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Cleaning AC coils: A simple step-by-step guide

This is one HVAC maintenance task that you can do on your own in an afternoon. (Score!)

This is one HVAC maintenance task that you can do on your own in an afternoon. (Score!)

If your AC isn’t working as well as it used to, or if it’s not blowing cold air at all, one possible issue is dirty condenser coils.

And if you suspect you have this issue, you’re probably wondering one thing: Can I clean my AC coils myself?

Sure you can. Cleaning your AC coils is a fairly simple process, but it’s important to do it carefully so that you don’t damage your AC unit (or your sanity).

In this article, we’ll walk you through how to clean both the inside and outside air conditioning coils, as well as go over some next steps to take if a thorough cleaning doesn’t improve the performance of your AC unit.

Table of contents:

Ready to make your AC look spiffy and work better? Let’s get to it.

Why you need to clean your condenser coils—and what happens if you don’t

When it’s hot and muggy outside, the last thing you want is for your air conditioner to stop working—no one likes humid, stuffy air in the house. (Well, maybe your kid’s pet iguana, that is, if they have one.) 

If you don’t clean your condenser coils, that’s exactly what could happen: a hot and humid house.

Why? (And just what is a condenser coil, anyway?)

Here’s a quick primer on how AC coils work:

Your air conditioner works by removing heat from the air inside your home and releasing it outdoors.

The process starts when your AC unit pulls in warm air from your home through a return duct. The air then passes over the evaporator coils, which are filled with a refrigerant that absorbs heat. The now-cool air is then blown back into your home through the supply ducts.

The other half of the equation happens outside.

Once the heat has been removed from the indoor air, it needs to be released outdoors. That’s where the condenser coils come in. The hot refrigerant from the evaporator coils passes through the condenser coils, which release the heat into the air outside.

If the evaporator coils on the inside are dirty, then they won’t do a great job of absorbing the heat and humidity in your home. And if the condenser coils outside are dirty, they won’t be able to release heat out of your home effectively. 

Ultimately, if you let dirt continue to accumulate, your AC unit will need to work harder and harder to remove heat from the air.

An air conditioner that’s overworked due to dirty AC coils can lead to a number of problems:

  1. Your AC unit will likely use more energy to perform at the same level, which can lead to higher energy bills.
  2. Your AC fan will run all of the time.
  3. The AC may not cool your house efficiently.
  4. Dirty coils can, eventually, turn into frozen coils, a complete AC breakdown, and a costly repair or replacement. (That escalated quickly! But it’s true.)

In short, it’s important to keep your condenser and evaporator coils clean so that your air conditioner can do its job properly—and so that you can avoid a costly repair bill. 

That means cleaning your AC unit (or paying someone to clean your AC unit!) at least once a year.

How do you clean dirty AC coils, anyway? Well! We’re glad you asked.

Here are the tools and materials you need to clean your AC coils

It’s tempting to just “wing it” when it comes to cleaning (how hard can it be?), but gathering the correct tools before you embark on an AC maintenance project is the most important part of the process—it’s where you really set yourself up for success.

The good news here is that you likely already have many (or all) of the tools involved, even if you’ve never attempted air conditioner maintenance before. Here’s what to gather before you get started:

Tools and equipment for cleaning AC coils

  • Gloves
  • Flashlight
  • Screwdriver or drill
  • Scrub brush
  • A fin comb (an inexpensive specialized brush you probably don’t have in your tool shed—be sure to order one in advance)
  • Hose with a sprayer attachment
  • A shop vacuum, preferably with a wand extension attachment
  • Soap (see below!)

Coil cleaner for AC

A quick word on AC unit soap! You basically have two choices:

1. Purchase a canned, foaming cleaning agent from a hardware store

This is the only option we can vouch for (at least officially). These soaps have been formulated specifically to work on AC coils, and the foaming properties in these products help the soap adhere while it’s doing its job.

If you choose to go this route, look for “AC foaming cleaner,” and purchase a few cans to be safe. Keep the receipt and return what you don’t use!

2. Make your own DIY air conditioning coil cleaner

You can also try mixing up your own AC cleaner. Many people do this, but you’ll need to stick to ingredients that won’t be corrosive to your AC unit (vinegar is probably fine—nail polish remover is definitely not), and give your unit an extra-thorough rinse at the end of the cleaning process.

Necessary disclaimer here: There’s never a guarantee that your DIY air conditioning cleaner won’t damage your unit. Proceed at your own risk!

outdoor central AC condenser unit

How to clean a coil in AC unit—outside condenser

How do you clean condenser coils on an AC unit?

