If you have a sound (re;tight) R12 system and just need maintenance, stay with R12 and get a system that works as well as it should by design. If your system is shot, ie; evaporator, compressor, and needs a complete rebuild, maybe an alternative is in order.

Back in the eighties I used to be employed in the res/comm HVAC industry, in those days, we used to "dump" a system by opening a Schrader valve and waiting until the noise stopped, before closing a valve and starting the evacuation process. We had no clue it was not a good thing to do.

Keeping an older R12 system working the way it was designed to is not illegal or un-ethical in any way. It is a good use of materials and resources, recycling or rebuilding is always less expensive than re-manufacturing, at least on a one off production.

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1993 190E 2.6 135k
1989 Ford Thunderbird SC 5 Spd 79K