The EPA and the airconditioning industry get together to force the change of a/c units because they no longer make a/c that can run the old coolant.
Amtrak— has a WAIVER— to use R-12. A federal waiver and a large stockpile for airconditioning trains.
R-12 went away from 1989 vehicles last use onwards. the r-22, then R-410. and soon R-134a to ... what.
And all about the “ozone layer” that has NOT gone away.
Smart engineers should design simple ammonia based coolants that people can use in a self-build system.
Note also that the fedgov certainly gets away with using some of these banned coolants. All for them and not for us, ever.
“R-12 went away from 1989 vehicles last use onwards.”
Close.... 1993 was the last year for R-12 automotive A/C systems.
1993 was the last year for R-12. I’m EPA certified for auto air and can still but and use it. Have to use a recovery machine though. I have two of them, one for R-12 and one for R-134a and also a tank for each. Can’t mix them.
The only two A/C system differences is that the old condensers don’t work well for R-134a and the R-12 seals will deteriorate with R-134a. Newer seal material for 134a will work fine with R-12.
There are R-12 equivalent refrigerants out there like FR-12 that Penzoil came up with.