ac condenser

How Does My Central Air Conditioner Work, and What Do the Major Parts Do?

Major components in a central air conditioning system must operate together in ready condition to produce cool air. Some of these components include the evaporator, condenser, compressor, filter, and thermostat. AC equipment requires periodic maintenance and tune-ups to make it run efficiently.

Below, we’ll explain how your central air conditioning system works and describe what it’s key parts are and what they do.


AC systems remove heat and humidity from indoor air by transferring it outside and replacing it with cold air. A refrigerant that can change into gas to liquid then back to gas makes the process possible. The refrigerant plays a key role in absorbing heat from your indoor air to make that air cooler. The heat the refrigerant picks up gets released outdoors, and from there, the refrigerant cycles back indoors.


While the thermostat and fan (the part of your AC that blows the air) need regular inspection, the components that control the refrigerant should be tuned up annually to preserve your system’s efficiency. When it comes to the air filter, most will generally last up to 90 days, but always check the manufacturer’s instructions.

Below are some of your air conditioner’s most crucial components:


This is a term for the indoor unit. The evaporator contains a cooling coil with refrigerant that removes heat and humidity from your indoor air. An expansion valve allows the refrigerant to turn into a cold liquid flowing through the coil in the evaporator. An annual tuneup keeps the coil clean and working efficiently.

You may help delay repairs or replacement of your evaporator coil by changing the filter as often as the manufacturer recommends. Dirty filters let particles pass through, and they accumulate on the coil. A test that may surprise you lets you check the ineffectiveness of some inexpensive filters. If you shake black pepper on it only to see it pass right through, then you know the filter cannot protect your evaporator coil.


The condenser is another word for your AC’s outdoor unit. Hot, gaseous refrigerant, carrying the heat from your indoor air, leaves the evaporator and goes to the condenser, where the heat can be released. As the heat transfers to the great outdoors, the refrigerant condenses back into liquid form.

The fan that you may see or hear cools a coil where this process occurs. Exposure to the elements can allow dirt and debris to accumulate on the coil. During professional spring AC maintenance, your technician should take time to clean this coil to keep it running at peak efficiency.


The compressor helps your AC’s refrigerant condense from a gas to liquid and move through your AC system. As the compressor moves gas refrigerant from the evaporator to the condenser (indoors to outdoors), it applies pressure that reduces its volume. The critically important process provides one of the essential functions of central air conditioning.


Preventative maintenance keeps system components clean and efficient, the key to avoiding equipment failure. Regular tuneups can detect potential problems and prevent the need for expensive repairs. When equipment failure or breakdowns occur, we can remedy any situation.

Choosing the Highest Quality of Service

At Tom's Mechanical, Inc., our reputation for excellence rests on our 60 years of HVAC solutions for Arlington and Dallas-Fort Worth. We can handle any problem that may occur with your central air conditioning system, and we offer 24-hour service for emergencies. Call us at (972) 388-3669 for expert care of your AC equipment.