Not much to say. Pass the 608 (home hvac) or 609 (automotive). Buy the refrigerant at supplier. You can buy an expensive R134a refrigerant recycling system like the one I own for 609, but you can also use a less expensive refrigerant recovery system that's functionally a vacuum pump with built-in manifold gauges and a tank or just a vacuum pump, manifold gauges, and a recovery tank. Easy fixes are on YouTube. I am looking into setting up a refurbishment service for broken AC electronics. To me, it's just a motherboard and I can fix them with my soldering station.