Edit: Got mixed up with R-12, which was used in cars and apparently runs at a lower pressure. I looked into an R134a conversion for my 1990 car about 10 years

Edit: Got mixed up with R-12, which was used in cars and apparently runs at a lower pressure. I looked into an R134a conversion for my 1990 car about 10 years ago and found that any remaining R-12 would need to be vacuumed out of the system and collected for re-use. I elected to just live without A/C for a few more years and let the junkyard collect the refrigerant when I ended up scrapping the car.