Capacitors are used to help start motors. They work on a very simple principal. Hitting a rod at an off angle will cause the rod to spin. If you held a rod in your hand and wanted to get that rod to spin, you would not hit the rod straight on. You would want to hit the rod on an angle, to soften the blow to your hands and transfer more of the force to spin off of the rod. This is exactly what a capacitor does to the motor's shaft to help it spin with the torque that is was designed to run at. The capacitors are rated in micor farud's, which are a measurment of the amount of torque that they will produce. There are two major types of capacitors; a run capacitor and a start capacitor. The run capacitor is usally in a silver metal tin can filled with a oil substance. These are the most common type in home HVAC equipment. The other type is a start capacitor, which is usually identified because it is in a black plactic can.
 |  |
| run capacitors | start capacitors |
