Evaporator Coil Cleaning: How to clean AC coils without removal
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Evaporator Coil Cleaning: How To Clean Your AC’s Evaporator Coil

How Often Should an Evaporator Coil be Cleaned?

Proper HVAC air conditioner and furnace system maintenance is crucial to maintaining its longevity and lowering your utility bills. While you may regularly perform maintenance on your outdoor unit, your indoor unit will also need attention, primarily your evaporator coil. Lets learn more about evaporator coil cleaning and how to clean AC coils.

To keep your air conditioning system operating efficiently, it will need to be able to transfer heat from indoors to outdoors effectively. When the evaporator coil becomes coated with debris, dust, and grime, the heat transfer process will be affected, and the energy efficiency of your system will wane.

Your evaporator coils will need to be cleaned at least once per year to maintain efficiency, and this will likely be part of your regular maintenance visit. If you don’t have regular maintenance visits, you will need to have your air conditioner evaporator coil system serviced by a technician or yourself before the beginning of the cold season.

How Much Does it Cost to Have a Coil Cleaned?

To have your evaporator coils professionally cleaned, you can expect to pay anywhere between $100 to $400 if it is a stand-alone service. If you have an HVAC service contract, cleaning the coils will likely be part of the annual or bi-annual service. These contracts can run between $150 and $300 per year, depending on your system and the type of services provided under the contract.

When to Call a Professional

Properly maintaining your evaporator coils is a crucial part of maintaining your system. While the process can be DIY and you can learn how to clean AC coils, you may benefit from having a regular HVAC maintenance contract that will include at least one evaporator coil cleaning per year. If you are between services and notice a buildup of debris on your coils or reduced airflow that could be the result of dirty coils, you should contact a professional immediately for cleaning and inspection.

Types of Evaporator Coils 

Different types of evaporator coils can be part of the indoor component of your central air conditioner. The type of coil paired with your system will depend on the type of system and where the coils will be placed.

Vertical Evaporator Coils

You will typically find vertical AC evaporator coils paired with a vertical air conditioning system. These air conditioners use an up-flow/downflow, which means that the air will move either upward or downward when it moves through the coil. The coils in these systems will condense the heat from pre-processed air into water. The coil will then direct the water toward the drain and lower the humidity in the home.


Cased evaporator coils will be positioned horizontally and have a metal casing surrounding them. These types of coils are most commonly found in a residential system and serve the same purpose as vertical ones, with a different shape and size.


Uncased coils can be placed to become either vertical or horizontal and will not have a protective case around them. The lack of a casing makes them easier to customize, which makes them perfect for more unique air conditioners that require possible reconfiguration of the coil shape, especially when the coil needs to fit in a smaller space.

Horizontal Evaporator Coils

Horizontal AC evaporator coils are used on AC and furnace systems as well. These are installed in the horizontal position or laying on its side. 

Symptoms of a Dirty Evaporator Coil

Even if you have regular cleaning performed on your evaporator coils, knowing the signs of a dirty one and how to clean AC coils is essential in case you run into problems between maintenance visits. A dirty evaporator coil can significantly affect the efficiency and function of your system, which means any time it is overly dirty, the issue needs to be addressed. Some signs that your evaporator coil needs cleaning include the following:

Reduced Cooling Capacity

When an evaporator coil is dirty, one of the main signs is a reduced cooling capacity. This is because the heat transfer process has been lessened, and the coil can not as effectively cool the air. So, if you notice that the air coming out of your vents is not as cool as it was, it could be a sign your coils need cleaning.

The System Runs Longer

Another indication that your evaporator coils may be dirty is if your AC system is running for longer cycles. Dirty coils can inhibit the heat transfer process, and the system may take longer to cool the air effectively. Because of this, your system will have to work harder and longer to get to the right temperature than it would if your coils were clean and working properly.

Your Coils Have Frost

If you notice your evaporator coil is frosting over, it could mean the coil is dirty enough to cause a potential breakdown. Frosting means condensation is forming on the dirt, and the buildup of the frost will eventually stop the heat transfer process entirely and cause the system to stop cooling.

Other Causes of Blocked Air in Your AC Unit

Blocked air in your air conditioning system can be caused by other problems besides a dirty evaporator coil. It is important to be aware of these potential problems to better troubleshoot your HVAC system and determine which repairs are needed. Other blocked air causes include:

  • Clogged Air Filters: If your air filters are clogged with dirt and debris, they can mimic the same problems as a blocked coil. If you notice a reduced cooling capacity, always check your air filter first, and be sure to check your filter regularly throughout each season.
  • Misplaced Air Filter: In some systems, it is possible to put your air filter in the wrong way, with the arrow pointing against the airflow direction. When this happens, the materials in the air filter can be torn out and caught against the coil, blocking it and causing clogging.
  • Air Leaks: If you have openings in your air ducts that you don’t notice or other air leaks along your system, the airflow will be impeded, and air delivery can be lessened. The results will be similar to what occurs with a dirty evaporator coil.
  • Damaged Fins: Damaged air conditioner coil fins in either the evaporator coil or the condensing coil can cause a blockage of airflow, but this will only cause loss of function and coil icing if the damage is severe.
  • Dirty Blower Fan: If the blower fan in your air handler becomes caked with dirt, debris, and grime, the airflow pushing across the evaporator coil will be lessened. When the airflow is reduced, it can potentially lead to coil icing and problems with your system’s function.

