If you enjoy your home's ceiling fans, because they circulate air around the rooms and enable you to reduce the cost of heating and cooling your home, it can be a real nuisance when they stop working. Most things that can go wrong with a fan can be fixed. The question you'll have to answer is, "is it worth it to me to invest in fixing this fan vs. simply buying a new one?"
Replacing Ceiling Fan Motors
There are three basic things that can fail on a ceiling fan: the blades, the capacitors and the motor. Of these, the blades are by far the easiest and cheapest to replace. Unfortunately, they're also the part that's least likely to fail.
Capacitors are also cheap and easy to replace, but they can be hard to find. However, if you think you might have a motor problem, it could really be a capacitor. If the fan runs slowly, despite the speed setting, or if the motor hums to indicate that it's working but the blades won't spin, the problem is probably with the capacitor.
It's easy to replace a capacitor. It's usually contained in a black box inside the fan's switch housing. If this box is damaged in any way, it's also a good indication the capacitor probably needs to be replaced. To replace it, just unhook the wires and install a new one. The most difficult thing about replacing the capacitor is finding a proper replacement. Capacitors are rated in "microfarads," so you'll have to find that value on the capacitor and install a replacement with the same rating. Unfortunately, if your fan has more than one speed, you may find that it has a capacitor with more than one microfarad rating, and therefore more than one wire. If that's the case, refer to the schematic on the side of the capacitor that tells which wires go where. Capacitors are the part most likely to fail, so it may pay to learn how to replace them rather than replacing the fan.
If the motor does turn out to actually be the problem, you can certainly replace it. Some motors simply plug in and out of the fan. If you're not lucky enough to have one of those, you'll have to wire the new motor into place, matching the colored wires. Be sure to shut off the power to that circuit at the breaker box before you begin. Then unscrew the fan housing and remove it to replace the motor.
However, a quick check of ceiling fan parts sites reveals that the cheapest motors are almost $50, and most of them run at least $100 or more. Given that the cost of a fan is frequently $70 to $80, and even the most of the more expensive ones aren't much more than $150, it might well be cost-effective to simply replace the fan itself rather than going to the trouble of replacing the motor. It's your call.