I would cry BS on the statement that no shop will touch your A/C system after conversion to Freeze 12 or Freezone. There are tons of shops that will do the work...& even more individuals. Just typical propaganda put out by the makers of $3500 reclamation machines & volume selling 134A conversion kits. Think of it this way, if there is nothing in the system to recover
what can contaminate their d#mn machine.
Having "reconverted" several vehicles ('87 Cutlass, '84 Chevy pickup, '86 Suburban, '90 model LandCuiser) off previous 134 conversions, I'll never convert anything anything to 134-A. Last summer, my stubborn brother converted his LandCruiser to 134-A, it wasn't 5 days & that crap was out, flushed, Freeze12 & new oil in. Result...ran close to 20 defrees cooler & my sister-in-law was off the warpath!