How to Clean AC Coils

Air conditioning unit


Tascha Rassadornyindee / EyeEm

  • Working Time: 45 mins
  • Total Time: 1 hr
  • Skill Level: Intermediate

A large portion of our utilities expense is devoted to heating and cooling the air in our homes. And whether you have a central HVAC system, window air conditioner unit, or a ductless wall-mounted unit, keeping it in top condition will help you save money and improve the quality of the air inside your home.

You don't need to be an HVAC technician to give the unit or system a good cleaning to remove dust and grime from filters and coils. You probably know cleaning or changing the filters at least seasonally is important so that the air can circulate freely. But you may have ignored the condenser coils in the air conditioner. The coils hold the refrigerant and as the air passes over the coils the air is cooled. Dust and oily residue from the air settles on the coils and makes them less efficient. Your air conditioner has to work harder and that drives up your utility costs.

How Often to Clean AC Coils

The coils should always be cleaned at the beginning of the spring or summer before you turn on the air conditioner. If you live in a warm climate, a second cleaning is a good idea to get you through until winter.


What You'll Need

Equipment / Tools

  • Screwdriver
  • Coil brush
  • Fin comb
  • Garden hose
  • Step stool


  • Foaming coil cleaner


  1. Access the Coils

    The AC coils are found inside the air conditioning unit. For window units, you will need to remove the unit from the window or be able to reach the exterior of the unit using a sturdy step stool. For wall-mounted units, the coils are found behind the filters and condenser fins (metal grates). For whole-house exterior units, the coils are inside the outer housing. If you are unsure about the location of the coils, consult your manual or the manufacturer's website for more instructions.

    You will need a screwdriver to remove the housing on most units to gain access to the coils.

  2. Remove Loose Surface Soil

    When you have gained access to the coils, check the area for any leaves, insect nests, or dust balls that can be removed by hand. Next, use a coil brush to dust the coils. A coil brush has long, stiff bristles that will reach the coils through the fins or the metal slated-grate. Do not use a heavy hand because the metal fins can be bent easily.

  3. Straighten Any Bent Fins

    If there are fins that have become bent, they should be straightened. Bent fins impede the performance of the coils and keeping them straight increases the exposed surface of the coils and improves efficiency. A fin comb with its more rigid and carefully-aligned teeth will make straightening the fins a simple task.

  4. Rinse Outdoor Unit Coils

    To be sure that coils exposed to outside conditions are completely free of debris, use a garden hose the rinse them down. If a window unit is still sitting in a window, either protect the indoor floor with plastic sheeting or skip this step to avoid possible damage to your interior walls and floor.

  5. Spray on the Foaming Coil Cleaner

    Foaming coil cleaners are available in a standard or no-rinse formula. Opt for a no-rinse formula for interior and window units that are permanently installed.

    Give the can a good shake—just like a can of spray paint—and spray the cleaner directly onto the coils. The cleaner will foam immediately so much that you will not be able to see the coils. The foaming action lifts off any remaining dust and soil in all of the places you were not able to reach with the brushes. Allow the coil cleaner to work for at least 10 minutes or follow the instructions on the product label.

  6. Rinse-Off the Cleaner

    If you are using the standard coil foam cleaner that requires rinsing, use the garden hose to rinse the coils. Start at the top of the unit and slowly proceed down the coils using good water pressure and a back and forth action.

  7. Reassemble the Unit

    Once you have completed the cleaning, reassemble the outer housing of the unit. Be sure to check filters to see if they require cleaning or replacement.

  8. Start the Unit

    Turning on the air conditioner is particularly important for wall-mounted and window units. The action of the condenser and the coils will rinse the foaming cleaner away as the unit operates.