noisey ac compressor and no ac working

i have a 2001 dodge ram 1500 5.2 engine,The ac is not working right not much cold air coming out,i notice the compessor in the cab is notically louder when it cuts in and seem to cut in two much i counted off 9 times in one minute it ran even with the air on low!somebody told me that it is the ac low pressure switch,can i change that myself or does it have to serviced by dealership??thank...