Do You Know How Air Conditioning Works?



By: John Miller

5 Min Quiz

Image: shutterstock

About This Quiz

Long ago, in the days of dinosaurs and misery, there were homes with no air conditioning. Each summer, as the Great Yellow Sky Demon set the world aflame and humidity left human beings smelling like salty flesh bags, our species learned to slow down, do nothing at all, and pray for cooler weather. Then, at the dawn of the 20th century, our race evolved into a glorious new era – the age of air conditioning. In this super-cool quiz, do you really think you know how air conditioners work?

The invention of air conditioning is largely credited for the widespread settlement of states like Texas, which were previously largely uninhabitable from May through October.

If you’ve ever hugged your air conditioner and thanked it for its service, you’ve probably wondered what goes on inside this marvel of humankind. Suffice it to say, there’s no ice involved, nor are there wizards from the Arctic imprisoned within its confines. Instead, these machines actually rely on some basic physical principles to cool your home. Do you understand the fundamental scientific functions that drive your A/C unit?

Furthermore, for all of their icy triumphs, air conditioners aren’t really all that complicated. They have fans, coils, and special chemicals that drive their features. Cool off with this air conditioning quiz now!

Who invented the modern electrical air conditioner?

In 1902, Willis Carrier, an American engineer and the savior of our entire species, invented electrical air conditioning. Life would never again be the same, particularly for anyone unfortunate enough to live in tropics-like locations.


Which of the following is NOT a function of modern air conditioners?

The kids won't leave the thermostat alone no matter how often you yell at them. The most important functions of modern A/C are to reduce the moisture and temperature of interior air.


Modern A/C units require which substance?

All modern A/C units rely heavily on a refrigerant in order to perform their cooling duties. Refrigerants vary depending on the manufacturer and region.


Which of the following components is NOT part of an air conditioner?

There's no dryer in an A/C unit. But to be fair, the machines do make the air feel "drier" as they work their magic.


What's a special characteristic of the refrigerant in an A/C unit?

Refrigerants are specially formulated for air conditioners. Their primary trait is that they can quickly change from gas to liquid and back again throughout a long, hot day.


What happens when a liquid converts to a gas?

When liquids convert into gases, they have a useful property … they absorb heat. That principle is the basis for modern A/C contraptions.


In A/C units, refrigerant is circulated through what?

Air conditioners circulate refrigerant chemicals through a series of metal coils. These coils provide a means for the chemicals to undergo their vital phase changes.


What happens to the machine's refrigerant as it passes through the evaporator?

The refrigerant passes through several stages during the cooling cycle. As it passes through the evaporator it, of course, evaporates.


After they evaporate, the refrigerant chemicals then do what?

The unit's refrigerant evaporates and then condenses, over and over again. In the process, it helps cool interior air.


What's the purpose of an evaporator coil?

Evaporator coils contain chilled refrigerant. That refrigerant absorbs heat, and then cycles back through the system.


Where does the refrigerant go after it absorbs heat from your home?

After refrigerant absorbs heat in the evaporator coil, it circulates to the condenser coil. The condenser is outdoors, where it can release excess heat.


How do air conditioners distribute cooler air?

Once the A/C unit conditions -- cools -- the air, it must force it back into the area you want to chill. It uses high-speed fans for that task.


In an evaporator coil, refrigerant moves into which state?

In the evaporator, refrigerant turns into a gas. In doing so, that "phase conversion" allows the chemicals to absorb heat.


What was one problem with older refrigerants?

Refrigerants are not always environmentally friendly. Older types, when exposed to air, would damage the Earth's ozone layer, creating a whole range of potential problems for plant and animal life.


What happens to the refrigerant as it travels into the condenser coil?

The heated refrigerant is a gas when it hits the condenser coil … and then it releases its heat and becomes a liquid again. It's a simple but efficient cooling solution.


What's the name of a very common refrigerant?

It is chlorodifluoromethane. It is R-22. It is what allows you to breathe indoors in North Carolina in August. It's also being phased out in modern countries due to environmental concerns.


What does the compressor do to the refrigerant?

The compressor takes the vaporized refrigerant and increases its pressure and temperature. Then, that refrigerant is sent off to the condenser.


How is the excess heat from the condenser carried away?

As the heated refrigerant travels into the condenser, air passes over the condenser coils. That air carries off excess heat.


The effectiveness of condenser coils can be greatly increased through which means?

Condenser coils cool well with air flowing over them. But they are even more effective if cool water is circulated over them.


From the condenser coils, the refrigerant travels to which component?

The condenser pressurizes and heats the refrigerant. Then, the refrigerant moves toward the expansion valve.


What does the expansion valve do to the refrigerant?

After being heated and pressurized in the condenser, the refrigerant hits the expansion valve. There, the chemicals quickly drop in pressure and temperature in what's called "flash evaporation."


What was one major problem with the very first refrigerants?

How badly do you want to cool off on a hot July day? Badly enough to risk using incredibly flammable refrigerants in your house? That's what people did, sometimes with fatal results.


In the wrong hands, what's a potential problem with flash evaporation?

A/C units rely on flash evaporation to quickly turn the refrigerant from liquid into gas as part of the cooling process. But uncontrolled flash evaporation can be hazardous -- it can lead to explosions.


How is warm interior air moved toward the evaporator for cooling?

The machine uses fans to circulate hot interior air across the evaporator's coils. Then, the evaporator absorbs that disgusting heat and blasts it outdoors.


True or false, do the evaporator and condenser occupy the exact same physical space?

False. The condenser and evaporator are housed in discrete portions of the machine. Otherwise, one would warm the air and the other would cool and nothing would improve your living circumstances.


What happens if you reverse the A/C unit's compressor?

It's called a heat pump -- it's the opposite of an air conditioner. And it can warm your house during wintertime.


Why did the adoption of air conditioners slow in the 1930s?

Willis Carrier's invention became more refined in the 1920s and was set for a revolution. But then the Great Depression hit, and no one could afford air conditioning … or even mortgages.


Modern air conditioners are designed to create what level of indoor relative humidity?

Too dry and your lungs will dry up; too much relative humidity and you'll feel sad and soggy. Modern A/C units create an RH level of around 50%.


What percentage of Americans have air conditioners?

Roughly 87% of America homes have A/C. The only people crazy enough to go without A/C live in Alaska.


Air conditioners also serve which function?

By reducing the temperature of interior air, A/C units also force that air to lose some of its moisture. That makes them dehumidifiers, too … and they make summertime much, much more bearable.


Explore More Quizzes

About HowStuffWorks Play

How much do you know about dinosaurs? What is an octane rating? And how do you use a proper noun? Lucky for you, HowStuffWorks Play is here to help. Our award-winning website offers reliable, easy-to-understand explanations about how the world works. From fun quizzes that bring joy to your day, to compelling photography and fascinating lists, HowStuffWorks Play offers something for everyone. Sometimes we explain how stuff works, other times, we ask you, but we’re always exploring in the name of fun! Because learning is fun, so stick with us!