How do you add freon to a 96 Ford Taurus ac system?

You need gauges to properly add freon to the system. Using a kit from the auto parts store R-134a can be added to the low pressure hose, it will have a cap on it with an L stamped in it. Follow the directions on the kit. Take it to a repair facility. It will never work properly if you don't have it evacuated, checked for leaks then recharged. To add freon (real term is Refrigerant) to a 96 Taurus you need to access the Low Pressure port located on the firewall at the passenger side in the engine compartment. Go to your local autoparts store and buy a Refrigerant Dispensing unit and 1-2 cans of R-134a Refrigerant Also buy a can of Red Refrigerant Die. This will allow you to locate leaks in the system. Some also work as a sealant sealing the leaks temporarily. Ask your local autoparts store for assistance. They may even help you in their parking lot. (such as autozone or pep boys)