My 03 D/A A/C has been very poor whenever the temp gets above 85 deg. Above 90 it was downright uncomfortable. The past couple of weeks it has been above 100 in the heartland.I never put a temp probe on the vents but I would sweat and would have to run the A/C blower on high continuously. I took the truck to the dealer and suggested he check the TSB's for 03 on A/C. He claims that none were applicable, however, he did order a new part. After further questioning, he claimed that another truck owner had claimed the same problem and was adamant that it be fixed (friend of dealership owner). They tried everything to no avail. They then found that the "orifice tube" was sticking and replaced it on his truck w/success. It supposedly controls the amount of freon flow in the system. The service writer claims they informed GM and a TSB was to be issued soon. They replaced it on my truck and what a difference. I now love my truck again and can drive it in comfort with the blower on 1 or 2 after just a few minutes.