R134a not nearly as cold as R12 .
My '91 Honda CRX Si with R12 refrigerant, would put out air at around freezing, 32 F, 0 C .
My '14 Hyundai Veloster with R134a, at best 50 F, 10 C during our ' hot season ' .
My '01 BMW Z3 with R134a, about the same temps as the Veloster .
Pressures on an R143a system run higher than an R12 system .
I recently ' scored ' 15, 12 ounce cans of R12, for $150 from a person that had no idea what they had .
I need to get the A/C system on my '79 Pontiac Trans AM up and running, never been recharged since I bought it in Oct., '79 .