How to Clean Your AC’s Evaporator Coils

Having a properly working air conditioner has become an essential component of most of our lives, which means preventative maintenance performed on your equipment on a regular basis. When maintaining your equipment, something easy to overlook is the evaporator coil, which will need to be occasionally cleaned to keep up your unit’s effectiveness and efficiency levels. 

But not everyone knows how to clean evaporator coil systems, and it’s often something that’s better left to technicians. But if you’d like to learn how to do it yourself, continue reading this article, and we will explain the whole process. You can also check out this article covering other ways to help make your unit more efficient.

What is an evaporator coil?

First, let’s start with what an evaporator coil is. The evaporator coil will be located before or after your blower fan, in the indoor unit, unless you have a package unit. The evaporators’ job is to allow the refrigerant to flow through it while it soaks up the heat from the air entering the unit through your return. As the air passes through the coil, the refrigerant takes the heat outside and cools the area indoors.

When you open the door of your air handler or the front cover of your coil cabinet, if it is a gas system, you will see the evaporator coil. Evaporators can come in many sizes and shapes, depending on your unit’s size and tonnage. It could be just a slab or in the form of a triangle, as these are the most common shapes, but it could be in the shape of an N or M. 

It will be easy to determine where it is because your copper lines or line set will be running directly to it. You can read more about the different components involved in your HVAC system, here is an excellent article covering all the different HVAC components.

Why is it essential that your evaporator is clean?

Since the air must pass through the coil to cool down the air, the coil must be clean enough for the air to get through. If the air cannot pass through the coil, your home will not cool down correctly. If the air is unable to move effectively, then the refrigerant in the coil will be unable to gather any heat out of the air, and the coil will begin to freeze.

It is normal for your coil to have a small amount of buildup. However, if you have not changed your filter regularly or used highly cheap filters, it can lead to a large amount of buildup of dirt and debris.

Even if there is only a small amount of dirt on the coil, it is still essential to clean the coil regularly to ensure your air’s cleanliness and prevent any airflow restriction.

What will you need to clean your evaporator coil?

It may be best if you could inspect your coil before putting together a list of things that you will need. Depending on the level of dirt accumulated in your coil, you may need this entire list of just a couple of things.

  • Nut driver/socket: You will use this to gain entrance to your coil
  • Compressed air: This may come in handy if you have an air compressor with a blowgun. You can use it to blow air through the coil and break up some dirt and grime.
  • Firm-bristle brush: This will be used to clean up most of the buildup on the coils.
  • Coil cleaner: For heavily soiled coils.
  • Water sprayer/container of water: To rinse the coil

How to clean evaporator coil setups?

The first step to cleaning an evaporator coil is to shut the power off to your unit. Once the power is off, you will want to find out which cover your coil is behind and take it off. You will need either a ¼ or 5/16 socket driver for this part. Once the cover is taken off, you should be looking at your evaporator coil. 

Depending on your coil’s shape and how the air flows in orientation to the profile, you may need to pull the coil out to access it. It is especially important that you are careful with this part. You should be able to pull the coil out enough to reach the entirety of the dirty side, but if it does not want to come out, you may check for a screw or clip at the coil’s base. 

Make sure that you are very gentle with the copper tubing going to the coil. This tubing can bend easily and cause catastrophic failures if it is crimped and unable to flow the refrigerant properly. Here are some options of how to clean evaporator coil setups based on the level of buildup on them.

Lightly soiled: What if you need to know how to clean AC evaporator coils that are only lightly soiled? This will be the easiest one to do, and it will show that your HVAC system has had regular maintenance performed on it. If your coil is only lightly soiled, you may try and use the compressed air first to see if you can blow out any loose dirt from the coil. 

Once you are done with that, you can spray it with your garden sprayer and attempt to get some more of the stubborn dirt between the coil fins. There will be a plastic pan underneath your coil that will connect to a drain line. The excess water should flow down this drain without damaging your unit, floor, or anything else as you rinse your coil off.

Medium soiled: Looking to know how to clean evaporator coils on AC units when they’re medium soiled? First, you will want to take your brush and brush the coil off. Make sure that you brush the coil in the same direction as the fins only. If you brush to the side, you can cause extreme damage to your coil.

Next, you will break out the coil cleaner. Read the instructions and apply the coil cleaner appropriately. Each coil cleaner may have a different process to work the most effectively. The coil cleaner will foam up and pull more of the buildup out from between the coils. 

If your coil cleaner’s instructions ask you to rinse it off when you are done, you can use your garden sprayer to do it efficiently. A garden sprayer is an excellent option because it has enough pressure to help push the buildup out of the coil but not enough to damage the coil’s aluminum fins.

Heavy buildup: How to clean evaporator coils in HVAC units with heavy buildup? This will be done at your discretion, as this may require a professional depending on the level of buildup. 

If you believe it is something you can tackle, brush the dirt off, blow it out with compressed air, and spray it with the garden sprayer. This may take several cycles, but once you have gotten it close to clean, you can begin to use your coil cleaner.

In the worst-case scenario, you might need to unhook the evaporator coil entirely and take it elsewhere to clean it properly. If the buildup is too extreme and you don’t want to risk potential damage, go ahead and schedule an appointment with your trusted AC technician.

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