If your Cavalier's AC system needs refrigerant, you cannot legally use R-12. Instead, you'll need to have it converted to a compatible R-134a system, which requires a conversion kit and proper evacuation and charging. Using a substitute refrigerant without proper conversion can damage the system.
Do not attempt to recharge the system with R-12 or any other refrigerant without professional help from a qualified technician. They can properly diagnose the system, perform any necessary repairs, and convert it to R-134a.
