How air conditioner works
How does a electric air conditioner or refrigerator work?
By boiling any liquid, heat is absorbed by the liquid phase change into a gas.
This is true with a pot of water on your stove consuming about 1,070 Btu's of heat to change each pound of liquid water into steam vapor, or with any substance changing from a liquid to a vapor form.
Back in the early 1900's, CO2 was a popular gas used to cool buildings, however it was very toxic to the occupants if a leak happened, it might suffocate a whole theater full of potential repeat customers. Dr. Carrier developed a line of less toxic refrigerants, with much lower compression requirements, including the popular R-11, R-12, R-22 and several others during the 1920's and 30's.
How they work is within a sealed system, the freon is boiled at a low pressure, and air is blown past this very cold freon filled tubing, producing the desired cooling effect. With unlimited supply of refrigerant, there would be no need to recycle the freon. However with a limited supply on hand, the 1 to 15 pounds of freon is recycled many times each hour by changing the boiling point of the freon from 40F used in air conditioners or -5F used in your home refrigerator to 90+F by compressing the gas and forcing it into a condenser, that will give off heat to the air (or a water loop) in a location acceptable to the designers. Blowing air across the condenser that is cooler than the freon inside will change that freon back into a liquid, ready to start the whole process all over again.
Freon might be the most recycled item in your kitchen, with each pound inside the refrigerator recycled from a gas to a liquid, back to a gas again over 50 times per hour. In 20 years average service life, the freon will change phase from gas to liquid and back well over 3 million times. This makes freon second most recycled liquid next to the water coming out of the faucet.
New freons are being developed to replace the ozone depleting freons, and a phase out of the old freon R-11, 12, 13, 22, 500, 502 and many others has already been well underway by the year 2010. The replacement refrigerants are R-134A, 404, and 410A, (among others) that tend to be much more energy efficient as well as friendly to the environment.