Technician Installing Residential HVAC Central Air Conditioner

How Does Central Air Conditioning Work?

Residential air conditioning is one of the greatest inventions of our time. Not only does it cool or heat the air, but it also filters and humidifies if needed.

But if you’ve ever wondered how does air conditioning work, here’s a quick answer:

In simple terms, central air conditioning units run on the same technology as your refrigerator. They use gas to transfer heat from one place to another, effectively cooling the space down. The HVAC system then blows this cold air around your home.

Of course, a residential air conditioning unit’s inner workings are a bit more complex than that. In this article, we’ll cover exactly how an air conditioning unit works along with the benefits of having one in your home.

What you’ll learn in this article:

How does Residential HVAC Work?

A residential air conditioning unit – also known as central air – will consist of the following main components:

  • A thermostat to control the temperature
  • An outdoor unit that contains a fan and a compressor, or condenser coil
  • An indoor unit that includes the evaporator unit and fan
  • Tubing between the indoor and outdoor units
  • Expansion valve
  • Refrigerant
  • Ductwork around the house

The process essentially draws heat from the area you want to cool (the indoors) and passes it through the outdoor unit’s tubing.

Let’s break it down into the main steps:

  1. The thermostat registers the air has reached the pre-set temperature limit, kick-starting the HVAC system.
  2. The air-handling unit starts up and draws air from inside the house into the ductwork.
  3. This air passes over a cooling coil, which is full of refrigerants.
  4. The refrigerant absorbs heat from the air as it turns from liquid into gas.
  5. The air, which is now cool, is circulated back around the home through the ducts.
  6. Simultaneously, the refrigerant (now a gas) passes through the compressor before making its way into copper tubing.
  7. This tubing is in the outside unit and allows the refrigerant to release heat.
  8. It also passes through the expansion unit, which turns it back into a low-pressure liquid.
  9. The outdoor unit houses a fan, which pulls in air to eject the built-up heat.
  10. The process repeats until the thermostat registers the AC optimum temperature and clicks off.

One of the essential components in a residential HVAC unit is the refrigerant. It’s converted from a low-pressure gas into a high-pressure liquid during its journey through the unit. This process causes it to absorb heat from the warm indoor air and expel it outside.

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Types of Residential Air Conditioning

There are three main types of residential HVAC units, all of which have different applications depending on your home’s size. They are:


This system is the type of unit described above, which has an indoor and an outdoor unit. These are suitable for homes of pretty much any size but are typical in multi-room buildings.

Packaged system

These are all-in-one units that contain the evaporator, fan, compressor, and condenser in the same unit. They’re suitable for situations when a property doesn’t have enough room for a split system’s indoor unit. For example, you might find a packaged system in an apartment.

Ductless system

While not technically a central air conditioning unit, ductless systems can help cool specific rooms. They typically work like a split-system unit but don’t have ducts for circulating air around the home. Ductless systems are helpful if you want different temperatures in different rooms, such as a warm office but a cool bedroom.

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Why Residential Air Conditioning is Beneficial

The reasons why your home would benefit from central air might be obvious: it cools the air down. But the benefits of having residential HVAC go beyond this, as we discuss below.

1. It filters air

Residential air conditioning comes with filters that trap airborne particles, such as lint and dust. While this is mainly for the system’s benefit, it can help you too. You can use HEPA filters on residential HVAC systems, which is ideal for anyone suffering from allergies. Importantly, these filters also remove airborne pollutants that can damage your health.

2. It provides heating too

The H in HVAC stands for heating, so it’s hardly a surprise that the unit provides heating too. The system will usually be connected to a boiler or heat pump, making it easy to heat and cool your home with the same system.

3. They last a long time

HVAC systems can last for decades, providing you get the proper AC maintenance. It would be best to have your unit serviced once a year to keep it in optimum condition. But if you do, it’ll serve you for many years to come.

4. Energy efficient

Modern residential HVAC units are incredibly energy efficient, which will help to reduce your bills. Intelligent systems can even target individual rooms, meaning you don’t have to waste energy heating or cooling rooms you’re not using.

5. Good return on investment

If you don’t already own a central air conditioning system, it might seem like a significant investment. But not only is it more cost-effective than other heating methods, but it’ll also add plenty of value to your home, bumping up the price when you come to resell it.

6. Better home security

This reason might seem a little out there, but having a residential HVAC unit can improve home security. Using air conditioning means you don’t need to keep your doors and windows open on a hot day, which will make your home a safer place.


Your HVAC maintenance appointments should work around your family’s schedule. For nearly 50 years, KCR has provided residences and businesses with peace of mind and temperature control. We’re proud to serve our customers with efficiency and flexibility in managing your efficient home heating and air conditioning.

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