I've curious about how an air conditioner or refrigerator make's cold air. I've read two different descriptions how cold is "made", or how heat is removed from a system. Some descriptions Ive read say that air conditioners use expanding gas in it's coils, hence the use of Boyle's law. Other descriptions I've read describe forced vaporization of a liquid, in which case heat would be absorbed from the surroundings due to the enthalpy of the liquid vaporizing. They seem like mutually exclusive actions, as for using Boyle's law the refrigerant would get cooler, but using the method of vaporizing a liquid, it seems the refrigerant would absorb more heat, and be more effective at cooling. Anyways, my question is which law governs the cooling action?