A motor capacitor, such as a start capacitor or run capacitor, is an electrical capacitor that boosts the current or reduce the power factor to an electric motor, such as air conditioners, water pumps, garage openers, or forced air heat furnaces. A round or oval dual run capacitor is used in some air conditioner compressor units to boost both the fan and compressor motors and reduce the power factor. - Motor Start capacitors: are commonly used in single-phase motors to boost the value of their starting torque. It is necessary that the start should take in a small fraction of time (seconds) with the input of a high reactive power.