What Is Air Conditioning?

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Updated May 18, 2023

If you are new to cooling technology, you may wonder what is an AC unit. Many of the best air conditioners, after all, don’t exactly advertise the internal design. So what is an AC unit, how do they work, what is SEER in an air conditioner, and what types are available? Aircons are systems that are used to cool the temperature of a living space. They do this by removing the heat and moisture from the space and blowing cool air back into the space. Keep reading to find out what is a window air conditioner and every other variant.


  • AC stands for air conditioning and AC units come in a wide variety of designs, each with different feature sets.
  • A portable air conditioner pulls in air from the outside and works to cool one room at a time.
  • Central air conditioners, also known as central air conditioning systems, cool the whole home at once, thanks to a compressor, a condenser, an outdoor unit, a heat pump, and various ducts.

Air Conditioners Defined

There is a lot to cover here, from answering what is a central AC system and beyond. First off, an air conditioner is an appliance that cools off an indoor space. They come in many designs if you are wondering what is a ventless air conditioner. The most common type is the central conditioning type, which is a single unit that cools off an entire building. This type of air conditioning equipment can be divided into two sections: an outdoor compressor and fan and an indoor evaporator coil. Some AC units cool air from the outside, and others, such as air handlers, transform indoor air if you look to compare swamp coolers vs air conditioners.

Insider Tip

No matter which type of AC you choose, be sure to replace or clean the air filters as indicated by the instructions.

So, yeah, an AC is anything that cools the air, if you want to know the definition of a package unit AC. The fan coil is a part of the air conditioning process that gets the output to the desired air temperature. It uses energy from air to cool the room and can be sized according to a structure’s air conditioner capacity. The fan coil is usually driven by an electric motor, which consumes energy accordingly to its air conditioner equipment power.

Air Conditioner Types

From window units and beyond, we’ve got you covered with all of the definitions you need, even if you wonder what is a mechanical air conditioner.

Window Units

These are the standard AC designs that hang out of the back of windows, working to cool one room at a time. They are budget-friendly, easy to use, and rather effective, despite having to be pulled out each winter. On that note, these appliances are not the lightest on the block, so prepare for some exercise.

The air conditioning components that make air conditioners work are a fan, condenser coils, compressor, and expansion valve. All of these air conditioner unit parts must be in working order for proper air flow to the unit and to cool off your home.

Portable Air Conditioners

These work similarly to window units, but they don’t hang out of windows. Rather, a vent attaches to the window to receive exterior air which leads to a duct that enters the air conditioner itself. As the name suggests, portable ACs are, well, portable. They often feature rollers to make it easy to move them from room to room with ease. Portable ACs are often more expensive than window units.

Central AC Units

If your entire house is being cooled via a single appliance it is a central AC unit. These ACs feature a large compressor and condenser located outside. Newly cooled air is pumped into the home via elaborate ductwork, though that is not always the case, as ductless designs do exist with modern central units. A/Cs, like central and window units, operate best when their air conditioner components are properly matched to the ambient temperature of their environment.

STAT: HVAC stands for Heating, Ventilation, and Air Conditioning. An HVAC unit is responsible for heating and cooling the air in your building, and provides ventilation to allow moisture to escape. (source)


How do air conditioners work?

Every air conditioner, from the outdoor unit to the indoor unit, works with similar principles. The various types of air conditioners use a condenser coil to get the indoor temperatures lower than the outdoor temperatures.

What to know about central AC maintenance?

Make sure to keep the outdoor unit free from debris and clean the filters associated with your window air conditioners and any affiliated indoor unit. Keep the evaporator coil clean and don’t lose the remote control, even if you use a portable unit.

Which air conditioner is right for you?

It depends on personal preference as to which air conditioner you choose. Window air conditioners are great for small apartments, as is a standard portable air conditioner, also called an indoor unit. There are many types of air conditioners and air conditioning units to choose from.

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