I don't disagree with your philosophy entirely. Any service done to an AC system must be done right. Leaks, poor service, and any questionable parts must be serviced and/or repaired properly before adding any refrigerant.

I just couldn't disagree more on refrigerant types and the risks with both. I find no logic in the EPA position that HC's are dangerous because they can catch fire and HFC's are safer because they won't, even though HFC's will cause permanent brain damage if inhaled in quantities as low as 4 parts per million. This stuff has no smell at this concentration, so there is no warning from exposure and by the time you realise something is wrong, it's too late!

HC's have a heavy odorant added to them. By the time you smell a problem, the gas concentration has to be 25 to 30 times higher to ignite. This odorant is my safety factor and one I can live with. But I would never recommend anyone just pour in some refrigerant and viola! everything works perfect regardless of what type.

The chemical composition of Autofrost looks promising enough to consider when I'm fully licensed because it requires a permit and it won't burn or deplete the ozone layer, the original reason I tried Envirosafe. Whether we like it or not R12 is going to be gone at some point and we must move on from there. It was my favourite for this too.