GM Genuine Parts Engine Cooling Fan Clutches are designed, engineered, and tested to rigorous standards, and are backed by General Motors. These engine cooling fan clutches control the speed of the radiator fan based on the temperature of the air after it passes through the radiator fins. GM Genuine Parts are the true OE parts installed during the production of or validated by General Motors for GM vehicles. Some GM Genuine Parts may have formerly appeared as ACDelco GM Original Equipment (OE).