at a time makes it easy to figure out which wire from the fan's junction box corresponds to where it attaches to the capacitor.
Once all of the wires are spliced, return the capacitor to the fan's junction box and mount the fan back onto the ceiling.
If replacing the capacitor doesn't work, call an electrician that provides residential electrical services. The problem may reside within the light switch or between the switch and the ceiling box, and it's a good idea to let a licensed electrician handle more complicated electrical work. Service calls for a ceiling fan are inexpensive, and you'll either be able to fix your fan or know definitively that the motor has failed and the entire fan requires replacement.