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What are “Coils” & How Do They Work?

Do you know how your air conditioner works? If you don’t, there’s no need to panic or worry, in fact that makes you like most homeowners. Air conditioners aren’t exactly simple machines—they have a number of parts, both moving and not-moving, that all need to work correctly in unison in order for your system to not only function, but do so efficiently. Some of the most important parts among the rest are your air conditioner’s “coils.” You’ve probably heard about these parts, but to help you better understand what they do and why they need to be cared for, read on and we’ll give you a thorough explanation!


Your air conditioner actually has two different types of coils: condenser coils and evaporator coils. Each has their own extremely important function, and any problems with either one could cause your entire system to break down and stop working. An evaporator coil, sometimes called your “evaporator” core, is located inside your home, and it’s where the refrigerant absorbs heat from inside your home to carry it outside and release it. Just before refrigerant flows into this coil, the refrigerant passes through an “expansion chamber” which rapidly decreases the pressure the refrigerant gas is under, which rapidly cools it just before it passes through the cooling coils. The cold refrigerant is what absorbs the heat from the air that passes across the coils, which then cools the air that’s then sent into your home to keep your cool and comfortable.

However, there’s another half to the equation: your condenser coil. This coil is located outside in your large, square outdoor unit and essentially does the exact opposite of the evaporator coil: it takes the heat that’s absorbed from inside your home and releases it out into the atmosphere with the assistance of a large fan. Just before the refrigerant that absorbed the heat from the inside is passed through these coils and exposed to the rapid airflow, it’s sent through a compressor, which rapidly increases the pressure it’s under, causing it to become blistering hot extremely quickly. When the hot refrigerant passes through your condenser coil, the large fan pulls air across it in order to remove as much heat as possible while still keeping the refrigerant under high pressure. This is why the air coming out of your outside unit often feels warm or even hot. Once the refrigerant moves back to the expansion chamber, the lost heat allows the refrigerant to quickly cool itself again and start the cycle over.


The coil’s refrigerant lines are often constructed from a metal that’s extremely proficient at heat transfer, often copper or aluminum, and is lined with other thin pieces of metal called “blades” that direct more air past the refrigerant line in order to maximize its effect. There’s a reason for this: air conditioners depend on rapid and efficient heat transfer in both the indoor and outdoor units in order to maximize energy use.

Coils are also often designed to maximize the coil’s exposure to untreated air in order encourage as much air as possible. Many people hear the term “coil” and think of a shape that’s kind of like a slinky or a spring, like they might find in their mattress, but this isn’t a shape that’s conducive to an abundance of heat transfer. In the case of your air conditioner, a coil is usually a piece of metal that weaves back and forth in a zig-zagging motion that’s designed to allow as much airflow as possible over the line.


As you might expect, with so much air passing over your coils, it’s only natural that they’ll eventually become dusty and need cleaning with repeated use. But is this all that important? Well, to put it simply, yes, it’s extremely important. Even a thin layer of dust on a coil functions like a blanket, preventing the much-needed heat transfer that keeps your home cool in the summer. A dirty evaporator coil can’t effectively cool the air in your home, leading to longer run times and wasted energy. A dirty condenser coil is going to retain more heat, preventing the heat loss needed in order to allow the refrigerant to get as cold as you need it to in the expansion chamber. Less heat loss outside means warmer air coming from your air conditioner, and thus higher energy bills and wear and tear levels on your system.

Cleaning your coils is something you should do every single year, ideally just before the start of the warm summer season that will have you running your air conditioner for hours at a time. Clean coils mean a more efficient system that uses less energy and keeps you more comfortable thus making this important maintenance service a no-brainer for homeowners. Coil cleaning is a service that’s provided as a part of our maintenance services, along with a full inspection of your electrical connections, lubrication of moving parts, and much more.

To schedule a maintenance service for your air conditioner, speak with the Los Angeles air conditioning experts at JW Heating & Air today! Contact us at (888) 523-7445 to schedule a maintenance service appointment for your home.