The ceiling fan capacitor is an important part of the electric circuit that starts the fan motor and lets it rotate at more than one speed. If the capacitor has failed, the fan will not start or it will spin slowly. Because ceiling fans have simple circuits with few parts, you can identify and replace the capacitor without having extensive technical knowledge. The most important factor in a successful repair is to get the right replacement capacitor and wire it the same way as the old one.
Prepare to Open the Fan Casing
Make sure you have the necessary tools, including a voltage tester, a screwdriver that matches the screws on the fan, wire nuts, wire cutters and wire strippers. Switch off the power to the room that contains the fan by opening the breakers at the electrical panel or removing the corresponding fuses. Place a stepladder under the fan and make sure it is high enough for you to reach the fan without having to stand on the top two steps.
Find the Capacitor
Unscrew the screws on the lower part of the fan casing and pull off the cover. You may have to remove the light fixture first if a light is attached to the fan. Before working on any of the wiring, check each wire with a voltage tester to make sure it is not live. A non-contact voltage tester is especially safe because it lets you check for voltage without verifying each wire. The capacitor is a small box-shaped unit with one or more wires leading to the speed switch and the on-off switch. Cut the capacitor wires close to the capacitor and remove it from the fan casing.
Buy the Replacement Capacitor
Get a replacement capacitor for your particular ceiling fan. Find a replacement capacitor that has the same number printed on it as the original capacitor, if possible. A different model of capacitor will work as long as the number of wires is the same and the technical specs are the same as those printed on the old capacitor. The capacitance in microfarad, or uF, and the voltage rating in volts have to be identical. If the voltage is too low or the number of wires is different, you may damage the new capacitor. If the capacitance is not the same, the fan many turn slowly or not at all.
Install the New Capacitor
Strip about a half-inch of insulation from the ends of each wire on the new capacitor and from the cut wires in the fan casing. Twist together the ends of the wires with the same insulation color in a clockwise direction and screw a wire nut onto each twisted end. Place the new capacitor inside the fan casing and reinstall the cover. Switch on the power and test the fan at each speed to make sure it is working properly.