system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How does an A/C unit cool hot air so quickly?
gpt
When a gas is presurized, it heats up. The inverse of this is that when a gas's pressure is reduced, it cools down. An AC machhine forces a gas to compress, which then heats up. It gives heat to the air around it (hopefully outside the space you want to cool) and thus loses total heat. The gas then goes back and expands, cooling down a lot, and *cools* the air around it, which *is* blown into the space you want to cool.