displacement an electronic control valve 42 controls the angular position of the swash plate 36 to establish the length of stroke of the pistons 38 and therefore the displacement the compressor may be controlled by pneumatic controller instead of an electronic controller the system includes a controller 44 for disengaging the compressor 12 in response to an engine being in initial operation and air conditioning on signal and for a predetermined length of time in other words the controller 44 sequences the compressor 12 in response to the engine being in initial operation for a predetermined number of engine minutes and in response to an air conditioning on signal to reduce the output of the compressor 12 for a predetermined number of seconds and to increase the output of the compressor 12 for a predetermined number of air conditioning minutes the controller 44 includes a timer 46 for establishing the predetermined number of engine and air conditioning minutes as five and the predetermined number of seconds as ten for air conditioning off or reduced output and the predetermined number of air conditioning minutes as two and for providing a second predetermined number of seconds as ten following the two minutes of air conditioning this illustrated in fig4 and 5 in.