What are pressure readings? Even good shops don't replace valve core stems. Why not? Because the hoses connected. I've been burned on a few systems where valve cores leaked after disconnecting hoses. Even if they didn't show signs of leaks. It's the weakest point on a A/C stem. Remove the caps. Check for oil slight pressure swish when the cap is removed. It it worked, I would suspect a leak somewhere.

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