Ceiling fan capacitor help
Most ceiling fans use a type of motor known as a "permanent split capacitor motor". These motors have two coils, a "start" and a "run" winding. A capacitor is connected in series with the start winding to insert a phase shift, but once the motor is up to speed it becomes an auxiliary winding. In order to reverse the motor, the capacitor is applied to the "run" winding which then becomes the "start" winding. In some cases the windings may have taps to provide different speeds, in others the value of the start/run capacitor is lowered to provide lower speeds. Yet other designs will have additional capacitors wired in series with the motor as a whole to regulate speeds.
Signs of a bad capacitor in a ceiling fan include:
Fan runs slowly or not at all on all speeds
Fan will not start but will spin if started by hand
Certain speeds are slow or do not work
The motor hums and turns freely by hand but will not spin
The
capacitor is usually a black box inside the switch housing of the fan. If this
box appears burnt or melted in any way, that is also the sign of a bad capacitor
and it should be replaced.
Replacing a capacitor is easy, you simply
unhook the wires, and hook the new one in it's place. The only difficulty is
finding an appropriate replacement capacitor. Within a certain degree of
tolerance, the values of the replacement have to match the values of the
original capacitor. In fans with two wire capacitors this is easy, capacitors
are measured in "microfarads" (ex. 4uf) and you simply install a replacement 4
microfarad (4 uf) capacitor in it's place. However fans that use more than one
capacitor for speed regulation will often have a capacitor with more than one
value, and, therefore, more than two wires. For example, a three wire capacitor
(ex. 7uf+2.5uf) is simply two capacitors (a 7uf and a 2.5uf) sharing the same
casing and one common wire. For capacitors with more than 3 wires, usually there
is a schematic drawn on the side explaining the various values.
In any
case, you determine the number of wires and appropriate value(s) for the
capacitor. When obtaining a replacement, first check with the manufacturer as
they may have an exact match. Capacitors can also be purchased from ceiling fan
parts sites (for around $15 each), on eBay, and at hardware stores, home
centers, and other places that carry ceiling fans. If you can not find values
that match exactly, a difference of +/- one microfarad (1uf) or so should not
make a significant difference.
Lastly, older fans may use oil-filled
capacitors mounted inside the motor housing. These fan be replaced with newer,
smaller capacitors, but the larger metal capacitors are available from
electrical supply houses and motor shops. Contact ceilingfanrepair@yahoo.com for more
details.
Ceiling Fan Capacitors On Sale
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