How Does a Window Air Conditioner Work?

During the hot summer days, there’s nothing more refreshing than stepping into a cool, air-conditioned room. Have you ever wondered about the physics of window air conditioners that make this possible?

This guide will explore how a window air conditioner works, its history, benefits, downsides, and much more.

How Does a Window Air Conditioner Work?

The basic components of a window air conditioner include a compressor, a hot coil (outdoor coil), a cold coil (indoor coil), two fans, and a control mechanism.

The refrigeration cycle starts when the compressor pumps the cold refrigerant to the condenser coil (hot coil). Here, the refrigerant releases heat to the external atmosphere, cools down, and becomes a high-pressure liquid.

The refrigerant then moves to the evaporator coil (cold coil), where it absorbs heat from the indoor space, leaving the room cooler.

The fans, one located by the hot coil and the other by the cold coil, aid in the flow of air to speed up the cooling process.

This hot air cycle and cold air cycle continue until the desired temperature is achieved, controlled by a remote control or a thermostat on the unit.

Who Invented the Window Air Conditioner?

The window air conditioner, a true marvel of modern technology, was invented by H.H. Schultz and J.Q. Sherman in 1931. However, these units were expensive and were not as common in households until the post-World War II economic boom.

How Have Window Air Conditioners Evolved Throughout History?

The earliest window air conditioning units were large, costly, and inefficient. Over the years, technological advancements have led to smaller, more efficient, and affordable models.

The energy efficiency of window AC units has improved significantly, with many models now boasting Energy Star certifications.

In addition, the introduction of digital controls, remote control access, and programmable thermostats have enhanced user convenience and precision in temperature control.

What are the Parts and Functions of Window Air Conditioners?

The essential parts of a window air conditioner include:

  1. Air Inlet Grille: This is where the indoor air enters the AC unit. An air filter traps unwanted particles such as dust particles to ensure the circulated air is clean.
  2. Evaporator Coil: This indoor coil absorbs heat from the room, cooling down the air.
  3. Fan Blower: It circulates the cool air back into the room.
  4. Compressor and Condenser Coil: The compressor pressurizes the refrigerant and sends it to the condenser coil, where it releases the absorbed heat to the outside.
  5. Propeller Fan: This fan aids in dissipating the heat to the outside atmosphere.
  6. Controls: These may be manual or digital controls that allow you to adjust temperature settings, fan speed, and other options.

Are Window Air Conditioners Any Good?

Yes, window air conditioners are an excellent solution for cooling single rooms or small spaces. They’re energy-efficient, easy to install in double-hung windows or casement windows, and are usually more affordable than central air conditioning units.

What are The Benefits of a Window Air Conditioner?

Cost-effective: Window ACs are relatively inexpensive compared to central air conditioning or multi-story buildings’ cooling systems. They also consume less energy, reducing your energy bills.

Ease of installation: Most window air conditioners are designed for double-hung windows, and with a little DIY knowledge, you can install one yourself.

Space-saving: Since they’re installed in a window, they don’t occupy floor space like portable air conditioners.

Targeted cooling: They are perfect for cooling individual rooms or specific square footage.

What are the Downsides of a Window Air Conditioner?

Limited to one room: Window AC units are typically designed to cool one room. You might need multiple units to cool an entire home.

Window use: Once installed, the window can’t be used for ventilation or view.

Noise: While modern window air conditioners have become quieter, they can still produce some level of noise.

Does a Window AC Take Air From the Outside?

No, window air conditioners do not take in air from the outside. They cool the indoor air by pulling it into the unit, passing it over the cold evaporator coil, and then returning the cooled air into the room.

How Long Should you Leave a Window Air Conditioner On?

You can leave a window air conditioner on as long as needed to maintain the desired temperature in the room. However, for energy efficiency and unit longevity, it is recommended to turn off the AC if you’re away from home for an extended period.

Do You Have to Empty a Window Air Conditioner?

Unlike portable air conditioners, window AC units do not need to be emptied. They are designed to evaporate the condensation and drain it outside through a drain hole in the unit.

How do Window Air Conditioners Stay in Place?

Window air conditioners are secured in place using a mounting kit that includes brackets, screws, and sometimes support platforms. They are designed to fit snugly within the window frame for secure installation.


Window air conditioners are a reliable, cost-effective, and energy-efficient way to cool individual rooms or small spaces.

Understanding how a window air conditioner works, its history, and pros and cons will allow you to make an informed decision about whether it’s the right choice for your cooling needs.

Be sure to check online reviews and consult with an HVAC professional if you need more personalized advice.

About Roy Cohen

Roy Cohen has a burning passion for heating, cooling, and ventilation. He aims to help you save money on expensive repairs and bring you the best HVAC products. He has years of experience behind him in HVAC repair and garage maintenance.

You can find Roy at his LinkedIn or his email: [email protected]

Related Posts