When a ceiling fan won't turn, the problem could be mechanical or electrical. An example of an easy-to-fix mechanical problem is the failure to remove the packing tabs from your new fan, but unfortunately, most mechanical problems aren't so simple. Electrical problems are a bit more difficult to diagnose, but they're easier to fix. The problem could boil down to a loose connection, tripped breaker or faulty switch. At worst, it may be a burned-out capacitor.
Diagnosing the Problem
Step 1: Check for Mechanical Issues
Turn off the power to the fan and try rotating the blades. If you have trouble turning them, the gears may be stripped or there may be something interfering with the operation of the motor. You usually can't investigate or repair mechanical problems without taking down the fan and disassembling it. If the fan is installed in a damp location and hasn't been used for a while, it may be rusted or water-damaged.
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Step 2: Check the Wall Switch
If your fan is powered by a switch with an adjustable speed control, the fault may be in the switch -- the potentiometer could be damaged, or there could be a bad connection. It's easy to tell if the switch is bad. Turn off the circuit breaker and disconnect the switch. Use a noncontact circuit tester to confirm that the power is off. Connect the hot wire from the fan directly to the hot wire from the panel and turn the breaker back on. If the fan starts, replace the switch.
Step 3: Check the Fan Connections
Turn off the circuit breaker, go in the attic, uncover the electrical box for the fan and remove the nut caps from the wires. Check the connections to make sure they are sound and you don't see any blackening, which is the sign of a loose connection. Unscrew and remove the fan canopy and make the same inspection.
Step 4: Check the Capacitor
Most ceiling fans have a start capacitor that provides the torque necessary to get the blades turning. Humming, accompanied by a failure of the blades to turn, is a classic symptom of a failed capacitor. To check, turn on the fan so that the humming sound is audible and try turning the blades manually. If they start turning after a good push, you need to replace the capacitor.
Replacing the Capacitor
The capacitor is located in the circuitry you uncover when you remove the canopy from the fan. Follow a simple procedure to replace it:
Turn off the power before doing this, and remove the canopy with a screwdriver.
Pull out the capacitor and take a picture of it with a digital camera. This helps you find an identical replacement and it gives you a record of the wiring in case you lose track.
Snip the wires connecting the old capacitor to the fan circuitry and remove the capacitor.
Connect the wires of the new capacitor in exactly the same configuration. Strip the ends of the wires with wire strippers, twist pairs of wires together and secure them with wire caps. Replace the fan canopy.