“Understanding Home AC Systems for Beginners: How It Works”

Understanding the Basics of How an Air Conditioner Works

Hey guys, Jay here with Word of Advice TV, and in this article, I’ll be explaining how an air conditioner works in the most simple and easy-to-understand way possible. I’m an HVAC technician, and I work on residential furnaces and air conditioners like this bad boy right here. Oftentimes homeowners ask me how an air conditioner works, and I’ve tried to perfect the art of explaining this complex topic in a simple-to-understand fashion.

What is Air Conditioning?

The term ‘air conditioning’ simply means to condition the air in a set area. In the case of an air conditioning unit, what we’re doing is taking heat from a place where we don’t want it and bringing it to a place where it doesn’t bother anybody. In other words, we take hot air from inside the house and dump it outside.

Understanding the Two Parts of an Air Conditioning Unit

It’s important to realize that an air conditioner is a two-piece deal: the outdoor condenser unit and the indoor evaporator coil. The indoor coil, often called an A coil, typically sits on top of or below the furnace, or on either side if your furnace or air handler is horizontal.

The Physics Laws of Heat Transfer

To understand how an air conditioner works, it’s essential to know one physics law — heat travels from hot to cold. The larger the temperature difference between two objects, the faster the heat transfers.

Using Refrigerant to Transfer Heat

The key to how an air conditioner works is the use of a refrigerant, often called freon or coolant, which is a cold substance that gets circulated between the outdoor condenser unit and the indoor evaporator coil. The compressor, located in the outdoor unit, pumps the refrigerant, and as the refrigerant travels through the indoor coil, the air from the furnace or air handler blows across the coil. As the air goes past the cold coils, they absorb the heat, decreasing the temperature of the air.

How the Outdoor Unit Works

When the refrigerant, now full of absorbed heat, travels back to the outdoor unit, it goes into the compressor, which compresses the refrigerant, increasing its pressure and temperature. The refrigerant then circulates throughout the outdoor coil. The fan on top of the unit sucks air from the sides and pushes it out through the top, absorbing the heat in the refrigerant as it passes through the coils.

Returning the Cooled Refrigerant to the Indoor Coil

As the refrigerant passes through the outdoor coil and cools off, it goes back inside the house. Before it goes into the indoor coil, it passes through a metering device, which depressurizes the refrigerant, allowing it to return to its cold temperature. This loop of transferring heat from inside the house to outside then continues, which is how an air conditioner works.


In summary, the outdoor unit needs to have coils that are hotter than the air outside, and the indoor coil needs to be colder than the air inside the house. This whole process is achieved by the refrigerant, which continuously circulates between the indoor and outdoor units. I hope this article has helped you understand how an air conditioner works. Please leave your feedback in the comments section below.

Puzzle Time

For those who made it to the end of this article, here’s a puzzle for you:

The objective is to move one nickel one time to get each row to have five nickels in it. You have 30 seconds before I reveal the answer. The solution? Take the nickel at the end of the row with four nickels and place it on top of the fifth nickel in the row of five. Now, both rows have five coins in them. If you solved it, then congratulations! You’re in the minority.

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