To test a system, have someone remove all the R134 safely. Next, replace the valve stem cores! A $2 part will ruin a system. It's the weakest point. Over time, the valve stem ports will leak. I've repaired so many systems by replacing the core stems. Most of them were quoted entire A/C system rebuilds. Only have a few did need rebuilding only because of compressor failure. Once all the R134 is out, put vacuum on the system. Vacuum from 45 min to 1:30 min. Close the hose valves and turn off the vacuum. Don't remove the vacuum/pump hose. It should hold vacuum down to 26 Hg. If vacuum goes above 24 Hg, I start looking for a leak. If it holds below 24 Hg for 30 min or more, I charge it up.

You can buy a cheap pump at Harbor Freight or Craigslist. Hoses are cheap too. Anyone can test the system. Replacing parts takes more skill and time. I learned from a seasoned mechanic. It's the one skill he taught me that has save me the most money.

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'06 X5 3.0i - bought @143,123 miles (12/26/20)