The Right Way to Clean an Air Conditioner's Outdoor Coil

Most people are familiar with their air conditioner's outdoor coil because it's a component they can see. While the indoor coil often resides within the confines of a basement, crawlspace, or attic, the outdoor coil is outside and on full display to the world.

And being exposed means the outdoor coil gets dirty.

Nearly all HVAC companies say they'll clean your outdoor coil as part of a seasonal maintenance agreement, and most of those companies do a pretty good job. However, some of them fail to clean the coil properly. They just spray down your outdoor unit with a hose and call it done. Unfortunately, that's not the right way to clean an air conditioner's outdoor coil. Far from it.

Dirty outdoor coils cause problems.

Before we go over the right way to clean an outdoor coil, aka the condenser coil, let's consider why you care about cleaning it in the first place.

The condenser coil is connected to a refrigerant line set, which is the copper tubing that runs between the indoor and outdoor components of your AC. When the air conditioner runs, it transfers heat from your home to the refrigerant inside the evaporator coil. The warmer refrigerant circulates through the line set to the condenser coil (outside), where the heat is deposited into the surrounding air. The result: a cool and comfortable home.

Over time, dirt, pollen, and other outdoor grime builds up on the condenser coil. If you don't clean that stuff off, the system can't effectively remove heat from your home, resulting in:

  • Discomfort: Your AC might not cool your home effectively, leaving you uncomfortable during the hottest months of the year.
  • Expense: Since your AC has to work harder to satisfy your thermostat setting, it will run more frequently and use more energy. It won't live up to its SEER rating.
  • Breakdowns: An overworked AC is prone to equipment failure. Parts fail more frequently when an air conditioner is working harder than it's designed to work.

The solution to this problem is simple: prevention. Just have the coil cleaned every year!

Here's the right way to clean an outdoor coil

These are the steps our technicians take to make your AC's outdoor coil clean and sparkly:

  1. Turn off power to the unit. We often have to temporarily move or remove components to provide a proper cleaning, so turning off the power is essential.
  2. Check the refrigerant pressure. In many cases, the pressure will be higher than it's supposed to be for a given size and type of air conditioner. We always record the pressure before cleaning the coil.
  3. Remove the outer casing. You can't just spray down the outside of an outdoor unit and call it a day. You have to actually take the casing off to access the coil.
  4. Rinse the coil down with water. Self-explanatory. We get a hose and spray water directly onto the coil.
  5. Spray the coil with cleaning chemicals. There are special, manufacturer-approved cleaning chemicals designed just for air conditioner coils. After rinsing the coil, we spray it with the appropriate cleaning solution. If you have a Trane air conditioner with an aluminum Spine Fin™ coil, there's a special cleaning chemical just for that type of AC.
  6. Re-rinse the coil with water. This final rinse removes the cleaning solution, resulting in a clean-looking outdoor coil.
  7. Remove all debris from inside the outdoor unit. Sticks, leaves, and straw often accumulate within your outdoor unit. Removing them can improve AC efficiency and help prevent the coil from getting dirty again right away.
  8. Check the refrigerant pressure again. Most of the time, a coil with high pressure will now have lower pressure in line with factory specifications. That means the cleaning was effective and the AC will run more efficiently.

That's it! It's actually a straightforward process that every HVAC company should be able to do right. The resulting gains in comfort and efficiency are often dramatic, so don't let your coil go a whole season without a cleaning.

At PV, an annual coil cleaning is included as part of our service agreement. In addition to the other preventative maintenance tasks our team performs, we clean your outdoor coil and verify the refrigerant pressures in your system to ensure optimal performance.