Recharging AC coolant question

I have a 1991 Olds Cutles Ciera and the ac needs recharging with coolant. How do I know what kind to use? I was told if it was changed to the new 134a there would be a sticker under the hood saying so. But I find no sticker anywhere. Is there any way to tell for sure whant kind mine takes? I have both kinds as well as the hoses to put it in with I just dont know which to use in this particular car.

Should be on a yellow sticker. Mine is on drivers side under the hood, on the round bump where the shock/strut goes up into lol. Sorry I don't know what to call it. Or near where the hood latch is.

I did a search on autozone.com with your model car/year and shows R134A.

I'm sure someone here can verify this to be sure though.

An easy way to tell if its R12 (freon) or R134a is the service ports. I THINK your low side service port is on the accumulator/drier. High side is usually in-line somewhere (maybe near the condenser)...take the plastic cap off the connecter (if they put it back on, and regardless of which refrigerant both caps will unscrew), if the outside of the port has a screw on connecter (like an oversized tire valve stem) it should be R12. If it has a quick connecter (like an oversized air tool fitting) it should be R134a. BUT someone still could have mixed refrigerants....the ports are only a guide to what should be in there...

R134a didn't become common in these cars until 1994. Sites like Autozone list R134a for ALL cars seeing that if you don't have R134a already, they want you to switch too it.

Look at the refilling ports and see if they look like tire fittings. If they DO, then look for a refrigerant called FREEZE12. It is a R12 replacement that is not hazardous to the environment, and is cheaper than real R12. It also works a LOT better than the R134a conversion.