I've been recharging the AC system on my vintage daily driver — a late 1960s Mercedes-Benz sedan — with common off the shelf campstove propane for 30 years. Keeps me cool regardless of outside Los Angeles heat. Requires a bit of care while doing a recharge, but it's nothing too crazy. My grandfather ran a dairy farm in Connecticut, he showed me this trick in the 80s. We used propane to keep all the cooling equipment in the milk houses running smooth back then. I'm curious about isobutane now.