Don't know if this will help you, but since the techs couldn't find my leak, I'm changing out my schrader valves, using this tool:
Amazon.com: Mastercool 58490 Universal Master Valve Core Kit: Automotive
My '03 uses three schrader valves that cost about $2 for all three. When I changed two of them today, one of my High Side valves was leaking for sure, I heard air release when I removed the cap and also saw
residual clear fluid in the valve, ( Freon or oil, I suppose ). I have one valve left to change out, but it appears to be buried under the passenger headlight, with the valve pointing downward through a hole
in the body. I'm going to get under my car tomorrow to see if I can access the last schrader valve. One of the schrader valves screws into a plastic fitting, (on the high side hose). Not surprised it
leaked.