How Does a Window Air Conditioner Work?

Window AC is a wonderful technology that is often underappreciated. Like many people who have seen one, you must be wondering how window air conditioners work? What is the sorcery behind it? Can it keep your room cool during the summer? What are the advantages and disadvantages? Perhaps more importantly, which type of AC is the right type for my home? Sit back, relax, and we will answer everything in detail.
Short answer
Work just like any air conditioner; on a window.


What Is A Window Air Conditioner?

A window air conditioner is the least complicated type of AC that uses two air cycles (room air cycle & hot air cycle). It consists of all components inside one casing, including a thermostat, a fan/ blower, compressor, evaporator coil (cold), condenser coil (hot), and refrigerant tubing.

A window air conditioner is installed in a window and requires plugging into a standard electrical wall outlet for operation. It is a standalone unit that is independent of a home HVAC system. Because of its smaller body, you can conveniently move it from window to window cooling.

How Do Window Air Conditioners Work?

How window air conditioners work is the same as every other air conditioning system. It uses refrigeration technology to remove heat and humidity while releasing cool air back into the room. When the room temperature rises higher than your desired temperature, it triggers the built-in thermostat to turn on the fan/ blower. The fan will blow the hot room air inside the unit, passing through the air filter that traps dust, hair, and dirt particles and prevents them from clogging the evaporator coil. The protected evaporator coils will cool the refrigerant to absorb the heat. Cool air will be dispersed into the room, effectively bringing down the room temperature and humidity. The refrigerant then flows to the outside window unit for compression and pressurization. The compressor will convert the cold refrigerant into a vapor, and the condenser coil will dispel the hot air outside. The refrigerant cold and heat cycle will repeat until the AC blower is turned off.

How To Pick The Right Window Air Conditioner For Your Home?

Like all AC, windows air conditioners come in all shapes and sizes with different BTU. Window air conditioners typically have a cooling capacity from 5,000 to 12,500 British thermal units (BTU/ hr). First and foremost, make sure the window AC will fit on the windows you intend to install. Next, measure the room size, including the ceiling height that you intend to place the windows air conditioner. The window AC unit must have enough cooling capacity to cool the room. If the AC is too small, it will take a long time to cool the room or fail to do so. If the AC is too big, it will waste much energy as it cools the room too quickly. You will feel sticky as the humidity has not been adequately ventilated.

BTU is the abbreviation for British Thermal Unit. A metric measurement shows how much energy an air conditioner uses to remove heat within an hour. It can help you determine the sizes of air conditioners needed for your home. As a rule of thumb, a window air conditioner needs 20 BTU to cool each square foot of space. Get the room size by multiplying its width, length, and ceiling height. Multiply the room size by 20 BTU to get the cooling capacity needed for the right window air conditioner. Additionally, Energy Star recommends making the following adjustment:

  • The room is dimmed/ heavily shaded – reduce cooling capacity by 10%.
  • The room is bright/ very sunny – Increase cooling capacity by 10%.
  • More than two people in the room – Add 600 BTU for each additional person.
  • The kitchen – Increase cooling capacity by 14,000 BTU.

Final Thoughts

We hope by now you understand that window air conditioners work just like every other AC unit. The only major difference is that a window air conditioner can be mounted on a window. Your next step is to ensure the window AC is in tip-top condition, so there is no disruption in the heating and cooling process. Periodically maintain the air conditioner and clean the air filter every few weeks to remove the captured particles. Hire trained service technicians if any fixing is required.

Max Fernandez