A fan assembly (10) which incorporates variable pitched blades (152), is driven by the engine of a vehicle and is used in cooling the engine. A control system (248) is provided which is responsive to at least one signal representative of an operating parameter of the engine and a second signal indicative of a desired cooling requirement to establish an efficient pitch for the blades of the fan assembly. In one embodiment, the speed of the engine is sensed and used in combination with a cooling requirement signal developed by the engine control module (205) to regulate the pitch of the fan assembly. In a second embodiment, engine charge air temperature and coolant temperature signals are utilized in establishing the desired pitch. Furthermore, fuzzy logic controls (290) can be utilized to anticipate the cooling needs of the engine based on variations in the overall dynamic system as derived from information available through the engine control module.