The anatomy of an HVAC unit


You might not give HVAC anatomy much thought until your air conditioner develops an issue and you wonder why. Learning about A/C components can help you determine where the problem might lie and how to avoid it in the future. If your A/C is like many, chances are high that you have what is often called a split-system central air conditioner. Regardless of the type, HVAC anatomy is similar and is described below.



Indoors you’ll find important air conditioning components such the evaporator coils and the blower. The blower pulls your home’s indoor air over the evaporator coils, which are filled with refrigerant. The refrigerant enters as a liquid and then turns into vapor.

What happens within the evaporator is a process called heat exchange. It helps to note that heat is always attracted to cold and so the heat from the air is attracted to the refrigerant. As the warmer indoor air flows over the cool evaporator coils, much of the heat from the air is removed. This cooler air is then circulated into your home through the air ducts. The refrigerant, meanwhile, returns to the compressor, which is housed in the outdoor part of your air conditioning system.



The outdoor unit houses the compressor, the condenser coils and an exhaust fan. As refrigerant vapor moves into the compressor, it undergoes intense pressure and heats up even more. Next, it moves to the condenser coils where it is released from pressure and expands. There it loses heat and reverts to its liquid form. The exhaust fan blows over the condenser coils to push this heat out of the unit into the outdoor air. This is why, if the air conditioner is cycling, you can feel hot air being blown out of the outdoor section of the A/C system.



In HVAC anatomy, refrigerant can be seen as the lifeblood. Without it, your air conditioner cannot supply cool air to the home no matter how hard the other components work. Refrigerant moves between the indoor and outdoor A/C components by way of refrigerant lines, which are typically made of copper.

There are different types of refrigerant, but they all perform the same kind of function. If your A/C is over a decade old, it might use an older kind of refrigerant that is no longer allowed in newly manufactured air conditioners due to the impact on the ozone. This is R-22 refrigerant. Old air conditioners can still be recharged, if necessary, but it can get expensive. This is one of the many reasons that you might consider simply replacing an old air conditioning system when it needs frequent repairs.

In addition, note that refrigerant gets recycled through the system. If your air conditioner needs a refrigerant charge, it means there is a leak somewhere that needs to be fixed.


The Filter

Your air conditioner’s filter might not seem like it is important, but it has a very important job. A good, clean filter keeps harmful dust particles out of sensitive components and keeps ductwork and your home’s indoor air cleaner. One of the most common mistakes people make is leaving dirty air filters in the unit without changing them.

Soiled filters block airflow to the air conditioner. This can lead to many problems, such as dirty coils, a burned out fan motor, and polluted indoor air.

Air conditioners work differently than some people think they do, and this means a little knowledge of what different parts do can be helpful as well as interesting. By keeping in mind how things work together, you have a better idea why it is important to keep all parts in good shape. For more information or to schedule HVAC maintenance, please contact us.


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