2003 Chevy S-10 AC dash switch

Hello, My 2003 Chevy S-10 with the 4.3l v-6 engine has a problem with the AC control on the dash. This is the dial that controls the max ac, ac, and defrost selection depending on what you want to use. Mine seems to be stuck on the max ac spot, because when I move the dial to the other selections it doesn't change at all. Because I live in Florida I'm ok with max ac right now but eventually I will need the defrost. I can see the back of the dial through a slot in my dash right above it and it looks like it might just be an electrical switch of some sort that might just be malfunctioning. Are those replaceable, and is that a item that I can get at auto parts stores or is it a dealer item? Thank, Fritoguy15 :confused: