Well, they were right, R12 systems cannot be repaired. Even IF they have access to R12, the EPA outlawed R12. They would have to replace the entire system to convert to the current refrigerant, including the Evaporator and condenser since they are incompatible with the new stuff. What is compatible is R134a, but not meant for appliance use, but you would still need a compressor so back to square one. Been down that route myself as I wanted to repair an older one we had, could get parts, but not the refrigerant. All my stuff is R134a compliant, but only for automotive use. I still have a can of R22 for home AC units.
Speaking of AC units, back in 2001 when we moved to our current house, the PO had a room addition put on, but no HVAC was installed, they would winterize the bathroom and seal it up in the winter, it was pretty much unfinished. In 2002, Home Depot still sold DIY HVAC so I bought the proper sized furnace and AC, a Hamilton, installed all the ductwork and the units, and the wiring myself. During that time up until today, the only issue with the furnace was a bad capacitor on the blower motor. $30 replacement. The AC had stopped working, of course on a hot humid day with plenty of skeeters in the air. Found a mouse nest and a chewed wire to the relay. Fixed that. Following year, another mouse, no nest since the stupid critter shorted the capacitor and fried. This time had to replace the capacitor and relay as the contacts were worn.
Last year same thing, same time of year, but chewed wires to the relay. So it has a new relay, new capacitor and new wires, this time I left the damned cover off. This year, no more mouse issues in the condensor, instead the little bastards got in the house, along with some rats. Isn't country living great! I am in the process of ripping out some walls in one room that used to be a garage, I found where they were entering the house, under the garage slab, chewed through a 2x4 and sheathing, and then through a corner of the drywall that was behind shelving. Needless to say, no more have been able to seek shelter from the cold. Those things are so destructive too. By the time you realize they are in, they have already done the damage. We always had mice issues, but the cats have taken care of them for the most part, the rats were a new thing, up until last year we never saw one, and been here 20 years. I think they are coming from a farm down the road that had just put up new storage buildings and store seed they grow.
After 20 years here, I could fill a book on all the projects and repairs this place has had done. It's like that house in the movie Money Pit. Yes even the tub falling through, well almost. There were two cast iron tubs back to back, whoever did the plumbing notched out the joists, there is barely any wood holding the joists up now, and to top it all off, had put in a room underneath as a laundry room, and installed a pocket door under the main beam. To make it fit, the idiots notched the beam which is made up of 4 2x10's nailed together. That part of the house now pitches towards the center by an inch. I had to build a 2x6 wall under the beam to keep it from going any further. 20 years, still not done doing repairs.