Hi, new here from central VT. I own a 2004 GMC Sierra SLE extended cab with the 5.3L. I like to do what work I can myself, and I was a Mechanic in the Army from 02'-05'. Anyhow, just introducing myself. Figure this will be a helpful resource for my DIY projects and general advice if I run into problems. My AC just died the other day. I don't know much about how AC works, so here I am. I've owned my truck since last may of last year, and got it with 92k miles on it. It now has 100k.