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How Does Air Conditioning Work?

To put it simply, an air conditioner is a refrigerator for your home. It provides relief during those long summer months, regulates the temperature in our homes and businesses, and keeps the humidity out of our homes. But how exactly does air conditioning work?

An AC tech working on an installation

A Brief History

First developed in 1902 by engineer Willis Haviland Carrier to solve a troublesome humidity problem at a publishing company in Brooklyn, New York, the air conditioner quickly became a fixture in many businesses and homes, providing relief to consumers and workers alike.

The problem originally arose when the printing plant couldn’t get ink to transfer properly to the page due to the high humidity caused by scorching summer heat. Carrier’s invention sent air through coils filled with cold water and back out into the plant, cooling the air and removing moisture from it.

By controlling the humidity in the plant, workers were able to effectively print the materials they were attempting to print. Then, in 1933, the Carrier Air Conditioning Company of America developed an air conditioner very similar to the ones we have today in homes, businesses, and other indoor spaces.

Today’s modern air conditioner uses the same science that Carrier’s system used in 1933, but features updates and advancements in compression, controls, and diagnostics, electronic and “smart sensors,” and energy-efficient components.

The Basics

Air conditioning works by removing heat from the indoor air and transferring it outdoors. It does this through a process called phase conversion, where the air conditioner will force a special chemical compound to evaporate and condense repeatedly in a system of coils.


The special chemical compounds that evaporate and condense repeatedly are called refrigerants, which have properties that enable them to change at low temperatures. The air conditioner will move warm interior air over the cold, refrigerant filled coils.

Evaporator Coils

When the hot air flows over the cold evaporator coils, the chemical compound inside absorbs the heat from the air as the refrigerant changes from a liquid to a gaseous state.

Condenser Coils

A/C GuageFor the air conditioner to work consistently and efficiently, it needs to return that gaseous refrigerant to a liquid so that it can continue cooling the air.

It does this by compressing the gas and then expelling the unwanted heat created by that process through a set of condenser coils. As the gas cools, it changes back to a liquid, and then the cycle can repeat itself.

More Than Just an Air Conditioner

An air conditioner does more than just cool the air in your home – it helps to regulate the temperature within your house, acts as a dehumidifier, and can remove allergens and particles from the air through an onboard filter in your air conditioning system. Air conditioning isn’t just a luxury for the modern American – it’s a necessary component of life, and its invention has greatly improved the quality of life for those in the US and the industrialized world.

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