Interior Heating & Cooling Heating

How to Clean Air Conditioner Coils

Want to save money and lengthen your AC unit’s life? Follow this easy-to-follow maintenance regimen for cleaning the inside of your air conditioner.
Theresa Clement Avatar
how to clean ac coils

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During the hottest days of the year, it’s likely that you rely heavily on an air conditioning unit—be it targeting your room from a windowsill or cooling off the whole-home—without considering what makes it tick.

The magic happens because of the AC condenser coils. Here, the refrigerator unit in your go-to seasonal appliance absorbs heat to make the air cooler. As air passes over the cool refrigerant, it wicks the heat out in a process that’s essentially the reverse of how your forced air furnace operates.

Now, the cleaner the surface area of those coils is, the more efficiently the machine works. Dust and oil that accumulate over time can create a blanket over the coils—one that, just like the blanket on your bed, impedes heat transfer and makes your AC less efficient and more expensive.

Fortunately, the hardest part to cleaning air conditioner coils is remembering to set aside the time at least once a year. The coil cleaning process usually takes less than half an hour, but better schedule a full hour so you don’t feel like you’re rushing through the job. The steps below will guide you through how to clean ac coils to maximize the efficiency and lifetime of your machine.

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How to Clean AC Coils

STEP 1: Locate the AC coils on your unit. 

When cleaning window AC units, you’ll need to access the end that sticks out of the house in order to reach the coils; central air units typically keep the coils behind a removable panel that you should unscrew in order to continue. Check your operator’s manual if you’re unclear—the specs diagram will identify exactly where the coils are and the process to remove the cover. Remember: When in doubt, trust the manufacturer’s advice. They built it the machine, and they know how to take it apart.

STEP 2: Inspect the dirty condenser coils.

Visually inspect the coils for any large debris like leaves, spider webs, or clods of dirt. Remove these by hand, then dust off the coils using a coil brush. Available at most big box hardware stores and AC shops, this specialty cleaning tool (also known as a soil brush) features bristles with stiffness about halfway between a hand broom and a wire brush. Lightly guide the brush parallel to the fins on the coils in order to avoid bending them. This isn’t a deep scrub. You’re simply knocking off loose dust and hair.

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STEP 3: Correct bent fins with a fin brush.

Did you notice many bent fins on your coils in Step 2? (Hint: Bent fins will reflect light and often put a bright sheen to parts of the coils.) If so, running a fin brush slowly and parallel to the line of the fins could straighten them out. This will improve the performance of your AC unit by increasing the exposed surface area for the coils.

If you don’t want to invest in a piece of specialized equipment like the fin brush (which can be purchased for $15 or more online), go ahead and skip this step. Correcting bent fins goes above and beyond the task at hand—cleaning the coils—from which your machine will already receive an efficiency boost.

how to clean ac coils

STEP 4: Rinse the AC coils with water (optional).

As AC coils are typically made from copper or aluminum, they can be cleaned with water. Rinse the coils on any outdoor central AC unit by spraying with water from your garden hose on a low setting.

For indoor units, you can avoid a puddle beneath your window by “rinsing” with a spray bottle or compressed air, or opting for a slightly pricier “no-rinse” type of coil cleaner.

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STEP 5: Apply the AC coil cleaner.

Many coil cleaners are safe to use on both aluminum and copper coils, but check the packaging before applying a cleaner to the coils. If the coils are made from copper, avoid using acidic cleaners because they can cause corrosion. For aluminum coils, a soapy mix of household detergent is also safe to use.

To use a foaming HVAC coil cleaner, shake the can and spray it directly into your coils so they are completely covered. The cleaner should foam immediately, filling the air between coils where grime accumulates. The foaming lifts off all the unreachable dirt and grime embedded in between the fins. Let the cleaner soak for 5 to 10 minutes, according to the instructions on the can.

how to clean ac coils

STEP 6: Rinse the A/C coil cleaner (if specified).

If the cleanser label says to do so, rinse off the foaming cleaner using your hose. You will need good water pressure and slow, back-and-forth motions to thoroughly rinse the cleanser off. Indoor units cleaned using rinse-free cleaner simply need to start up; the condensate will rinse off the cleaner on its own.

Though some of the more unscrupulous AC service companies will say you need service two or three times per year, most experts agree that once a year is enough for cleaning your AC coils. For best results during the warm months, do it in the spring, immediately before the summer heat starts to demand your air conditioning perform at peak potential.

how to clean ac coils

Final Thoughts

Knowing how to clean AC coils is an important part of making sure the air conditioner runs efficiently and effectively. Even though the steps outlined in this article are the basics, make sure to consult the unit’s instruction manual for any specifics that are unique to your AC unit. While it takes under an hour to clean coils, make sure to have all of the tools on hand and complete the cleaning before the warmer temperatures are expected.

FAQs About How to Clean Condenser Coils 

A clean air conditioner works better than an under-maintained unit. The steps to cleaning condenser coils are fairly straightforward. However, every situation is unique. Below are some answers to popular questions about how to clean condenser coils in an AC unit.

Q: What does a condenser coil look like?

An AC’s condenser coil is made of metal and looks like tubes.

Q: What happens if you don’t clean your AC coils?

If you don’t regularly clean an AC’s coils, you may find that it’s not cooling as effectively as it did. Over time, dirty AC coils will cause the unit to use more power and eventually wear out.

Q: How long before I can turn on AC after coil cleaning?

Make sure the air conditioner is completely dry before attempting to use it. Wait about 30 to 60 minutes before turning on the AC after cleaning the coils.

Q: Can you clean an AC coil without removing it?

Yes, you can clean an AC coil without removing it from the unit. Use compressed air in a canister to blow the dirt and debris free.

Q: What if my AC condenser coils need a deep clean? 

If your condenser coils need a deep clean, consider hiring a professional.