Cleaning Condenser Coils

Cleaning condenser coils on your outdoor AC unit will not only help the unit cool more efficiently, but it will also cut down on the power consumption of your AC.  It is important to clean the coils early in the year, before the AC unit is needed for the summer.

Purpose of the Condenser Coils

The outdoor condenser coil of your air conditioner performs a tough job in warm weather. It takes the concentrated heat collected from your home and dumps it into the hot outdoor air. To get rid of the collected heat, your outdoor condenser coil has to move a lot of air. If the coil is dirty or if plants or other objects are too close to the conditioner unit, the fan in the outdoor coil can’t move as much air as required for good performance and efficiency. This raises your electricity cost for air conditioning and may shorten the life of the outdoor condensing unit.

Prior to Cleaning Condenser Coils

Around the outdoor condensing unit of the air conditioner, remove plants and other debris from within 3 feet of the unit in all directions.
Make sure the air’s upward path from the unit is unrestricted for at least 5 feet.
If your outdoor unit is installed under a deck or if someone built a trellis or some other structure above it, either move that structure or hire an air-conditioning contractor to move the outdoor unit.
Most condenser coils are loaded with pollen and dust even when you can’t see it.  If your cooling season is 4 months or more, annual cleaning is an excellent idea. Do not wait longer than 2 years before cleaning condenser coils, and if your summers are long, cleaning more than once a year may be necessary.

Steps to Clean

  • First, and most importantly, turn off the power to the unit.
  • Remove any visible grass and lint from the fins and/or louvers with an old hairbrush or whisk broom.

  • If the aluminum fins on the outside of your outdoor coil have dirt, leaves, or lint stuck to them, it’s time to clean them. An old hairbrush works well for brushing surface dirt and lint off the fins. Brush in the same direction as the slots between the fins so the bristles go between the fins. You can do a better job if you remove the guard grill, which protects the coil. Wear a dust mask to avoid breathing the dust.
  • Then put on a pair of rubber gloves and spray biodegradable outdoor coil cleaner into the coil. Wait five or ten minutes and flush the coil with a gentle water spray.  Use a gentle spray because a strong spray could bend the aluminum fins.
  • If you notice bent fins, you can use either a flat screwdriver or an adjustable fin comb.  Carefully run the screwdriver or fin comb along the fins to straighten them out.  Work carefully and slowly so you do not damage the fins.

That’s it!  Simply restore the power to your AC unit and you’ll have a much smoother running air conditioner.
If you find that there are too many bent fins, or if the AC unit is extremely dirty, you should call a local professional to service and clean it.

For more information on air conditioning see The Homeowners Handbook to Energy Efficiency. Or, for specific information about servicing air conditioners for energy efficiency, see HVAC Systems Field Guide.