[Brian in Tucson]

There's nothing magical about the a/c system on your boxster. Take it to a proper shop that has the correct equipment, have it diagnosed and fixed, and refilled by weight. Compared to replacing a compressor, a/c shops are very reasonable.

It's okay to get a reading on system pressure. There's a sensor that won't let the compressor run if the refrigerant is low. But only do that as a screening diagnostic. There's a reason that HVAC guys are certified and licensed.

Also, we've been sold a bill of goods that R134a isn't bad for the environment. It is, and it's illegal to vent it to the air. All forms of freon should be removed correctly, so that they can be reused. R134a is gonna be banned soon.