yes, low temp R-12 and weber cases
Just changed out a valve plate on a 3ah-0200-tac unit, s/n 70d...., freezer @ -20 setpoint, R12 system still running in it. Wouldn't have to do that if the store would of kept up with maintenance and all. They let the unit run (at 10 degree ODA temp, 100 ft line set) with no evap fans for a few days. Finally went warm and they called us.
Broke suction reeds and discharge valves leaked. Pumped down to 18" quickly but came right back up, when I did a valve leakage test. Found some copper plating going on in it but, to get more life out of unit we put on a new valve plate. Oh, it was the original valve plate to. 37 years old wow.
Did I see a set of digital yellow jacket gauges here? Nice!!!!;)
I remember the biggest problem in the changeover from the big 3 refrigerants, R12, R502 and R500 wasnt so much adapting to the many many alternates that came on the market, but it was more in the recovery equipment and processes. The technology really wasnt there.
We came up with all kinds of schemes to cool down the recovered refrigerants for the process and then heat them up in the equipment to pull it out.
One of the first recovery units we built was a semi hermetic 1/2 hp unit, tried water cooled with a hose and separate condensing coils, water jackets on the compressors and more. Imagine hauling that stuff on a roof. Changing the oil each time or adding as the valves began to fail. Back then recovery units that worked half ass would cost about 4 Gs and weighed 3-400 pounds.
Half way through recovery we were often looking over our shoulders to make sure no one had a camera on us while we calculated what deminimus meant.
MP 66 has more capacity and compressor temps run lower. MP66 iss a Win Win refrigerant alternative for R-12 .
The same should be said about HP80 (R402A). great low temp refrigerant, and compressor runs lower in temps, another win win. It is reccomended that these refrigerant have a A-B synthetic oil employed with there use, oil types and SU values should be considered for type of compressor or what the Compressor oe suggest for use.