How Does Air Conditioning Work

Before we dive into how AC works, we travel back to 1902 when Willis Carrier invented the first modern AC unit. This revolutionary product transformed numerous industries that continue to impact our world today. While air conditioners today have different features and capabilities compared to older models, these systems still operate on a few basic principles. So, how does an air conditioner work?

AC units come in a variety of shapes and sizes, but they all operate in a similar manner. The basic principle of these systems involves how they eliminate heat and humidity from an indoor air. These units push cool air inside while transferring unwanted heat and humidity to the outdoors. The average AC unit today uses a chemical called refrigerant. This is what helps to create cool indoor air.

These three system components work collectively to convert refrigerant gas to liquid form, then back again. While the refrigerant starts in the compressor to raise temperature and pressure, it then travels to the condenser coil where it's made into a liquid. The refrigerant then goes back indoors to the evaporator before the liquid evaporates and cools the indoor coil. A fan will then blow indoor air over the cold evaporator coil, which allows warm air to be absorbed by the refrigerant. While a fan blows the cool conditioned air throughout the indoor space, the heated evaporated gas is pushed outdoors into the compressor. As the refrigerant returns back to its liquid state, the collected heat is released into the outdoor air. This process will continue until your home or business has reached its desired indoor temperature.

The average home in the United States uses a central AC system to keep families cool and comfortable. Also referred to as split-system air conditioners, these units include several components that offer more than air conditioning; some systems can also regulate humidity, airflow, and air quality within a space. Before diving into how does an AC work, let’s look at the various parts that make these systems function.

The average central air AC unit includes the following:

• A thermostat that controls how the system operates
• An outdoor unit that includes a fan, condenser coil, and compressor
• An indoor system that has an evaporator coil and fan that circulates the air
• Copper tubing that holds refrigerant that moves between the indoor and outdoor systems
• An expansion valve that controls the amount of refrigerant that enters the evaporator coil
• A series of ducts used to move cooled air throughout an indoor space and back to the indoor system

The common AC unit actually works a lot like your home refrigerator. These two essential home systems move heat from the indoors and push it outside where the temperature is warmer.

The following two processes occur simultaneously, one indoors and one outdoors:

Sometimes called the “cold side” of the unit, this is when warm indoor air blows across a cooled coil that’s full of refrigerant. At the same time, heat from this indoor air absorbs into the refrigerant as it turns into a gas form. This cooled air is then pushed through the indoor space to supply comfort.

Given how indoor spaces come in several shapes and sizes, there are a few different types of AC units on the market. These include:

• Split-system air conditioners
• Packaged AC units
• Ductless cooling systems

Knowing which system is right for you depends on your space, climate, and preferred comfort level. Whether you’re looking to buy a new AC unit or you’re just curious about how these systems operate, understanding how they work can be very useful.