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How to Clean AC Coils

Updated
Cleaning AC coils is vitally important to the health of your AC unit.

An air conditioning unit is a life-saver on hot summer days. When you’re sweating and miserable, the last thing you need is for your AC unit to malfunction. But if you’ve not cleaned it recently, this can easily happen.

It’s important that you clean your AC coils every year. They are subject to a build-up of dirt, dust, and other home contaminants. Over time, this prevents your AC unit from working well.

We’ll walk you through how to clean both evaporator and condenser AC coils. While it isn’t a super quick process, we think — with our help — you’ll get the hang of it. Plus, it can save you hundreds of dollars every year.


How an Air Conditioner Works

Air conditioning works by cooling down the air inside your home.

The compressor coil in your AC unit absorbs heat from inside your house. It comes in through a vent, then blows over the evaporator coil. This coil cools the air, and a fan blows the air through the air ducts back into your hose, cooling you down on a hot summer’s day.

This process repeats until your house reaches your set temperature. The refrigerant fluid becomes a hot vapor; the outside air absorbs the heat, lowers the temperature, and changes the fluid from gas to liquid. The liquid travels back to the evaporator, which is then blown through your air ducts as nice cool air.

Let’s walk you through the two types of coils, condenser, and evaporator.

Condenser Coils

The condenser coils are located outside in the metal unit called the condenser. These metal tubes run through aluminum fins. The gas refrigerant gets compressed in the coils, then becomes a hot liquid. The coils then dissipate heat as the liquid travels through to the fan on the condenser unit, which disperses the heat.

To summarise: the condenser coils soak up the heat in your home and move it outside.

Evaporator Coils

These coils are located inside near the air handler. As opposed to condenser coils, evaporator coils are cold. That’s what ensures the AC unit sends cool air through your home.

These coils run through aluminum fins also, but the refrigerant goes from liquid to gas instead. The gas cools down the coils so that the coils stay cold, and therefore, so does your home.

Where to Find AC Coils

Condenser coils are located outside in the condenser unit. You might find it on the opposite wall from your electric service panel.

Evaporator coils are located indoors, inside the air handler. They’re usually on the supply side of your air conditioning unit, behind the access door. You might need to remove screws to access it.

How Often to Clean AC Coils

We recommend cleaning your AC coils at least once a year. Certain manufacturers might recommend cleaning them 2-3 times a year.

But why?

Well, there are many benefits to cleaning your AC coils. First of all, it increases the efficiency of your AC unit. If dust and debris are left on the coils, the unit won’t work as well, and the air won’t be as cold. It might take longer for your house to cool down, which will cost you more money.

Another reason to clean your AC coils regularly is because a lot of dirt and dust accumulates in there. It can then blow back into your house, contaminating the air. If you already have allergies or are immuno-compromised, this will be hazardous to your health.

How to Clean AC Coils Without Removing Them

You don’t have to take your whole unit apart to clean your coils. We’ll show you a thorough method for how to clean your air conditioner coils with a vacuum cleaner and commercial coil cleaner.

Keep in mind these instructions are for central HVAC units rather than portable or window unit air conditioners.

  • Time: 2 hours
  • Difficulty: Intermediate

What You’ll Need

  • Screwdriver
  • Shop vacuum (wet/dry vacuum with a brush attachment)
  • Protective gloves
  • Coil cleaning solution
  • Garden hose
  • Flashlight
  • Cloths
  • Spray bottle
  • Cleaning brush (optional)
  • Compressed air (optional)

Condenser Coils

Let’s start with how to clean condenser coils — these ones are located outside.

1. Disconnect the Power

Safety first! Turn off the power to the system. Unplug it if that’s an option. Otherwise, you’ll need to turn off the power at the electrical service panel.

2. Access the Interior

To clean condenser coils, you need to access the unit’s interior. This means removing the cover. Usually, you can do this with a screwdriver. Loosen the screws and remove the top of the unit. If in doubt, check your user manual for specific instructions.

