Be advised that R134A is not a drop in substitute for Freon12. If the AC was converted to R134A you are a go. Look for the R134 conversion sticker and quick connect type couplings on the service fittings.Best thing just happened, walked into farm and home and r124a is 5$ a can.
Got home and my mustang is already converted, a can later and she blows cold!!
The typical sticker looks like this, yours may be different
Typical low pressure side R134 coupling
Typical high pressure side R134 coupling