Random AC question

Not a big problem with R-12, though the mineral oil does absorb a little moisture. If you had R-134A, the PAG oil strongly absorbs moisture to form corrosive acids. Regardless, keep the tubes capped off if you unbolt. Don't leave open to the air for more than a day. I wouldn't change to R-134A since being outlawed. Why not a HC refrigerant like Duracool or Envirosafe. Works slightly better than R-12. People who claim it can explode are fools with no understanding of combustion. All refrigerant leaks can burn from the oil mist, though bigger problem is the condenser gets ruptured in an accident and refrigerant gets sucked in the running engine to come out the exhaust burnt. That makes poisonous phosgene gas with R-134A (WWI) and even worse HF acid with the new R-1234yc. Firemen learned to stay away from the exhaust after a crash. PAO 68 is the best oil for any refrigerant. Replace old hoses with new "barrier hose". If no ferrule crimper, you can get a slick look with Oeticker stepless ear clamps (ebay).

BTW, the whole Ozone Hole thing was a useless fuss. Negligible CFC's are measured in the stratosphere above Antarctica, yet the OH has been larger than ever since 2019 when it had shrunk and U.N. crowed "fixed it". It only occurs over Antarctica in Winter when little sun anyway, so the fuss seemed silly. Most reports of increased uV damage proved apocryphal. If you accidentally vent a little R-12, the planet will survive.