Quick Tip

If you want to see how dirty the coils are, shine a flashlight from the inside of the coils through to the outside. Looking at the outside, you will barely see the flashlight light, especially if the coils are really dirty. When you’ve finished these steps, you should see the bright flashlight light. That’ll show you how good a job you’ve done cleaning your coils.

3. Remove Debris

When you look inside the unit, you might notice a lot of debris. Wearing your protective gloves, remove bulky debris (like leaves and twigs) by hand. Use your shop vacuum to hoover out the rest of the debris from the bottom of the unit.

Next, put your brush attachment onto your shop vacuum and clean out the coils. The force of the vacuum will pull out debris from the coils, making the next few steps easier.

4. Apply Coil Cleaner

Using your purchased coil cleaner, follow the packaging instructions to apply it to the coils. Usually, you will simply spray the coils with the cleaner and leave for a few minutes.

Don’t be alarmed if you end up using an entire can to clean your coils.

Top Tip

We recommend using a foaming cleanser such as the HVAC Guys Foam Blaster, because the foaming action will lift the dirt from the coils and flush it out. Plus, it’s easier to apply.

5. Hose Coils

Using your garden hose on a low setting, rinse the cleaner from the coils. Ensure you rinse away all of cleaning solution residue, but try not to completely flood the unit.

Check your manufacturer instructions to make sure that it’s okay to hose down the unit. Because these units live outside, they’re usually waterproof and fine to wash with water.

6. Wet Vacuum

Use your shop vacuum on the wet vacuum setting to remove excess water.

7. Air Dry

Leave the cover off of the unit and let it completely air dry for at least one hour.

8. Reassemble and Turn On

If you want to see how clean your coils are now compared to before you started, do the flashlight test again!

Once complete, place the cover back on the unit and screw it in. Carefully reconnect it to power and turn the unit back on.

Evaporator Coils

Next up — how to clean evaporator coils. Evaporator coils are located inside.

1. Turn Off Unit

Disconnect the power to the air conditioning unit and turn the power off at the breaker.

2. Access Coils

You might need to unscrew the unit to access the interior. Remove the cover so you can access the coils.

3. Vacuum Carefully

Using your shop vac with a brush attachment, very carefully vacuum the unit’s interior and the coils. Remove as much debris and dust as possible.

4. Spray Coils

Using your coil cleaner, spray the coils from the outside in if possible. If not, you can just spray the coils from inside the unit. Make sure to read the packaging instructions to check how long you should leave the product on the coils. Usually, this will be about 10 minutes.

5. Rinse Coils

Fill a spray bottle up with water and spritz the coils, working in one small section at a time. You don’t want to oversaturate your indoor AC unit. So only spray a little water, then wipe it away with a cloth before moving to the next area. Repeat this step until you’ve rinsed all the coils.

Quick Tip

There are coil cleansers available on the market that do not need to be rinsed such as the Evap foam from Nu-Calgon and the Foam Blaster from HVAC Guys.

6. Blow With Compressed Air (Optional)

If your coils are still dirty, and there’s lots of dirt built up between the fins, you might need to utilize the power of compressed air. Blow in between the fins to dislodge dirt and debris. This can take up to an hour, depending on how dirty your coils are, but this is a critical step if it’s been a while.

7. Vacuum Again

Using the wet function on your shop vac, vacuum the unit’s interior again to remove any loosened dust, debris, and excess water.

8. Dry Unit With Cloth

Using clean cloths, wipe down the AC unit and coils to dry them off.

9. Reassemble

Reassemble your AC unit and reconnect to power.

What Can I Spray My AC Coils With to Clean?

While we recommend a commercial coil cleaner, you might want to try something else.

Your best option for a homemade cleaner would be mixing water and a tablespoon of household detergent or dish soap. Add a tablespoon of baking soda for extra cleaning power.

Avoid acidic cleaners, especially if you have copper coils. The acid can cause corrosion.

How to Clean the Inside of an AC Unit

When you’re in the AC unit, you might as well clean the rest of it. Here are some other handy cleaning instructions to deep clean the whole thing.

