by Sam E. Jones

Created on: July 27, 2010

Sometimes the things we see in our lives just do what they do and we are none the wiser; but other times we look at something and ask ourselves, how does that thing do what it does? One of those things is an air conditioner. How the heck does it sit there on a hot day, and make cold air blow into your house or apartment?

The fact is, it’s not all that complicated, and it’s actually one of the things in science that are really well understood; at least up to a point.

Before explaining how the whole thing works, you have to be able to accept the fact that if you pressurize a gas it becomes hotter, that’s just one of the things that happens in nature. This is because when gas molecules are pushed closer together the energy that was previously being used by them to maintain their distance from one another is converted to heat. Conversely, if you lower the pressure of a gas, allowing it to expand, it becomes cooler. That’s the basis of the whole refrigeration thing.

Air conditioners work by using a special kind of gas called Freon that is amendable to pressurizing and depressurizing in a closed loop system whereby it becomes a liquid at a relatively low temperature. Hardware devices are then used to pressurize and depressurize the gas so that it gets hot and cold alternately. The first of these is called the compressor, because it compressors the gas. It does this by allowing the gas to flow freely into a chamber and then shoving in a piston to make the available space smaller. Since the gas has nowhere to go, it gets squeezed into a more condensed form, which means it gets hotter as described above.

Next, the gas is pumped to the back of the air conditioner though small coils where air blows over it to cool it down and turn into a liquid. Note that the pressure that was caused by the compressor is still in effect, that’s why the Freon turns from a gas to a liquid when it cools, because it is still pressurized.

The whole point of this first process was to get the Freon to turn into a liquid so that it could be used as a liquid in the second part.

The compressed liquid Freon is then squirted through a small nozzle into a closed chamber (once again comprised of small coils) and immediately expands to fill the allowable space; it’s this sudden expansion that causes the Freon to suddenly get colder.

After that, all that’s needed is to blow air across the chamber coils to push the cool air off the exterior chamber surface and into your home.

The Freon is then routed to the back of the air conditioner unit and the whole process is repeated over and over.

And that’s how an air conditioner works.

NOTE: When the Freon expands and gets colder it is actually removing heat from the surrounding area, rather than generating coldness, and that’s why people say that air conditioners cool your home by removing warm air, rather than by generating cold are and blowing it in your house.

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