Abstract: A system for controlling air flow to an engine cooling system includes a control computer responsive to a number of engine and/or engine accessory operating conditions, and to various engine operational states to control operation of an engine cooling device. The engine operational states are each a function of at least engine fueling commands and include a "free energy" state corresponding to zero fueling, an "absorbing additional torque" state corresponding to zero fueling and activation of either service brakes or engine brakes, and a "needs additional torque" state corresponding to a rapid positive change in fueling, recent gear shifting to the lower gears of the transmission with fueling above a predefined level or a high rate of change in fueling rate. All other engine operational states are defined as a don't care state.

Abstract: A system and method for air compressor control wherein the air compressor is loaded only when engine activities require it to be loaded or when free engine power is available to operate the compressor. An air compressor system is an engine-driven, piston-type compressor which operates in a loaded and an unloaded mode and provides air to a vehicle's air powered devices, such as service brakes, air suspension, windshield wipers, etc. The operating mode of the compressor is controlled by a pressure activated air governor which applies an air signal when pressure in a reservoir reaches a set level that activates a cap valve on an unloader stopping the air compressor. When the air pressure in the reservoir drops below a lower set pressure or when energy is "free," such as during downhill operations, the air governor exhausts the air signal allowing the air compressor to resume operation.

Abstract: An electronic air compressor control system and method including an actuator connected to an air compressor for regulating the loading and unloading of the air compressor based on predetermined conditions, a power supply electrically connected to the actuator for supplying a voltage thereto and a plurality of switches electrically coupled to the actuator and power supply for controlling the supply of voltage from the power supply to the actuator in order to control the operation of the air compressor based on a predetermined air compressor exhaust temperature threshold and minimum and maximum pressure thresholds. The unloading and loading of the air compressor is based on a predetermined air compressor exhaust temperature when the pressure within the wet tank is between the minimum pressure threshold and the maximum pressure threshold.