<p>A controller for a vehicle pneumatic system loads a compressor responsive to engine power absorption by the engine and air storage facility air pressure readings up to a pressure limit. The controller is responds to power demand on the engine in excess of an engine speed related global maximum and air pressure readings down to a global minimum for unloading the compressor. The controller provides for loading and unloading the compressor to maintain storage facility pressure within an operating maximum and an operating minimum which lie between the global maximum and global minimum pressures. The controller responds to air pressure readings reaching or falling below the global minimum for loading the compressor and to air pressure readings reaching or exceeding the global maximum for unloading the compressor.</p>
