How do you add freon to a 1996 Audi A6 Quattro?

To add freon to a 1996 Audi A6 Quattro, first ensure the vehicle is turned off and the AC is set to the maximum cold setting. Locate the low-pressure service port, typically found on the larger diameter AC line, and attach the refrigerant can with a gauge. Start the engine and the AC, then slowly open the valve on the refrigerant can to allow freon to flow into the system, monitoring the pressure gauge to avoid overfilling. Once the desired pressure is reached, disconnect the can and check for leaks before closing the service port.