Clutch : The clutch connects a moving part on the car such as the ac pulley mechanical fan or engine to what needs to be moving like the ac compressor, fan or transmission. There are several types of clutches. Some clutches contain a friction material like a manual transmission clutch. Other clutches may have a hydraulic fluid or an electro magnet. Automatic transmissions even contain multiple clutches. The clutch on a vehicle is the opposite of the brake.