What we have here is yet another excellent video from YouTube's Engineering Explained, a delightfully nerdy series wherein host Jason Fenske breaks down complex automotive systems and explains them in a simple, visual way that you'll totally understand.
This air conditioning explanation gets a little technical at times—Fenske uses symbols for pressure and temperature that you probably haven't seen since high school chemistry. All that you really need to remember is this: Any time a compressed liquid is released and turns into a gas, the process absorbs energy, meaning it sucks in heat. That's why the propane gas bottle under your grill gets cold to the touch while you're cooking.
There's a tiny catch to this video: It's basically one long commercial for AC PRO, an air conditioning recharge kit. But if your car's getting older, it might be time to recharge your air conditioning anyway, and Fenske's explanation of how to do that is stone simple and makes the whole thing look easy. You don't have to buy the brand of AC refrigerant he's selling—the information is free.
Anyway, here's exactly how the air conditioner in your car (or your house, or your refrigerator, or your freezer) works, and how to DIY recharge it. With a hot summer ahead, this knowledge will keep you cool.