  1. Clean the drain pan: Mix hot water and a few drops of dish soap. Pour the solution down the drain. If the solution doesn’t go down the drain easily, there might be some clogs.
  2. Unclog the drain pan: Go to the end of the drain and hoover out any clogs using your shop vac. Hold the vacuum hose at the end of the drain tub. Make an air seal by holding a towel around the gap. Run the vacuum for a few minutes to clear clogs.
  3. Change the filter: You should change the blower filter twice a year, so you can time this with cleaning your coils. Make sure you choose a filter with the same airflow rating and swap it out following your manufacturer’s instructions.

When to Call a Professional

There are a few instances in which we would recommend calling a professional.

  • Deep cleaning: While you can attempt a deep clean yourself, a professional will do a more thorough job. If it’s been years since your coils have been cleaned, call a professional.
  • Damaged fins: You can straighten out damaged fins with a fin comb, but call a professional if the fins are genuinely damaged.
  • If you’re uncomfortable: Cleaning AC coils aren’t everybody’s area of expertise. You might be feeling overwhelmed, even with our thorough tips. So if you’re uncomfortable with this cleaning task, call up a professional to help.
  • Unit not running properly: If your unit isn’t running properly even after cleaning the coils, call a professional to inspect the unit.
  • If you live in an apartment: In a shared building, you should call a professional. There’s a good chance you share electricity to your air conditioner with other residents. Also, you might have a tough time accessing the outside unit.

Extra AC Maintenance Tips

Cleaning your AC coils is just one part of maintaining your unit. Here are some other top tips for keeping your AC system in mint condition:

  • Replace filters: Replace your filters twice a year, following your manufacturer’s instructions. Make sure to use the same airflow rating.
  • Wait: After cleaning your AC coils, don’t use the unit for another 60 minutes to ensure that the unit is dry.
  • Use a timer: Keep your air conditioner running on a timer. Set it to a higher temp when you’re out and cooler when you’re home. Try not to turn it off completely (unless you’re going on vacation); otherwise, it will use more energy to cool down your house later.
  • Keep plants away: Make sure there aren’t plants, weeds, or other obstacles within a few feet of the unit. The unit needs good airflow to work properly.
  • Check drains: Check the drains regularly to ensure that they don’t become clogged. Algae growth can easily clog drains. Flush the drains from time to time using dish soap and warm water. Vacuum with a shop vac.
  • Fix fins: Crushed and bent fins can end up affecting the airflow. So use a fin comb to straighten them out.
  • Insulate areas of your home: To stop your AC unit from working overtime, insulate hot areas of your home — such as in the attic — to keep them cool.
  • Keep unit cool: Keep your home cool during the day. Draw blinds or shut curtains. Install awnings over south-facing windows. Have your ceiling fan on as well, especially on hot days.

FAQs

Can I Use Oven Cleaner on AC Coils?

We’ve done a lot of research to put together this guide, and not once did we see any expert advice on using oven cleaner to clean AC coils. So no — don’t use oven cleaner on your coils.

Will Vinegar Hurt Evaporator Coils?

If your evaporator coils are made from copper, don’t use vinegar. The acid in the vinegar can corrode your copper coils over time. For aluminum coils, cleaning with vinegar is an okay solution. Always dilute it in a 1:1 ratio with water.

Check your manufacturer’s instructions to see what they say about vinegar.

Overall, we recommend a coil cleaner rather than vinegar. If you want to use a DIY solution, water and dish soap is best.

How Much Should AC Coil Cleaning Cost?

If you’re cleaning coils yourself, the main things you’ll need to buy are a shop vac and coil cleaning solution. On average, a shop vac costs around $100, and a cleaning solution costs around $15. So to do it yourself, it should only cost around $15 every year.

For professional cleaning, you’re looking at between $100 – $400 each time. That’s why we recommend doing it yourself!

How Long Before I Can Turn on my AC After Coil Cleaning?

Wait one hour before using your AC unit again. This gives it time to air dry thoroughly.


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About the Author

Beth McCallum

Beth McCallum is a 20-something freelance writer & book blogger with a degree in creative writing, journalism and English literature. Beth firmly believes that a tidy house is a tidy mind. She is always looking for new ways to sustainably clean and tidy her house, that's kind on the environment but effective in the house, too!