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Home and Garden
Heating and Cooling
Air Conditioning
How to Clean an Evaporator Coil Download Article Co-authored by Walter Brant
Last Updated: March 10, 2025
Download Article
Preparing the Air Handling Unit
|
Using a Pump Sprayer and Brush
|
Cleaning with Mild Detergents and Water
|
Spraying with Commercial Cleaners
|
Video
|
Expert Q&A
|Show more|Show less X
This article was co-authored by Walter Brant. Walter Brant is a wikiHow community member and contributor who has been repairing and restoring houses with over 30 years of experience. He works with homeowners to make a wide variety of improvements to make their homes more comfortable and liveable. This article has been viewed 125,973 times.
Air blowing across the coils in your air conditioning system can cause dust and other debris to stick to the coils. Systems with dirty coils use more energy than those with clean coils and cool spaces less efficiently. By annually cleaning the evaporator coils of air handling units before the cooling season starts, you can increase your A/C system's cooling efficiency and overall life expectancy! Note that regardless of which cleaning method you choose, you will need to start with preparing the air handling unit, and end with restoring power to the air handler and turning on the system.
Steps
Method 1 Method 1 of 4:
Preparing the Air Handling Unit
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1 Turn the A/C system off and shut off the electricity to the air handler. Air handler units are located indoors, usually in a closet or attic. Turn off power to the air handler by flipping the toggle switch near the air handler (the switch looks like a light switch). If you cannot locate the toggle switch, shut off the electricity at the circuit breaker handle.[1]XResearch sourceWalter Brant. Handyman.
Don’t confuse air handlers with air conditioners. Air conditioners contain the condenser and are usually set outside the home. Both air handlers and air conditioners are part of the A/C system.
2 Remove the access panel of the air handler unit. Screws and other fasteners on the panel can be removed with a socket wrench, nut driver, or screwdriver. If there is any tape, a reflective metal foil along the panel edges, it should also be removed.
Place the panel and screws aside where they won’t get lost or separated.
If you have difficulties locating the panel, try checking your air conditioning system owner’s manual.
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3 Locate the evaporator coils. These are usually on the air intake side of the fan coil or the outlet side of the furnace. Coils are typically made of copper, steel, or aluminum, and consist of tubes bent in U-shapes and set into an A-frame design of two panels. These panels are lined with thin pieces of aluminum called fins.
Advertisement Method 2 Method 2 of 4:
Using a Pump Sprayer and Brush
Download Article
1 Purchase a pump sprayer, professional cleaning solution, and brush. Professional-grade alkaline cleaning solution for evaporator coils will loosen dirt and mold from inside the coils, the spray wand will reach the tight spaces within the unit, and the bench brush will grab and hook dirt inside the unit.
The pump sprayer should be 1 US gal (3.8 L) to 2.5 US gal (9.5 L) and new, as old pump sprayers may have been used for poisons like weed killer or insecticide.
1 US gal (3.8 L) sprayers work for routine cleaning and lightly soiled coils, while larger sprayers are best for heavy cleaning.
2 Mix the cleaning solution and spray the coils. Follow product instructions for making the cleaning solution. 1 US gal (3.8 L) of spray should be sufficient for a routine cleaning. The spray wand should be adjusted to a narrow .25 in (0.64 cm) spray, but the jet should not be so forceful that it bends the coil fins. This is typically a concern with pump sprayers larger than 2 US gal (7.6 L).
Afterwards, give the coils a few minutes to dry.
Make sure you can see the dirty cleaning solution running down to the condensate drain pan.
To peel off clumps of debris, you may have to direct the spray at the coils from a low angle.
3 Brush the coils, rinsing the brush often. The brush should be rinsed in a new bucket of clean water to ensure there are no residual chemicals or dirt being added to the coils. The brush picks off chunks of dirt and debris too stubborn to be removed by the spray. Never brush across the fins, which can cause them to fold and bend. This will result in blocked air flow.
Short brush strokes ensure your brushing motions will be precisely straight up and down.
To remove loose dirt after brushing, respray both sides of the coils with the cleaning solution.
Alternatively, you can use the brush attachment on a vacuum to remove and suck up all of the dust.[2]XResearch sourceWalter Brant. Handyman.
4 Reattach the evaporator coil access panel and seal with HVAC tape. The metal foil tape should be placed on the top and bottom seams of the panel. Do not tape over the access panel’s manufacturer's label, as service technicians may need that information later.
