There should be a sticker somewhere in the engine compartment. If
not, if you can find one of the fittings on the AC lines and look
at it. R12 fittings are threaded, the 134 are smooth with a single
groove running aroung them for the hose to clip over.
Well the fact is just about all cars these days are running their
cars on r134a gas.
First off what part of the A/C system isn't working?
Does it just need to be serviced? Out of gas? Electrical? Your
description isn't enough to diagnose.
I'm not sure when they started using r134a gas but i can tell
you that's what they use now.