Here’s a quick list of all the steps, and we’ll go over each step in detail below. (And remember, the condenser coils are outside of your house.)

  1. Turn off the power to your AC unit.
  2. Take off the covers on the top and side of the condenser unit
  3. Remove the fan from the unit (this step is optional)
  4. Clean up any debris around (or in!) the unit
  5. Vacuum up any dust or dirt out of the unit
  6. Fix the fins on the condenser coils
  7. Spray down the coils with coil cleaner
  8. Using a hose, spray water onto the coils to remove dirt and dust
  9. Put the AC unit back together

Turn off the power to the AC unit

Before you do anything, you’ll need to turn off the AC unit and disable the breaker. (Look for a switch near the unit, or for a metal box near the outdoor unit—that’s the breaker.)

Don’t skip this step. It keeps you and your AC unit safe.

Take off the covers on the top and side of the condenser unit

Locate the screws or bolts holding the top cover in place, and remove them (a drill can be helpful here). Then do the same for the side cover. You don’t need to be too gentle here—these covers are meant to be removed for cleaning! 

Make sure to set aside all these important bolts and screws in a container so you don’t lose them while working outside.

Remove the fan from the unit (optional)

Using a screwdriver or a cordless drill, remove the fan from the condenser unit. This will give you better access to the coils, and make cleaning them much easier.

By the way, if your unit doesn’t have screws holding the fan in place, or if the task looks too involved, don’t force anything—just proceed to the next step.

Clean up any debris around (or in!) the unit

If there are leaves, sticks, or other bits of debris around or in the condenser unit, be sure to remove them (this is where gloves come in handy).

Vacuum up any dust or dirt

Use a shop vacuum to remove any remaining dust or dirt from the unit. If your vacuum has an extension attachment, use it to get into all the nooks and crannies.

cottonwood seeds causing blockage in AC condenser coils

Fix the fins on the condenser coils

If the aluminum fins on the condenser coils are bent, straighten them out with a fin comb by gently combing through the fins.

This isn’t strictly necessary, but it can help the unit run more efficiently and is a good idea to include in the routine of cleaning AC coils. 

Spray down the coils with coil cleaner

Once the unit is fairly dust-free, it’s time to start cleaning the coils. To start, use your hose to gently wet the coils down. Set your sprayer nozzle to a wider setting so that the water pressure isn’t too intense. 

Use common sense. You want to clean your AC coils—not beat them up!

After you’ve wet the coils down, spray the canned foaming cleanser—which is what we’ll assume you’re using—onto the coils and let it sit for the amount of time specified on the can (usually 5 to 10 minutes).

Using a hose, spray water onto the coils to remove dirt and dust

After the waiting period is over, use your hose to rinse the coils clean.

For best results, start by spraying the AC unit from the inside out, starting at the top of the unit and working your way down. This will help prevent any soap residue from dripping onto clean coils.

Then, step back and hose the entire cabinet from the top down. (Try not to direct the water directly into the AC unit, since this can force any remaining debris back into the coils.)

Put the AC unit back together

Once the coils are clean and soap-free, let the unit air dry for a bit. Then, replace the fan, reattach the side cover, screw everything in place, and turn the power back on to the AC unit.

Voila! A spick-and-span outdoor AC unit. But you’re not quite finished yet: Your indoor units will need some of your attention, too, and there’s no time like the present.

How do you clean evaporator coils—inside AC unit

Now you’re going to walk through how to clean your AC coils that operate indoors: the evaporator coils.

Power off the unit and find the evaporator coils

Before you do anything, make sure the power is off to the AC unit (switch the electricity off at the breaker panel—don’t rely on the on/off button).

Then, remove the access panel on your indoor AC unit by unscrewing the screws or bolts or other fasteners holding it in place. You should now see the evaporator coils, which are the large, flattened tubes located inside the air handler. They should be in an assembly that’s shaped roughly like the letter A. The inside of that assembly will be the dirtiest, so prepare yourself!

Pro tip: If your access panel is held in place by screws, be sure to put them in a plastic bag or envelope so you don’t lose them. It’s also a good idea to take a photo of anything you take apart, just so you have a reference for putting it all back together.

Brush the coils and then vacuum up any debris

Start by using the nylon scrub brush to remove any big chunks of dirt or debris from the coils.

