When the whole "conversation" about R-12 being harmful to the ozone layer, I always wondered how something in a closed system could harm anything? Only when it leaked out. Supposedly, as the 16 ounce cans were the main way it was sold, the crimp seals on the cans did seep gas out over time, which is how the R-12 "escaped". Many shops bought R-12 in a welding gas-type container, using good valving to keep it from leaking. Later, the 30 pound cans became more prevalent in use. The tech had to make sure the valve was fully closed at the end of each charging session or . . . . $$$$$$ floating in the air.
There were conversations about DuPont's patents running out, then, too. BUT as the USA was the only country to basically outlaw R-12 production, Mexico did not, so smuggling across the borders was known to happen. One GREAT vehicle would have been the early CNG OEM pickups from Ford and GM, with three CNG containers placed cross-ways in the rear frame, where the spare tire used to be. Not sure if that happened, but it looked like it could, to me. There were comments (without evidence) that Mexican R-12 could corrode the system internally, as it was of lesser quality.
It was during these times, when smuggling-in R12 was in the same category as smuggling-in AR-15 style assault weapons (while that was criminalized in a 10-year period, due to gun violence. Yep, it happened and was federal law), that some "alternatives" to R-12 were played with. Including butane. Many people living "in the country" had butane tanks for their homes, so it was readily available. I don't know that any crash tests were done, but it could be imagined to be a big fire ball rather than not. That probably led the EPA to regulate sales of "drop-in" R-12 alternatives, of which there were a few. Some hybrids were closer to R-12 than R-134a, as I recall.
Seems like I recall some comments about R-12 also being flammable? With a "No Smoking" near it, too. Probably not as flammable and "explosive" as butane, though. As I was in the dealership parts biz, I followed all of these things and how the OEMs transitioned through them. I had a good friend who worked for an aftermarket a/c supplier, who was knowledgeable of the initial R-134a research AND how they got past the "lesser cooling" situation of R-134a. Larger and more-efficient condensers usually was the OEM fix. BTAIM
One radio program I listened to, back then, the host testified before a government panel. He stated that if R-12 was globally banned, people in poor countries would die. That got everybody's attention! Then he explained that older refrigeration equipment ended up being in these countries, after it was "old and replaced" in the USA, to keep medicines cold. Another unknown fact. So a global ban on R-12 did not happen. So R-12 is still around, but evolved out of being the main refrigerant used.
R-134a was supposed to be "the best", but we how have r-1234yf as its replacement. Takes less but is insanely expensive, by comparison. Less harm to the ozone layer, but by less of a degree than R-134a is, it seems. Then Scotty Kilmer used some less-expensive R-52 to top off the a/c system in a Honda, in one of his YT videos! The plot thickens!
AND . . . the home a/c system gas has been going through changes too! Only thing is that each of these gas phase-outs means NEW EQUIPMENT, it seems! We thought the automotive a/c stuff was crazy!!!
Just some thoughts and observations,
CBODY67
