Tips on How to Clean Air Conditioner Coils

With July being called the hottest month in recorded history, access to air conditioning is literally becoming a matter of life and death. As AC use increases, so too can issues. One simple yet important way to keep your customers’ AC units working efficiently for the rest of the summer involves just a few tools and a little elbow grease: cleaning the coils.

Here’s a quick reminder of the difference between an AC’s evaporator and condenser coils.

Evaporator Coils 

In most AC systems, a fan pulls hot air and moisture from inside the home or building and passes it through the evaporator coil (or cooling coil). The coil cools the air using a liquid refrigerant that absorbs the heat and then turns it into gas. Evaporator coils are usually housed near the air handler where the blower fan sends out the cooled air.

Condenser Coils 

The condenser coil works together with the evaporator coil in what’s called the heat exchange cycle. The hot refrigerant gas that the evaporator coil creates is sent to the AC’s compressor. The compressor pressurizes the gas and sends it to the condenser coil. As the coil releases the heat and the refrigerant turns back into liquid, a fan blows to help dissipate the captured heat into the outside air. The newly liquified refrigerant then goes back to the evaporator coil and the process starts all over again.

Why Cleaning AC Coils Is Important 

As explained above, a vital part of the heat exchange loop is airflow. Hot air must pass through the evaporator coil for cooling, and the condenser coil must be able to dissipate the rejected heat outside, usually aided by a fan. 

If the coils become dirty from too much dust or debris, they’ll have a harder time transferring heat into and out of the space. As you’ve probably seen many times, AC units that are forced to work too hard for too long are prone to fail.  

While dirty coils are less urgent than total system failure, an important point to tell your customers is that they usually equate to higher cooling costs. If you or your employer offers an annual AC maintenance plan, make sure you check both the evaporator and condenser coils. The U.S. Department of Energy recommends checking them every year and cleaning them as necessary. 

When you come across a customer whose AC unit is in desperate need of cleaning, here are some tips that will help you ensure you have a satisfied (and cool) customer. 

The Best Ways to Clean Air Conditioner Coils 

While cleaning an AC’s evaporator and condenser coils could be a DIY project for your customers, most HVAC manufacturers advise against it. The average homeowner likely won’t consider factors such as the fragility of the coils or the possibility of electric shock when accessing the AC’s components, making coil cleaning a great opportunity for serving your customers.

Tools and Materials Needed for Cleaning Coils in an AC Unit

With the right tools, cleaning air conditioner coils can be a quick and simple service. Here are some items to remember to keep with you during your next service call just in case coil cleaning is necessary: 

  • Gloves to protect yourself from potentially sharp coils
  • A fin comb for straightening out any bent coil fins
  • Compressed air or a shop vac for removing debris from the outdoor condenser coil
  • A gentle spray nozzle for a hose, or a portable coil cleaner system like a CoilJet if you have no access to water
  • Chemical coil cleaner for superior dirt and grime removal
  • A soft bristle brush or cloth for wiping up any stuck-on dirt

Safety Precautions 

Before you dive in and start cleaning your customer’s AC coils, keep these safety tips in mind to protect yourself and the air conditioning unit. 

It should go without saying, but we will say it anyway: Remember to cut power to the entire AC unit. Don’t just use the thermostat — find the breaker near the indoor air handler or by the outdoor condenser and flip the switch or remove the fuse.  

After ensuring no power is getting to the air conditioner, use protective gloves when touching or cleaning any coils by hand. The edges of coil fins can be sharp, and any bent fins can rip through a cloth and cut your hands.

If you need to use a chemical coil cleaner, resist the urge to think that “coil cleaner is coil cleaner.” Different cleaners are usually designed for different purposes — like specific formulations for evaporator and condenser coils.

