when ever I turn on my A/C it will vibrate pretty good and you can feel it in the cab of the truck. and it makes a low pitch humming noise.... I hope the pump aint going...... does anyone else have this problem?

 

sounds like a pump, usually if you add some compressor oil it will quiet down, pick up some at a napa or carquest in a can form usually made by johnsons or interdynamics, and then use a r134a can adapter with a shutoff valve and add about half can to see if it helps.

 

Maybe it's the pump...