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How To Clean AC Coils? A Minneapolis Tech Answers

The coils in your AC system play an important role in the cooling process. But when they become dirty, they decrease your AC’s ability to run efficiently and keep your home comfortable. 

We’ll tell you right off the bat it’s best to let a professional handle coil cleaning for the following reasons:

  • AC coil cleaning requires special tools: Chances are, you don’t have the required tools lying around the house. 
  • AC coils are fragile and can be easily damaged: A professional knows how to delicately handle the coils, preventing any damage during cleaning. Coils are expensive—the last thing you want is to break one during cleaning and have to pay for a professional repair.
  • Hiring a professional is faster: An experienced professional has probably cleaned thousands of AC coils. They know how to do the job quickly and efficiently. If you try the cleaning yourself, it will take longer and you’ll have to factor in additional time going to the store and getting the needed equipment.

But if you’re feeling particularly handy, or just want to see what’s involved in coil cleaning, we’ll explain the process step-by-step below.

But first, let’s take a quick look at what AC coils do and where they are located to give you some context.

Want a professional to clean your AC coils? Our trustworthy technicians can get the job done right—in no time.

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What AC coils do (and where they are located)

First off, a central air conditioning system actually has 2 sets of coils: 

  1. The evaporator coil (in the inside unit)
  2. The condenser coils (in the outside unit)

We’ll explain how both of these coils work below.

The evaporator coil

The evaporator coil is located in the indoor unit of your AC system, called the air handler. The evaporator coil is responsible for cooling the air inside your home.

The evaporator coil works like a sponge—it absorbs heat and moisture from the air inside your home, which turns the air cold. This cold air is blown back into your home, which lowers the indoor temperature.

So, what happens to all the heat that the evaporator coil absorbs? That’s where the condenser coils come in…

The condenser coils

The condenser coils sit inside the outdoor unit. The condenser coils collect all the heat absorbed by your evaporator coil. The big fan inside the outdoor unit blows cool air over these hot coils to release the heat into the outdoor air.

For more information about the AC cooling process, read our blog, “How Does Central Air Conditioning Work? A Minnesota Tech Explains.

Now that you know a little background about what these coils do, let’s look at how you can clean them. We’ll start with the outdoor coils since those are the easiest to clean.

How to clean the condenser coils

Since the condenser coils are located outside, dirt can easily coat them. If these coils are dirty, they will struggle to release heat into the outside air, which can lead to problems like higher energy bills and breakdowns.

We’ll explain how to clean these coils step-by-step below:

Step #1: Turn off the air conditioner

Go to the outdoor unit. You should see a small electrical box on the wall next to the unit. Open the panel and push the button (or flip the switch) to the OFF position. This will shut off power to your AC.

Caption: The inside of the electrical disconnect box

Step #2: Remove sticks and leaves from the outside unit

Next, remove sticks, leaves or other debris that are stuck in the outside unit’s protective covering. 

Caption: An outdoor unit with leaves stuck in it

Step #3: Remove the top of the condenser

Using a screwdriver, you can take off the top of the condenser (with the fan attached) to access the inside of the condenser. This is where you’ll find the coils.

Caption: The top of a condenser unit

Step #4: Spray the coils and coat with coil cleaner

Locate the coils (the copper lines) inside the outdoor unit. Set your hose to a low or medium setting and begin spraying the coils, from top to bottom. Be careful not to soak the fan motor as you spray the coils.

Once you’ve sprayed the coils with water, you can apply a generous amount of coil cleaner. Let the coils sit for 10 minutes after you’ve sprayed them with the cleaner. 

To make sure the coil cleaner won’t harm the equipment, we recommend consulting with the manufacturer or a professional HVAC tech for advice on which coil cleaner to use.

Step #5: Rinse the coil cleaner

Next, rinse the coils with water to wash away the coil cleaner. This will flush the cleaner and any remaining dirt and debris to the outside.

Step #6: Wash the fins

Then, spray water over the thin metal fins surrounding the coils. The best way to do this is to start at the top right corner and spray in rows all the way to the bottom.

Step #7: Reattach the lid and turn your AC back on

After you’ve completed the final rinse, you can screw the lid on and activate the power again. If you notice any problems with your air conditioner after you clean the coils, call a professional for assistance.

How to clean the evaporator coil

While your air filter should remove most dust and large particles from ever reaching the evaporator coil, the truth is dust still sneaks in and can build up on the evaporator coils.

If the evaporator coil isn’t cleaned, mold can easily form, which leads to unhealthy air and a nasty musty smell throughout the house.

We highly recommend leaving an evaporator cleaning to professionals for the following reasons:

  • The evaporator coil is typically located in a hard-to-reach space (like the attic, basement or crawl space), which makes cleaning these coils dangerous and difficult for most homeowners. 
  • The evaporator coil is especially sensitive and can be easily damaged if handled incorrectly. Since an evaporator coil is expensive to replace ($1,000+), we recommend leaving the cleaning to a professional. 
  • The evaporator coil may need to be removed from the air handler for a thorough cleaning. Removing the coil is complicated, so it should only be done by a professional.
  • Cleaning the evaporator coil yourself can void your AC warranty. Most manufacturers will only honor your warranty if a certified HVAC professional handles all major maintenance and cleaning.

The bottom line: A certified AC pro will have the tools and know-how to clean the coils correctly, which can save you from an expensive repair in the future.

Need AC coil cleaning? Let a Twin Cities expert help

Our trained (and trustworthy) technicians can get the job done in no time. We’ve cleaned thousands of air conditioners for residents in Minneapolis-St. Paul since 1918.

Call us today (651) 228-9200 or schedule an online appointment.

Schedule an appointment today

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