How Often Should Evaporator Coils Be Cleaned?

The evaporator coils (located inside the air handler or furnace) and condenser coils (usually outside the unit) are critical components of your air conditioning system. They absorb the heat and humidity from the air that passes through them and disperse it outdoors. But when they get coated with dirt and other contaminants, the transfer of heat is hindered. The result is poor cooling and higher energy usage that may shorten your equipment’s lifespan.

When the evaporator coils are cleaned regularly, they disperse that heat and humidity back into the air and your system can function as it should. But if they aren’t, you may notice that the air is less humid than usual or that it takes longer for your air conditioner to cool the space. The good news is that it’s relatively easy to clean evaporator coils.

Ideally, you should clean them twice a year: once in the spring before turning on your air conditioner for summer and again in the fall before shutting it down for winter. During these maintenance procedures, you should also clean the outdoor unit’s condenser coil and the indoor evaporator coil.

First, disconnect the power to the coils by shutting off the circuit breaker at your home’s electrical panel. Next, remove the screws or bolts that hold on the panels to gain access to the coils.

If the coils are lightly soiled, you can use compressed air to blow off loose debris, working in the direction opposite of normal airflow. If you do this, be sure to wear eye protection and a dust mask.

You can also try using a coil brush, available at most hardware and AC stores. This specialty tool has bristles that are stiffer than those of a regular broom but not as stiff as a wire brush, making them safe to use on the coils without damaging them. Be careful not to bend any of the aluminum fins that form a spiral pattern on each coil. If you do bend any of them, use a fin comb to straighten them out.

If your evaporator coils are heavily soiled, you may need to use more heavy-duty cleaning supplies and equipment than simple compressed air or a nylon brush. This will likely involve taking apart your air conditioner, cutting the refrigerant lines and possibly removing the compressor to complete the job safely and properly. If this is the case, you should consult a licensed HVAC contractor.

In addition to routine evaporator coil maintenance, you should keep grass and other vegetation cut back at least half a meter away from the outside unit to prevent the growth of shrubbery and other plants that can block the coils. You should also inspect the condensing unit for any grass clippings that have accumulated on the coils and use a lawnmower brush or similar tool to clear them. Dirty coils can reduce efficiency by up to 30 percent and will cost you money on your utility bill.