A Clean AC is a Cold AC: Cleaning Air Conditioner Coils

There is one quick and easy way to make sure your air conditioning system is operating more efficiently this summer, and it’s often overlooked by both homeowners and people who maintain commercial buildings. Keeping your central HVAC system clean inside and out is essential for proper operation — and if you don’t bother, you’re looking for trouble.

Why is cleaning your coil important?

First, there is the matter of your condenser coil. In the normal operation of a traditional split (indoor/outdoor) air conditioning system, heat from the house is sucked through the air returns, absorbed by the refrigerant passing through the system, then dissipated into the air via the condenser, which lives in your outdoor unit. Think of it like the radiator in your car, which channels heat from the engine block into a labyrinth of fluid-filled passages over which air is blown to achieve cooling. If your radiator gets too dirty, your car will overheat, as there is no way for the engine heat to move into the ambient air with the dirt acting as an insulator.

Allowing the external unit at your home or shop to get dusty has the same effect. A layer of dust only 1/100th of an inch thick on your air conditioner’s condenser coil reduces efficiency by five percent.

Additionally, allowing the vents inside your home to accumulate dust causes its own set of problems, restricting airflow and drastically reducing the indoor air quality of your building. The average US house is faced with an accumulation of 40 pounds of dust every year(!) and clogs your ventilation system from one end to another.

With dirty coils on the outside and/or dirty vents inside, your system must work harder to meet demand, placing it under additional strain and wasting energy — both costly long-term side effects. You may experience diminished levels of refrigerant, ice formation on the evaporator coils (inside the house), and an overheated compressor. Not to mention the fact that a grimy system cannot effectively remove humidity, which not only makes your inside climate less comfortable, but also fosters the growth of mold, mildew and certain bacteria and viruses.

How do I keep my AC system clean?

Let’s take a look first at your condenser coil, located in your outdoor AC unit. The fact that this sits outside every day of the year puts it in constant direct contact with unforgiving weather, environmental pollution, random debris and invasive plant growth. Units installed at ground level, especially those situated near streets, alleys, restaurant exhaust vents, etc., are at the highest risk, as they are most likely to be coated in grime, soot and dust. This coating severely inhibits proper heat transfer, and even worse can cause physical damage to your coil, as sulfur and other chemical compounds in airborne grime have a corrosive effect. The air outside may literally eat holes in your coils, causing potential refrigerant leaks and even complete system failure!

To clean your outdoor unit, you’ll need, at the very least, a garden hose with a sprayer. For particularly dirty applications, you may wish to use a commercially available condenser coil cleaning product, which you can get at most local hardware stores. Basically, all that is required is to spray off any accumulated gunk that may be clogging the many fins that act as a heat sink, dissipating the heat from inside your house to the ambient environment. Take care not to bend or damage these fins, and note if you see many of them appear to be mashed. If a significant number of them have been flattened, you may want to contact your HVAC professional to come out and inspect the unit; these cooling fins can be “combed” out to restore much of their heat transfer ability.

Older units are especially susceptible to environmental corrosion, so take extra care to make sure these are kept clean and inspected for damage. Also be sure to trim all vegetation back to at least a two-foot radius around the edge of the entire unit. Allowing trees, grass, weeds and other natural growth to creep up around it will seriously reduce the ability of the unit to dissipate heat into the air. The same obviously goes for trash, debris, leaves, grass clippings and anything else that accumulates around it.

To keep the vents inside your home or office clean, make sure you change your air return filter frequently, especially if you live in a dusty environment, or have pets. As a rule of thumb, an average home with no indoor pets should replace this filter every 90 days; with one dog or cat, shorten that period to 60 days. If there are two or more pets in the house, and/or anyone within the home suffers environmental allergies, change the filter every 20 to 45 days. This will make sure your indoor air quality is satisfactory and keep your vents cleaner, too. If you suspect your vents are already subject to a buildup of dust and other airborne particulate, call your HVAC experts for an inspection. They may recommend a commercial vent cleaning.

On the whole, your HVAC system should be inspected, and the coils cleaned twice a year to ensure safe, efficient, low-cost operation and to solve any potential problems, before they become much more complicated and expensive.