Warner Service has covered the basics of an HVAC system. However, with summer's arrival, many people ask about the anatomy of their window and central A/C units.

How does a window air conditioner work?


Photo courtesy of Green Living Ideas

Adjustable Louvers

This function helps direct the airflow in the direction of your choice. Most controls have at least up-and-down control of the air. Some units may have left and right louver controls as well. By adjusting these louvers, you can optimize the distribution of cool air throughout the room, ensuring comfort during hot days.


The blower is a crucial component that transfers warm air away from a desired location and returns cold air. It ensures that the air in your home remains at a comfortable temperature by circulating the cooled air efficiently.

Evaporator Coil

Located inside or near the air handler where the blower fan is, evaporator coils are made from copper, steel, or aluminum to help the coolant become gaseous, absorbing heat from the surrounding air. This process is vital for cooling the air, as it removes the heat from the indoor environment and provides a steady supply of cool air.


The compressor pressurizes the gas within the air conditioning system. This pressurization is essential for the refrigeration cycle, allowing the system to absorb heat from indoor air and release it outdoors.

Condenser Coil

The condenser coil is the area where heated gas becomes a liquid, releasing its heat to the outside air. This process is essential for maintaining the efficiency of the air conditioning unit, as it ensures that the absorbed heat is expelled from the system.

Control Panel

The control panel allows you to manage the air conditioning functions, from the fan speed and timers to auto random reset and other settings. It is the interface through which you can customize your cooling preferences.


The fan inside the window air conditioning unit's assembly is located between the condenser and the evaporator coil. Its double shaft fits the blower on one side and the condenser fan on the other side. This fan plays a vital role in maintaining the flow of air across the coils, ensuring efficient cooling.


Air filters prevent dust and grime from building up on air conditioner’s coils and improve indoor air quality by keeping dust out of your home. Regular maintenance of these filters is crucial for the efficiency and longevity of your A/C system.

Front Grill

The front grill provides a direction to the air that’s being distributed into your home. It also protects you from the mesh filter screen and mechanics of the window air conditioning unit. Proper maintenance of the grill ensures unobstructed airflow and optimal performance.


The partition separates the fan from the blower, allowing air to freely flow through the window air conditioning unit. This separation is vital for the efficient operation of the unit, as it prevents the mixing of warm air and cool air within the system.

Thermostat Sensor

The thermostat sensor detects temperatures and sends a resistance signal to the A/C control panel, allowing automatic adjustments to maintain the correct temperature in your home. This feature enhances comfort by ensuring consistent indoor temperatures.

How does a central air conditioner work?

It’s important to realize that window A/C units are smaller versions of central air conditioners, which means the latter still contains a compressor, evaporator and condenser coils, fan, thermostat sensor, air filter, and blower. You can see those parts in the diagram below:


Photo courtesy of Altitude Comfort

Air Duct

In a home’s distributed heating and cooling system, air flows through a system of air ducts that evenly distribute heat and air conditioning throughout your home. Proper insulation and maintenance of these ducts are essential for an energy-efficient system.

Condensation Drain Tube

This part removes condensation produced by the air conditioner's evaporator coil. It prevents the growth of algae and mold, elevated humidity, musty odors, and water damage inside your home. Regular cleaning of the drain tube ensures the proper functioning of the A/C system.

Floor Drain

A floor drain is a plumbing fixture installed in the floor of your home. It’s designed to remove any standing water near it, preventing water damage from a broken condensation drain tube. This feature is crucial for protecting your home from potential water-related issues.

Furnace Blower Switch

A furnace’s blower circulates air throughout your home, and the switch controls whether it’s on or off. This switch is an integral part of your heating and cooling systems, allowing for manual control when necessary.

Copper Tubes

Copper tubes keep the flowing air warm. Copper is used instead of aluminum because of its resistance to corrosion, high level of heat transfer, machinability, and consumption of less refrigerant. They’re also easier to repair, contributing to the overall durability and efficiency of the HVAC system.


The plenum is an enclosed chamber where a treated substance collects for distribution, as heated or conditioned air through a ventilation system. Proper design and maintenance of the plenum ensure efficient air distribution and system performance.

Room Thermostat

You can purchase a traditional, programmable, or smart thermostat for your home. These devices offer varying levels of control and automation, allowing you to manage your home’s temperature more efficiently and conveniently. You can find out more about both in A Quick Guide to Programmable Thermostats and More.

Shut Off Switch

This safety switch is simply designed to turn your unit on and off. It provides an essential safety feature, allowing for immediate shutdown of the system in case of emergencies.

Get the most out of your A/C system

Improving Indoor Air Quality

To improve indoor air quality, it is essential to maintain all components of your air conditioning system, including regular filter replacements and cleaning. Additionally, consider integrating an air purifier or ventilation system that introduces outdoor air to enhance overall air quality.

Energy Efficiency

Modern air conditioning units are designed to be energy efficient, reducing electricity consumption while maintaining optimal performance. Choosing an energy-efficient model can significantly lower your energy bills and environmental footprint.

Heat Pumps and HVAC Systems

A heat pump is an energy-efficient alternative to traditional air conditioning and heating systems. It works by transferring heat from one place to another, providing both heating and cooling capabilities. Integrating a heat pump into your HVAC system can improve energy efficiency and comfort in your home.

Understanding the basics of air conditioning systems, from window units to central air conditioners, is essential for maintaining a comfortable and energy-efficient home. Proper maintenance and regular updates to your system can improve indoor air quality, reduce energy consumption, and ensure reliable performance throughout the year. Whether you're cooling a single room or your entire home, knowing how your A/C unit works and how to keep it in top condition will help you stay cool and comfortable all summer long.

Now that you know how your A/C works, make sure you're scheduling regular, periodic maintenance to keep all the components running properly. Warner Service will service any parts of your window or central air conditioning - request a visit below to get started. 

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