Well, first you need to pierce a line, and recover the R-12. You do have a piercing valve, recovery pump, and a cylinder for R-12? Don't just blow it out, and risk the 5 year, $25,000 penalty. Second, you get your acetylene torch and unbraze the couple fittings on the old compressor. Unhook the electric wires to the old comp. Get your silver braze flux, and your sand screen, and polish up the copper lines that go to the comp. They won't be in the right places, so just braze or silver solder on a couple of couplers, to lengthen the tubes with copper ACR tubing. Set the new compressor in place. Silver braze, or silver solder the suction and discharge lines. Cut to length, and then use sand screen, and fitting brushes to polish the copper to copper connections. Braze or silver solder an access fitting to the process stub of the comp. When it cools, remember to put the valve core in. Cut the discharge line (now that you have it steadied by being soldered or brazed on both ends) and braze in a filter drier. If there is an old one, remove it. Atach your vacuum pump and manifold. Run it down to about 500 microns. Deeper vacuum is better. Get your charge weight scale out, and weigh in some new refrigerant. Should be pretty close to the R-12 charge weight. Turn on your leak detector, and beep for leaks. Wire in the electric power wires. Turn refrigerator on, and you're good to go. So simple, even *I* could do it! I've done several refrig compressor change outs.