What is the function of an AC compressor?

Answer 1

Air conditioning can be thought of as a kind of 'heat pump'...moving heat from one area to another. When a gas is compressed heat is generated and the temperature of the compressed gas rises. When a gas loses pressure heat is lost, and the temperature of the (now less-compressed) gas drops.

So the compressor of an AC system in a car takes AC gas and, yep, compresses it. This takes place in the engine compartment, so (unwanted 'waste') heat is added under your hood. But the compressed gas then flows through the AC lines to an ac unit under your dash, where it goes through an oriface and pressure is released (think of spraying water out of a hose...the water in the hose is compressed, the spray of water outside your hose nozzel is de-compressed.). Although it goes through an oriface, the gas/fluid is not released into your car interior, the entire AC system is a 'closed' system...the AC fluid is used over and over...compressing and getting hot under the hood, decompressing and getting cool inside your passenger area, but still retained within the AC "Plumbing."

When the AC gas/fluid goes through the oriface and is less compressed, it gets cold. Air being pushed through the AC unit (kind of like a little radiator) under your dash is consequently cooled, and voila, cool air comes out your dash vents.

In effect the result is heat has been moved from inside your passenger area of your car to under your hood.

Hope that helps answer your question, Paul.

PS: I may not have used all the right terminology, but I'm pretty sure I'm on track with the overall theory of how it all works.