Factory AC can work great with R-134A if you know a few secrets

If worried about R-134A, a drop-in replacement for R-12 are hydrocarbon refrigerants (propane & isobutane mixtures?). I have used Duracool in all my vehicles for decades. Envirosafe is another. HC works slightly better than R-12 and is compatible with all oils. If flushing everything, Hella's PAO 68 is the best oil for any refrigerant. It improves efficiency and doesn't absorb moisture like PAG does. There is concern with HC being "explosive", which is absurd if you understand combustion, yet reporters and hobbyists rant about that. No fire reported after use in millions of cars for many decades. All refrigerants with the accompanying oil spray can burn when punctured, and newer ones (R-134A & R-1234yc) form deadly poisonous gases when they burn. R-134A has long been outlawed in Europe and Canada, and soon in the U.S. R-1234yc is quite expensive and I don't know if conversion is possible or practical.