A 1990 Buick Century with a V6 engine most likely used
R-12 (Freon-12) refrigerant in its air conditioning system. However, it's crucial to
not assume this. R-12 is no longer manufactured due to its ozone-depleting properties. Any R-12 that remains is likely reclaimed or recycled. The system may have been retrofitted with a different refrigerant (like R-134a) at some point.
To know for certain what refrigerant is currently in the system, you need to have a qualified technician perform an AC system check. They will have the proper equipment to identify the refrigerant.
