My ac would only get down to 78 degrees out of the vents on a hot day so i installed a valve in the heater hose last summer that brought it down to about 50 degrees it worked great until it got hot this summer.So i started digging around on the forums,found out that gm f**ked up and now they offer some updated parts but i was to tight to spend the cash.I finally bought a new dryer and a ajustable orfice.replaced the parts and added 3ozs of oil,pulled a vaccumn recharged system with 24ozs of freon.Now it will freeze your ass off with 38 degree air.I just wanted to let everyone know that should fix the problems on these trucks.