I'm trying to get my a/c working on my 2000 Cadillac Escalade. It's an early model so it's more akin to a '99. I learned early on to get parts for a '99 as the late '00 models are more like the '01. I was trained in servicing automotive a/c systems but that was nearly 50 years ago so I'm familiar with the basics but maybe not the details. I vacuumed the system before starting. I hot wired my safety switch so the compressor would engage. The label says it holds 40 ounces of refrigerant. I added 36 ounces plus maybe an ounce of UV dye to look for leaks if it doesn't hold. I'm getting 40 psi on the low side but nothing on the high side with proper gauge set. I suspect the valve on the high side charge port is bad and needs replaced. Input air temperature is 78 degrees and output is 52. So it's working. The compressor is filthy and looks like it's been leaking. If I have to open the system, I plan to replace the orifice tube, compressor and receiver/dryer. I noticed one connection with frost on one side and not on the other. I'm assuming this is where the orifice tube is on this model. Anything else I need to replace besides those parts and the hgh side charge port connector?