Hi all. I have an 05 suburban z71 w/ the 5.3 (non-flex). Last year it ran out of a/c so I took it in and had it recharged. They were supposed to use the UV dye. It again ran out of a/c so I got a refill kit with the uv light to see if I could find the leak...couldn't see anything. Either they didn't use uv dye or my leak is somewhere mysterious. Anyway, I went to charge it today with a UV charge, but now the compressor won't turn on. I put half a can in like the instructions said but still wouldn't. Are there any low pressure switches that turn the compressor off to protect it when it runs out of 134? How can I go about getting it kicked on to test? Hopefully the compressors do not have a history of going bad. Thanks!!