I have a 99 Burb that I bought 6 months ago. I just got around to checking out why the AC didn't work. It had an obvious leak where the hose connects to the compressor. I cleaned up the outside, replaced the seals (washer w/rubber), pulled a vacuum on the system and it held (YESSS!). I charged up the system and it cools pretty good in all the front vents. However, the rear vents feel like ambient air temperature. My first guess was that perhaps the expansion valve for the rear evaporator core was stuck and won't open. Does anybody have any experience with this happening? Also, the AC compressor never cuts off. I have been cycling it off every few minutes via the "AC" button on the dash to keep things from freezing up. Any ideas on that? Thanks!