HVAC stands for heating, ventilation, and air conditioning.
Advertisement Method 3 Method 3 of 4:
Cleaning with Mild Detergents and Water
Download Article
1 Mix warm water and dishwashing detergent in a spray bottle. Use only a few drops of detergent, and make sure the detergent is not highly acidic. Acidic cleaners can cause corrosion to the copper and other metals used in the coil and shorten the life of the coil.[3]XResearch source
You can also use a hand sprayer or garden sprayer.
2 Spray the water/detergent solution onto the evaporator coils. Give the solution a few seconds to a few minutes to soak in and loosen debris. Reapply if needed. You can allow the coil to either drain naturally, or lightly rinse it with some water.
3 Wipe away loose material with a soft cloth or brush. Be careful not to bump the fins on the A-frame, as this may bend them. If you choose to wipe the fins, never wipe them horizontally, as they may fold and later block air flow.
Advertisement Method 4 Method 4 of 4:
Spraying with Commercial Cleaners
Download Article
1 Purchase a commercial cleaner for cleaning evaporator coils. There are several brands available at most home improvement stores. The majority of the cleaners are a foaming type intended to break down debris, then drain away into the unit’s drainage system.
2 Spray the cleaner directly on the coils. Coat the surfaces evenly and thoroughly. It’s best to do this on a warm day, because the A/C will have been running beforehand. That will help rinse the coils with condensate water.
3 Pour 1 US qt (0.95 L) of a bleach/water solution into the drain pan. The bleach and water solution should be half household bleach and half water. This ensures the drain line is free of algae and unclogged. Then, when the foam rinses itself off and drains away, it will properly collect in your unit.
Alternatively, you can buy time-release algae tablets to drop in the drain pan.
4 Pour water down the condensate drain tube. This tube leads away from the drain pan. This will help you verify the tube is draining properly. If it seems the tube is blocked (indicated by something like standing water in the drain pan), discontinue use of the air conditioning system and call an HVAC contractor to clear the blockage.
5 Reapply the cleaner. Repeat until the coils are clean and free of buildup. Make sure you wait until the cleaner liquifies the debris and drains away before applying more cleaner.
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Expert Q&A
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Question What can I use to clean my evaporator coil? Walter Brant Handyman Walter Brant is a wikiHow community member and contributor who has been repairing and restoring houses with over 30 years of experience. He works with homeowners to make a wide variety of improvements to make their homes more comfortable and liveable. Walter Brant Handyman Expert Answer Attach the brush attachment to your vacuum and go over the evaporator coil a few times to clean off the dust build-up. Thanks! We're glad this was helpful.Thank you for your feedback. If wikiHow has helped you, please consider a small contribution to support us in helping more readers like you. We’re committed to providing the world with free how-to resources, and even $1 helps us in our mission. Support wikiHow Yes No Not Helpful 0 Helpful 18
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Co-authored by: Walter Brant Handyman This article was co-authored by Walter Brant. Walter Brant is a wikiHow community member and contributor who has been repairing and restoring houses with over 30 years of experience. He works with homeowners to make a wide variety of improvements to make their homes more comfortable and liveable. This article has been viewed 125,973 times. 41 votes - 85% Co-authors: 7Updated: March 10, 2025 Views: 125,973 Categories: Air Conditioning In other languagesJapanese
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Reader Success Stories
Rick C.
May 15, 2023
"This article helped me but the job to get access to the A coil was difficult because there was no access panel on the weather maker 9200, so I basically had to disassemble a lot of sheet metal, but was doable."..." more
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Yes No Advertisement Cookies make wikiHow better. By continuing to use our site, you agree to our cookie policy. Co-authored by: Walter Brant Handyman Co-authors: 7Updated: March 10, 2025 Views: 125,97385% of readers found this article helpful. 41 votes - 85% Click a star to add your vote 85% of people told us that this article helped them.
Rick C.
