Had this FJ60 about a month and discovering that just about everything is original. PO really didn't do anything to it, so no surprise to see we have the original AC compressor. But after cleaning the engine, lol, we noticed a new fitting... Does this mean he upgraded from r12 to r134a?? All he said was "the AC doesn't work" - we assumed it needed refrigerant, but assumed it was still r12. Is there any way to check without taking it to a shop? Any danger in adding r134 if we're unsure? TIA!