Evaporator Coil Cleaning Without Removal

You can clean your evaporator coil in a few different ways, but if you are looking for the safest DIY option, you will want to do it without removal. This process only requires basic HVAC knowledge and skills and has less chance of resulting in system damage. To begin cleaning, you first must gain access to the coils.

  • Turn off the power to your air conditioning system by removing it from the power source so that you don’t accidentally turn it on. This is for safety and should be the first step in the process.
  • Locate the panel to expose the evaporator coil. Check your manual to familiarize yourself with the evaporator coil how to clean AC coils and how to properly locate the access panel.
  • Remove the access panel by undoing the fasteners or unscrewing it, making sure to secure the screws and fasteners so that they don’t get lost or fall into the system. Otherwise, you may be fumbling to get the panel back on when the time comes.

Compressed Air

Use a compressed air container to push off dust and loosen and remove built-up debris. If it is dirty and is not coming off as quickly, you can get closer to the coils with the nozzle or use a 90-degree approach to remove them.


If the compressed air is still not working well on stickier grime or dirt, you may need to mix warm water and mild detergent in a sprayer. Use the solution and a soft-bristled brush to gently clean away any buildup. If you have to use soap and water, you will want to ensure that your evaporator coils are completely dry before using them.

How Long Before I Can Turn my AC Back On?

Once you have cleaned your evaporator coils, you may need to allow your system to dry before turning the AC back on. Leave the access panel off and wait 30 to 60 minutes before turning the system back on.

Evaporator Coil Cleaning With Removal 

If you have a significant buildup on your evaporator coils or stubborn grime that won’t come off, you may need to get more in-depth with cleaning your evaporator coil. If you are not as experienced with HVAC, you will need to fully familiarize yourself wth how to clean AC coils or you may want to call in a technician. A professional HVAC technician will know exactly how to clean AC coils and might be a better option. But if you want to attempt to do it yourself, below is a step-by-step process.

  1. Turn the power off on your system on the electrical panel to ensure your safety during the cleaning.
  2. Find your evaporator coils. Most often, the evaporator coils will be found on the supply side of your indoor air conditioning system beneath an access door. You can open the door by removing the screws or fasteners.
  3. Thoroughly inspect the coils. Your coil assembly should be in the shape of an “A,” You will want to inspect both sides of the coil, but the dirtiest side will most likely be the inner section.
  4. Use a soft bristle nylon brush to clean the aluminum fins gently. Make sure you clean in the long direction of the fins, starting at the top of each one and moving downward. Make sure to use gentle smooth motions, as the fins can become easily damaged. Use a small handheld vacuum to suck up the debris as it’s removed.
  5. If any fins on the evaporator coil have been bent or flattened, they should be fixed. Use a fin comb to straighten the fins back in place gently.
  6. Spray the inside of the evaporator coil with a foam coil cleaner. These cleaners can be found at your local hardware store and should have instructions for proper and safe use. Spray a liberal amount of the cleaning, making sure to coat the entirety of the coil.
  7. The cleaner will need about five minutes to work and then should be thoroughly rinsed off with clean water. To avoid applying too much water, use a spray bottle and apply a little to each section until the cleaner is removed. You can use a shop vac in wet mode to suck up the excess water.
  8. Let the evaporator coils dry for about an hour with the access door open. Once completely dry, you can replace the access door, affixing it in place with the proper screws and fasteners. Then close the door to the system and turn the system back on at the electric box.

Using Commercial Cleaners

Homeowners should exercise caution when using commercial coil cleaners and understand the type of cleaner they need for their system and how to use it safely. Most cleaners will be safe to use on either aluminum or copper coils, but you should always check your packaging. If you have copper coils, cleaners that are too acidic can cause corrosion.

Commercial cleaners work through the use of expanding foam that is designed to fill in the air in-between the coils as it expands. Once coated, the foam will work to lift off the dirt and grime in between the fins, which can be hard to get to with a brush. The process takes between five and ten minutes, but you should always check the specific instructions with the cleaner for the proper time.

Superior Home Supplies Can Help You With Your Evaporator Maintenance and Repair

At Superior Home Supplies, we understand how important a properly functioning evaporator coil is to the function of your air conditioning system. We offer all the supplies you need for evaporator coil maintenance and replacement of air conditioner evaporator coils if your system needs them and provide support on how to clean AC coils. No matter your HVAC needs, we have what you are looking for. Contact us today or check out our HVAC coil inventory.


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