Well I spent 130$ on r12 for my original z28 a/c recharge. I paid 130$ for 3 12oz cans from a shady fella off of craigslist. The mechanic pumped it or vacuumed it up and it has a corroded pin hole leak In the compressor body and the seals are blown. The car was sitting for like 10 years and was wishing I could recharge and go. Long story short, auto zone has a new pancake compressor(what the mechanic said it was called) a accumulator and cycle switxh all for 180$. Will this still be an r-12 compressor or do they only make them in 134? Any thing else I would need? I tried
To find new expansion valve too but I couldn't find it online at the autozone website

 

I believe the vehicle can use the R4 (radial piston) compressor. The compressor should work with either R-12 or R-134a as long as the relief valve is correct. The compressor (refrigerant) oil is what is most important in differentiating between the systems. Use the correct oil for the type of refrigerant and the compressor will operate.

As for expansion control, the system may have used an orifice/choke tube (AC Delco 15-5151) instead of a TEV. That should be replaced since the system has likely been contaminated after being open for so long. They are usually less than ten bucks, but many of these system replacement "kits" include the orifice tube.

Given the cost of the refrigerant, I would suggest initially filling the system with a compatible test gas then checking for further leaks, or at least pulling a vacuum for several hours before tapping into the R-12 supply.