Recharge A/C system?

Hello, if the tag on the front of the engine compartment calls for R12, then yes you have to use r12. Although there is a retrofit system to change over to r134a. Since r12 is so expensive not because they do not produce it anymore. I'll post some information on that.
On most retrofit kits come with only new fittings to accommodate the new r134a hoses, the system needs to be completely cleaned out of any old oil and I highly recommend replacing the accumulator (Receiver Dryer which is the canister type looking component that is inline on one of the ac lines). The accumulator is like a big filter and does hold some oil, but Chevrolet recommends replacing them too. I also recommend a compressor if you can find a retro kit that has one. The kit should come with new seals as well.

https://www.youtube.com/watch?v=B1VG1OHEfAM

https://www.youtube.com/watch?v=4EqdrBVb0sY