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parts of an air conditioner

What Are the Different Parts of an Air Conditioner?

If your air conditioner isn’t working for any reason, trust the professionals of Green Energy Mechanical Inc. to diagnose and repair the issue. Call (781) 236-3421 for an appointment. 

Chances are when you want to cool down on a hot day, you aren’t thinking about the parts of an air conditioner. You probably don’t realize that the cool, comfortable air is because of many components working together to remove heat and humidity from the room. But if any of them fail, it doesn’t take long for the entire system to stop working, leaving you uncomfortable.

Having a basic understanding of the primary components of an air conditioner can help you troubleshoot issues and know when to call a technician for help. As the leaders in professional AC installation in Canton, MA, we are experts in all things air conditioning. Here we highlight the major system parts, what they do, and how they all work together. 

The Four Primary Components of an Air Conditioner

The four primary parts of an air conditioner—the evaporator coils, compressor, condenser coils, and expansion valve— work together to produce cool air. These are the workhorse parts of the unit, and a breakdown in any one of them can cause a total system failure.

Evaporator Coils

Found in the indoor unit of a central air system or the air handler in a ductless mini-split air conditioner, the evaporator coils are copper, steel, or aluminum and contain cooled refrigerant. The HVAC unit pulls air in and over the coils to remove heat, and the fans behind the coils blow the cooled air back into your home. 


Located in the outdoor unit of any air conditioner, the compressor is perhaps the most important part of the entire system. The compressor compresses the refrigerant from a warm vapor into a hot liquid, which then cools and expands as it moves through the evaporator coils and removes heat from the air.

Condenser Coils 

As the compressor turns warm vapor into hot liquid, it produces heat. The condenser coils remove that heat so a blower can push it outdoors. 

Expansion Valve 

Liquid refrigerant cannot remove heat from the air; it must be in gaseous form to absorb heat. The expansion valve connects the condenser and the evaporator to convert the liquid into gas. When the liquid refrigerant from the condenser enters the valve, it’s exposed to a sudden drop in pressure, causing it to cool rapidly and become a gas before entering the evaporator coils to start the cooling process again.

The Basic Air Conditioning Process 

The major parts of an air conditioner work together seamlessly to produce cool air. 

The cycle begins with the compressor producing hot liquid refrigerant, then sending it to the condenser coils. A large fan cools the refrigerant, which then travels through the expansion valve, where it becomes a cold gas. That gas enters the evaporator coils and makes them cold, and when the unit pulls warm air in from your home, the cold coils remove the heat, and a fan blows the cooled air back into your home and lowers the temperature.

This process occurs continuously as long as you have the air conditioner running. The unit also contains a few additional components that make it possible.

Additional Elements of an Air Conditioner

Some of the other important air conditioner components include the following:

Air Filter

Air filters keep dust and other contaminants from accumulating on mechanical components. They also help improve indoor air quality.


Refrigerant is the substance that actually cools the air. Older air conditioners used R-22 or freon for cooling, but today most units contain R-410A, a more environmentally friendly refrigerant. 


Air conditioners have several fans to move the air around within the unit and push heat outside, preventing the mechanical components from overheating. 


The thermostat communicates your desired temperature to the air conditioning unit, so it turns on and off as needed. Thermostats have temperature and humidity sensors to automatically control indoor cooling. 

Get Help with Air Conditioning Problems from Green Energy Mechanical Inc. 

If you notice problems with any parts of an air conditioner, like unusual sounds or smells, reduced performance, leaks, or it stops working altogether, call the experts of Green Energy Mechanical Inc. for help. Home and business owners in the Canton, MA, area rely on us for prompt, efficient, and reliable AC maintenance. Call us at (781) 236-3421 to schedule an appointment with one of our certified technicians today. 

Author Bio:

Jonathan Neves

Worked in the HVAC industry since he was 17. He started as an HVAC service technician for commercial buildings and eventually came into the residential market because of his love of working with people. He believes that what really sets Green Energy Mechanical apart is how long they stand behind their work and how compassionate his employees are for their clients.


My furnace was not working this morning. I called Green Energy and within a few hours Terry was here and quickly took care of the problem. Terry has been here before and is very professional and friendly.
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Very professional operation. Great technicians. Follow COVID protocol. Leave your house and property very clear with no trace that work had been done.
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Quinn was really nice, professional, and answered all my questions in a clear and easy manner. The woman I spoke with on the phone was also very kind, so I will definitely use this company again.
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Green Energy Mechanical is a pleasure to work. We had both air conditioning and heating installed. During both jobs, GEM was thorough and professional from start to finish.
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I could not be more pleased with the service provided. We have upgraded our water heater to a tank less. We are also getting our heat and ac installed by them. They care for your home like you would
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