How to diy ac recharge on a 1996 Audi A4 that doesn't have low pressure port

Get yourself a mastercool 82272 adapter at Napa (Napa Part NTE 783618 expensive at $19.99), autozone (Santech M0948 - $12.99), or your favorite parts place, they probably cost between 6 and 10 bucks .. Its a 1/2" ACME thread adapter but it fits onto the metric threads of the low pressure port just fine, and won't screw up the threads .. Disconnect the plug from the low-pressure switch, and install a jumper across the terminals .. Whatever you use for the jumper, I suggest that you put tape or some insulator over it so there are no accidental shorts. Unscrew the low pressure switch, it will puff out a little freon and compressor oil as you remove it but the fitting's schrader valve will prevent any more from coming out .. Next install the MasterCool adapter, which will not cause anything to leak. Next start the engine and set the AC for LO temp and maximum fan .. You should note that the compressor is spinning; nothing on the front of the pulley should be motionless .. Connect your R134a container to the MasterCool adapter and press the filler button .. You should feel the can get cold if refrigerant is being pulled out of it .. If you have a guage set you can use it to charge to the proper high and low pressure readings, then disconnect everything, take the adpater off and reinstall the low pressure switch .. Remove the jumper wire and plug the wiring harness back onto the switch and your done.