You add freon to the a/c by using the low side, suction side (larger hose).............
A 1999 Cavalier does not use Freon as a refrigerant.
R-134A, All Automotive parts stores have it in stock
R134a
Go to your local auto parts store. They will have kits with directions for you to do the job at home.
Freon was not installed in any vehicle built after 1995.Freon was not installed in any vehicle built after 1995.
Low pressure line - larger line from A/C compressor
Add it to the low presser side. It will be located on the evaporator on the fire wall on the passenger side of vehicle.
Low pressure line Larger line running from compressor
Buy a kit at Wal-Mart or auto parts comes with instructions
134
R134a
A135