Although it's hard to imagine now, it won't be long until the dog days of summer have us cranking up the air conditioner every time we get in the car. Keep Your Cool , a free publication from the Environmental Protection Agency, answers that question Until recently, all auto air conditioners used CFC-12 as a refrigerant. But because it damages the protective layer of stratospheric ozone, which shields us from overexposure to ultraviolet radiation, production ended at the close of 1995. Alternative refrigerants not harmful to the ozone are now being used in new vehicles, but if your car is designed to use CFC-12, don't worry.
Continued use is perfectly legal and enough has been produced to meet demand in the years to come.
Conversion during a major overhaul may not involve much additional cost, and will make replacing refrigerant easier in the future. Otherwise, continue using CFC-12 until it becomes unavailable.