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How Does Central Air Conditioning Work? A Minnesota Tech Explains

tips and definitions

Air conditioner troubles in the middle of a Minnesota summer is something no one wants to deal with.

But having a basic knowledge of how your central AC works can help you identify and possibly even fix the problem on your own.

To show you exactly how an air conditioner cools your home off, we’ll go over:

  • How air conditioners use heat transfer to cool your home
  • What refrigerant is and how it transfers heat
  • The steps of the air conditioning process

Air conditioners work by transferring heat

The air conditioning process relies on the 2nd Law of Thermodynamics

(Don’t worry, we won’t get too geeky on you.)

All you need to know to understand the basics of air conditioning is that heat naturally flows from a hotter area to a colder area.

Think of a cold glass of water placed outside on a hot day. The glass will bead up and eventually lose it’s “coldness”, right?

Well, the glass loses its “coldness” because the hotter area (the outside air) naturally transfers its heat to the colder area (the glass).

The glass is basically a sponge, absorbing heat from the outside air until it changes from a cold glass of water to a warm glass of water.

Now let’s look at how air conditioners use that same principle of heat transfer (on a much larger scale) to cool off your home.

How an AC transfers heat using refrigerant

To start, let’s think of that glass holding cold water as the copper coils in your AC system holding cold refrigerant.

Remember how that cold glass of water acted as a sponge to absorb the heat from the outside air?

Well that’s exactly what your AC’s refrigerant coils do: they use refrigerant (a special heat transfer fluid) to absorb the heat from the indoor air and release the heat outside.

Let’s take a closer look at this process:

Step 1: Cold refrigerant coils absorb heat from your home

Let’s start at your AC’s “indoor unit”.

First off, warm air from inside your home is pulled into your indoor unit via the blower. 

The warm air then passes over cold refrigerant coils that absorb the heat from the air.

Step 2: Cold air is blown back into your home

Once the air cools, it’s blown back into your house via your duct system and air vents.

Step 3: Refrigerant transfers heat to the outdoor unit

As more and more warm air passes over the refrigerant lines, more and more heat is absorbed. 

Eventually, the refrigerant absorbs so much heat that it turns into a gas and moves to your outdoor unit.

Step 4: Outdoor unit dumps heat outdoors

Once the refrigerant gas reaches the compressor in the outdoor unit, the gas is heated up to very high temperatures. The higher the temperature of the refrigerant, the faster the heat is transferred to the outdoor air.

Remember, heat naturally flows from a hot object (refrigerant) to a cooler object (outdoor air).

Step 5: Refrigerant travels back to indoor unit 

Once the refrigerant transfers its heat to the outdoor air, it travels to a small device inside your outdoor unit called the expansion device. This device turns the refrigerant back into a very cold liquid.

Once your refrigerant is a cold liquid again, it travels back to your indoor unit where it repeats the AC process over and over until your home reaches the desired temperature.

Have more air conditioning questions? Ask a Minnesota Tech

Now you have a good understanding of how your central air conditioner works.

Have specific questions about your AC system? Have an AC problem you can’t solve on your own?

Just contact the professionals at MSP. We’ll be over as soon as possible to find and solve the issue.


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Categories: Air Conditioning