You cAnt sorry
They should never be mixed.
Freon R12
r12
R12
1993-95 for most.
Contains no (R12) Freon. Freon was banned in 1996.
R134a Freon is an oxymoron, Freon is R12 but the answer is yes, a subtle 'sweetish' odor
2 pounds of r134a. Not r12.
It came with R12 Freon. As R12 is cost prohibitive, have the unit converted to R134a refrigerant or a similar substitute.
None, the refrigerant is R134a not Freon which is R12.
There is only one Freon, and that is R12. R12 Freon came installed in your 1991 Chevy. It may or may not have been changed over to R134 Refrigerant. If not change it over, as the cost of R12 is unbelievably high an is no longer in production.