How to Clean Your Outside AC Unit Like an HVAC Expert

Cleaning your outdoor air conditioner unit may seem like a job for professionals, but it’s a task you can perform yourself—with considerable payoff. Not only will it help your air conditioner run and cool your home more efficiently, it will save you money in utility costs. Ultimately, regulating cleaning your outside AC unit contributes to the longevity of the appliance.

Below, our HVAC professionals break down everything you need to know about how to clean an outside AC unit. (Plus, when you should call in the experts.)

The Importance of Cleaning an Outside AC Unit

The coil around the outside component of your air conditioning system (the condensing coil) removes the heat from the air being circulated in the home. "Unlike the inside evaporator coil, there is no filter to protect the coil from the buildup of dirt, dirt, and debris," explains HVAC expert Marco Radocaj. This makes routine cleaning vital.

According to Radocaj, if the condensing coil gets too dirty, it becomes less effective at removing the unwanted heat due to restricted airflow. Eventually, this excessive heat will impact the cooling performance inside the home. This can compromise the operation of the compressor and, as a result, could call for costly repairs.

"Restricted airflow will lead to less effective heating and eventually cause premature freezing of the condensing coil, causing defrost and emergency heating to be utilized," says Radocaj, "which can be very expensive."

How Often to Clean an Outside AC Unit

You should perform this deep clean at least once a year to keep your air conditioner at peak performance, says Jacob C. Darrah, marketing director with Bill’s Heating and A/C. "Spring is the best time to do it, setting you up for a full season of effective cooling."

However, cleaning an outside AC unit more frequently may be required. Alex Tisdall, president at Pioneer Heating, Cooling & Plumbing, typically recommends cleaning twice a year, if possible. In addition to a spring cleaning, "a fall cleaning helps remove any debris accumulated during the summer, which helps prevent potential issues during the off-season," explains Tisdall.

Additionally, if you notice your energy bill increasing, your AC not cooling as effectively, or if it's visually dirty, Darrah recommends giving it another clean. (The solution may be as simple as a scrub.)

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How to Clean an Outside AC Unit

To prevent electrical hazards, turn off the power to the condensing unit either at the circuit breaker panel or near the condensing unit, says Micah Sherman, virtual HVAC expert. Once this has been done, you can proceed with the following cleaning steps.

1. Clear debris around the unit: Remove leaves, twigs, and other debris from around the unit, advises Tisdall. Then, if applicable, trim back any plants or shrubs at least two feet to allow for proper airflow.
2. Remove the top of the unit: Unscrew and carefully lift the top grille or fan off the condenser unit. “Make sure not to damage any wires connected to the fan,” Tisdall says.
3. Clean the fins: Use a soft scrub brush, old toothbrush, or coil brush to gently clean the thin metal slats lining the outside of the unit. Work from the inside out to remove dirt and debris, instructs Tisdall. Take care not to bend the fins, as they can be delicate. Do not force instruments between the fins.
4. Add water: Spray the fins with a gentle stream of water from a garden hose (or heavy-duty spray bottle) to wash away any remaining filth. "Rinse the coils from the top down, moving side-to-side, and make sure to take your time," says Sherman. "You should be able to observe the water coming out from the other side of the fins." Avoid using a pressure washer, as it can damage the unit. 
5. Air-dry and reassemble: Allow the unit to air-dry. Once everything is clean and dry, reattach the top and reconnect to power.
   

When to Call an HVAC Professional

Sometimes, an air conditioner will exceed the typical homeowner's ability to clean. “Examples of this are pet urine deteriorating coils, objects hitting the unit and flattening the coil fins, or pet hair clogging the coil too deeply to clean it yourself,” says Darrah. “Your local HVAC professional has access to strong chemical cleaners, as well as tools like fin combs to repair coil integrity.”

If you’ve cleaned your unit but still notice poor airflow, strange noises, or reduced cooling, Tisdall says it might signal a deeper issue like refrigerant problems or internal damage. This needs a trained technician’s expertise.

"Visible damage such as bent fins, refrigerant leaks, or corrosion should never be ignored," says Tisdall, nor should a unit that turns on and off frequently. "That could point to a malfunction that a professional should diagnose."