After determining the correct cleaner to use, remember the following:

  • Never mix different brands.
  • Always read the label and follow the directions.
  • Wear the necessary protective gear.
  • Never use acid-type cleaners indoors.
  • Always spray downwind when cleaning outdoor condenser coils.
  • Use a gentle hose nozzle to rinse off chemical cleaners, never a high-powered pressure washer. Too much water pressure can damage the coil fins.

How to Clean Air Conditioner Evaporator Coils 

When servicing the AC evaporator coils in a traditional split system, remove the service panel and inspect for dirt, debris, and damage. If you see excess dust or grime, start the cleaning process. 

Because the evaporator coil is indoors and near the air handler, avoid using compressed air to remove dust or debris. Doing that can spread the dust all over the air handler and potentially cause problems later. Instead, use a soft bristle brush or shop vac with a brush hose attachment to remove as much surface dirt or lint as possible. 

If you see a lot of oil or grease on the coils, you can use a chemical cleaner (after making sure it’s non-acidic and safe for evaporator coil use) and gently rinse using a spray bottle. You could also use a homemade mix of water and mild detergent (like dish soap) instead of commercial chemical cleaners. 

After cleaning the coils, it’s also a good time to inspect the other parts of the unit. Inspect the condensate drain pan and remove anything that doesn’t belong there. Flush the drain tube with clean water and check for clogs. If the drain line has a bad clog, remove it to keep it away from the coils and use either a wet/dry vac or high-water pressure to remove the blockage.

How to Clean Air Conditioner Condenser Coils 

Since the condenser is located outside in a split system, the coils are far more likely to be dirty than the evaporator coils located inside near or above the air handler. Thankfully, the cleaning process for outdoor condenser coils is relatively similar to cleaning the evaporator coils. 

Depending on the type of outdoor condenser unit, accessing the coils may be as easy as removing a simple metal wire coil guard. Or you may need to disassemble an entire outer panel and remove the exhaust fan. If you’re not familiar with the type of unit you’re dealing with, make sure you find the maintenance manual online before you start taking anything apart.  

Once you have access to the coils, it should be obvious to you if they need a good cleaning. If there are multiple rows of coils, check for dirt buildup in between the rows. Like with the evaporator coil, start with a soft brush or shop vac to remove dirt and debris from the coils, but also clean the base of the condenser unit. Brushing the coils also helps improve cleaner penetration.  

You can also use compressed air to remove dirt buildup. Just make sure you spray the coils straight through the fins, not at an angle, and spray the air in the opposite direction of the operating airflow (usually meaning from the inside of the condenser unit outward). 

If necessary, prepare your chemical cleaner by carefully following all instructions — remember, “the label is the law!” Foaming aerosol cleansers can be simpler than liquid cleaners that need to be mixed with water using specific ratios. But use whichever type works best for you.  

When ready, rinse the coils with water to prepare them for the cleaner. Then, spray the cleaning solution from the inside using slow sweeping motions. Start from the top and move your way to the bottom to prevent any cleaning solution from getting onto clean coils. Let the solution sit for the amount of time specified on the label (usually 5 to 10 minutes), then rinse using low pressure. 

If possible, let the coils dry for a bit before reassembling the condenser unit. Use that time to talk to the customer about what you did, start cleaning up your gear, or pet any friendly dogs that watched you work from inside.

More Resources 

If you didn’t already know, now we hope that you see that the importance of cleaning AC coils cannot be overemphasized. If you’re craving even more detailed information about cleaning AC coils, check out our sources below. And if you’d like to complete your required HVAC continuing education from the comfort of home, consider our online courses! We design our courses to work around your busy schedule by allowing you to complete them at your pace. To get started, click on the “HVAC” button in the top menu and select your state.


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Reeves, C. (2018, July 31). HVACR Tech Tip: How to Properly Clean a Condenser Coil. Retrieved from

Trane. (n.d.). How Does Central Cooling Work? Retrieved from

U.S. Department of Energy. (n.d.). Maintaining Your Air Conditioner. Retrieved from