[dublin]

I contacted him a number of years ago about his R-12 replacement for my old 1975 Ferrari, rather than converting it. It worked perfectly - better than Freon-12, even. Which is the only reason the EPA refused to allow it to be widely used. His web site (ghgcool, IIRC, I'm sure long gone by now) taught me that you can also mix butane and isopropane as a superior drop-in substitute for R-12, but he didn't pursue that approach because he knew that the EPA would kill it on safety grounds - even though it was only slightly more flammable than R-12 with the required compressor oil mixed into it.

George was a really interesting guy, a true hacker's hacker, and I truly enjoyed talking with him.

[burnt-resistor]

There is no grand conspiracy. Every major gaseous hydrocarbon also tend to usable as refrigerants but tend to be extremely flammable, while most every chlorofluorocarbon tends to inflammable but extremely toxic under deflagration forming nerve agents like phosgene and acid vapors like HF and HCl. Thus, the primary tradeoffs are cost, flammability safety, deflagration safety, ozone destruction potential, and global warming potential.

The problems of conversion include in/compatibly of lubricants and refrigerants with seals and the density, boiling points, and latent heat of vaporization of replacements. The R-12 to R-134a conversion process was simpler but typically included different lubricants, orifice, and o-ring seal materials. I don't see how R-12 to a hydrocarbon or admixture of R-290/600a isn't a magical tall tale without proper math, equipment, and understanding of HVAC operating principles.

See this PDF for a summary: https://www.colmaccoil.com/media/394090/refrigerant-guide-fi...