2000 chevy truck ac

2000 silverado, ac quit working--- heard a click while i was on the highway-- cool air turned to warm air. I attempted to add some 134 but apparently it was already up on pressure. The ac compressor does not engage at all, no change in engine rpm-no click. My brother has same truck and told me his switch went out, light still worked on it. He was told this is a common problem. Anyone heard of this? IF so anyone have any idea what that switch costs=-- and how difficult to take apart dash to replace?