Start from the top and work your way to the bottom. The goal here isn’t to get the coils perfectly clean—just to “jostle out” any large pieces so they fall out of the coils where you can vacuum them up (use a light touch with the vacuum, because the coils are fragile).

Once you’re finished, use your fin brush to straighten out any flattened coils.

Use the foam cleaner to clean the coils

Now it’s time to clean the coils with the foaming cleaner. Spray a generous amount of cleaner onto the inside of the coil assembly and let it sit for 5 to 10 minutes (follow directions on the can, obviously).

After that, you can use your brush (or even just a gloved hand) to lightly agitate any dirt or debris that might still be clinging to the coils. Then, carefully rinse the coils with water from a spray bottle. (Please don’t hose down your indoor unit. It will hate the experience and your carpet will stink for days.)

Air conditioner evaporator coil cleaning of indoor unit with spray foaming coil cleaner

Dry the coils and put everything back together

Use a soft towel to dry the coils as much as possible (don’t use a blow dryer, because this can damage the coils). Alternatively, you can just leave the access door open until the coils air dry. Either works!

Then, screw everything back in place, turn your AC unit back on, and enjoy the cool blast of air from a happy climate control system. All is well in the world of HVAC, right?

Well, maybe.

What to do if cleaning AC coils doesn’t fix the problem

Unfortunately, sometimes cleaning your AC’s coils doesn’t completely fix the issue.

And if you’ve cleaned the coils but your AC unit is still struggling, it might be time for a more serious repair like a coil replacement.

A quick warning on coil replacements, though: They’re not cheap. In fact, they can be quite expensive, depending on the make and model of your AC unit. So, before you decide to replace the coils, it might be worth considering whether or not it’s time for a new AC unit altogether. (Here’s how to know when your HVAC is ready to be replaced.)

And while that might seem like a biased suggestion, it’s really a matter of mathematics: Often, the cost of coil replacement (plus the cost of additional maintenance and repairs for your aging AC) can add up to more than the cost of a new AC unit. 

It’s often a better deal in the long run to upgrade to a newer, more efficient system (such as a heat pump).

There’s also another possibility, which is that your AC’s coils aren’t your problem at all. In fact, your AC unit could be suffering from a number of other issues including:

  • Dirty air filters
  • Clogged condenser
  • Iced coils
  • Low refrigerant levels
  • Incorrect sizing
  • Broken compressor

(Want to diagnose? Learn more about why your AC isn’t working.)

Finally—and this is important—if you’ve had continued cooling issues (or uneven cooling in your house), there’s a very good chance that your air conditioning might not be the problem—or, at least, not the only problem. 

If your house hasn’t been professionally air sealed, then at least some of your cooling issues are actually because of heat gain from air leaks

And if your attic or roof hasn’t been insulated in the past ten-ish years, then hot air is almost certainly invading your house through the roof (hello, stale and stuffy air!).

For a quick explainer on why and how air sealing and insulation work to keep your cool air inside, take a look below.

It’s also important to know that insulation breaks down over time, so depending on the type of insulation you have and when it was installed, it may already be time for an upgrade. (And depending on when your house was built, you may have entire attics you don’t know about that are uninsulated.)

In fact, the most likely scenario is that you’ve got a number of issues contributing to your HVAC problem.

And if that seems overwhelming, don’t worry—there’s a solution on the way.

Fix your cooling problems permanently—for zero upfront cost

The truth is that figuring out an effective solution for your home’s air conditioning is… actually pretty complex!

An effective climate control solution—one that actually fixes the problem and makes your house feel amazing—will be thoughtfully designed and completely customized to your home, situation, and preferences.

And you can’t YouTube your way to that kind of expertise—it’s definitely a job for experienced specialists. That’s where Sealed comes in.

The entire house has stayed much more comfortable and consistent. Sealed made my home modern without having to look modern.

Gretchen H., Sealed customer

If you’re tired of dealing with AC issues, consider calling us in.

If your home is eligible for a Sealed home comfort makeover, our experts will take charge of the situation and develop a custom plan that will make your house feel fantastic.

Then, once you make any tweaks you like, we’ll actually make that plan happen.

We’ll oversee the project. We’ll hire home specialists that have been verified and certified in your region. We’ll negotiate all the costs and be responsible for the results.

All you need to do is enjoy your home. (And after we get through with your house, it’ll be as comfortable as a home should be.)

Even better: If you qualify, you can get a new HVAC system, high-performance insulation, and professional air sealing for zero upfront cost.




August 26, 2022