How could I determine if my AC compressor is running all the time? Once in a while when I am just sitting there I hear a click and the idle changes a little then it stops. When I am driving around if I put my hand next to the vent its colder than the air rushing by the truck. Seems to me like the AC compressor is running all the time. I know on my 95 I could push the AC button and listen to the idle change when the compressor cycled. The buttons and guages are off as far as AC goes, if its on its stuck on.