May 15, 2023
"This article helped me but the job to get access to the A coil was difficult because there was no access panel on the weather maker 9200, so I basically had to disassemble a lot of sheet metal, but was doable."..." more
Charles Almond
Aug 13, 2022
"Very nice and straightforward article, I'll be doing this within the next month." Share yours! More success stories Hide success stories
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Co-authored by: Walter Brant Handyman This article was co-authored by Walter Brant. Walter Brant is a wikiHow community member and contributor who has been repairing and restoring houses with over 30 years of experience. He works with homeowners to make a wide variety of improvements to make their homes more comfortable and liveable. This article has been viewed 125,973 times. 41 votes - 85% Co-authors: 7 Updated: March 10, 2025 Views: 125,973 Categories: Air Conditioning In other languagesJapanese 
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1 Turn the A/C system off and shut off the electricity to the air handler. Air handler units are located indoors, usually in a closet or attic. Turn off power to the air handler by flipping the toggle switch near the air handler (the switch looks like a light switch). If you cannot locate the toggle switch, shut off the electricity at the circuit breaker handle.[1] 
2 Remove the access panel of the air handler unit. Screws and other fasteners on the panel can be removed with a socket wrench, nut driver, or screwdriver. If there is any tape, a reflective metal foil along the panel edges, it should also be removed. 
3 Locate the evaporator coils. These are usually on the air intake side of the fan coil or the outlet side of the furnace. Coils are typically made of copper, steel, or aluminum, and consist of tubes bent in U-shapes and set into an A-frame design of two panels. These panels are lined with thin pieces of aluminum called fins. Advertisement 
1 Purchase a pump sprayer, professional cleaning solution, and brush. Professional-grade alkaline cleaning solution for evaporator coils will loosen dirt and mold from inside the coils, the spray wand will reach the tight spaces within the unit, and the bench brush will grab and hook dirt inside the unit. 
2 Mix the cleaning solution and spray the coils. Follow product instructions for making the cleaning solution. 1 US gal (3.8 L) of spray should be sufficient for a routine cleaning. The spray wand should be adjusted to a narrow .25 in (0.64 cm) spray, but the jet should not be so forceful that it bends the coil fins. This is typically a concern with pump sprayers larger than 2 US gal (7.6 L). 
3 Brush the coils, rinsing the brush often. The brush should be rinsed in a new bucket of clean water to ensure there are no residual chemicals or dirt being added to the coils. The brush picks off chunks of dirt and debris too stubborn to be removed by the spray. Never brush across the fins, which can cause them to fold and bend. This will result in blocked air flow. 
4 Reattach the evaporator coil access panel and seal with HVAC tape. The metal foil tape should be placed on the top and bottom seams of the panel. Do not tape over the access panel’s manufacturer's label, as service technicians may need that information later. 
1 Mix warm water and dishwashing detergent in a spray bottle. Use only a few drops of detergent, and make sure the detergent is not highly acidic. Acidic cleaners can cause corrosion to the copper and other metals used in the coil and shorten the life of the coil.[3] 
2 Spray the water/detergent solution onto the evaporator coils. Give the solution a few seconds to a few minutes to soak in and loosen debris. Reapply if needed. You can allow the coil to either drain naturally, or lightly rinse it with some water. 
3 Wipe away loose material with a soft cloth or brush. Be careful not to bump the fins on the A-frame, as this may bend them. If you choose to wipe the fins, never wipe them horizontally, as they may fold and later block air flow. Advertisement 
1 Purchase a commercial cleaner for cleaning evaporator coils. There are several brands available at most home improvement stores. The majority of the cleaners are a foaming type intended to break down debris, then drain away into the unit’s drainage system. 
2 Spray the cleaner directly on the coils. Coat the surfaces evenly and thoroughly. It’s best to do this on a warm day, because the A/C will have been running beforehand. That will help rinse the coils with condensate water. 
3 Pour 1 US qt (0.95 L) of a bleach/water solution into the drain pan. The bleach and water solution should be half household bleach and half water. This ensures the drain line is free of algae and unclogged. Then, when the foam rinses itself off and drains away, it will properly collect in your unit. 
4 Pour water down the condensate drain tube. This tube leads away from the drain pan. This will help you verify the tube is draining properly. If it seems the tube is blocked (indicated by something like standing water in the drain pan), discontinue use of the air conditioning system and call an HVAC contractor to clear the blockage. 
5 Reapply the cleaner. Repeat until the coils are clean and free of buildup. Make sure you wait until the cleaner liquifies the debris and drains away before applying more cleaner. Advertisement 
Walter Brant Handyman Walter Brant is a wikiHow community member and contributor who has been repairing and restoring houses with over 30 years of experience. He works with homeowners to make a wide variety of improvements to make their homes more comfortable and liveable. 