One of the easiest ways to keep your central air conditioner running smoothly is to keep its various parts clean. The condenser unit (outside) and the evaporator coil (inside) work harmoniously to move warm air from your home outside and produce cool air within. If one or both of them are dirty or clogged, air flow is diminished, efficiency is reduced, and you and your wallet suffer. Keeping these and other parts—including the air filter and drain line--clean and clear of debris will go a long way toward maintaining the overall system’s smooth function during the time you need it most.
The condenser is the part of your air conditioner that is located outside your home. Its job is to circulate coolant through the A-coil and expel the heat it absorbs outside. Over time, the fins on the condenser unit become clogged with debris, including dirt, dead leaves, grass clippings, and various other plant matter that the fan manages to suck in. This debris makes it harder for the condenser to release heat and places a strain on its various components. When the fan draws air in through debris-clogged fins, the unit suffers from reduced efficiency and is more subject to breakdowns. Additionally, the debris hinders air flow and can cause the unit to not cool properly.
The evaporator coil, or A-coil, is usually located above the furnace in the plenum. Its job is to absorb heat from the home’s indoor air and transfer it, via refrigerant, to the outside condenser for release. Though the evaporator coil does not play a role in heating your home, the air heated by your furnace in the winter months passes through it before entering the supply ducts. In fact, all of the air that moves through the HVAC system passes through this coil. More exposure to air flow, of course, means more exposure to dust and debris. Over time, dirt contained in the moving air collects on the surface of the coil, acting as an insulator and inhibiting heat absorption. A dirty evaporator coil inhibits not only cooling your home in the summer but heating it in the winter as well, because of diminished air flow.
The Air Filter
The air filter (aka furnace filter or air conditioner filter) is usually located in the return duct, before the blower compartment. Though the common perception is that the main role of the air filter is to prevent dust from entering your living space, its primary purpose is to prevent dust from entering the fan compartment and dirtying the evaporator coil. Because the evaporator coil requires unhindered air flow to work its magic (heat absorption, if you missed it above), even the smallest amount of dirt will reduce efficiency. Equal in importance to maintaining your air filter is ensuring there are not any "filter bypass" issues, when an ill-fitting or improperly installed filter allows air to sneak around it and head straight for the fan and A-coil.
The Condensate Drain Line
The AC condensate drain line, usually made of PVC or rubber hose, drains excess moisture produced by the evaporator coil and transports it to a drain often located somewhere near the furnace or to a condensation pump. This line over time becomes plugged with dirt, algae, and mold. Water pooling around the furnace is often the first indication of a plugged drain line. Keeping your condensate drain line free of blockages is crucial to the proper functioning of your AC.
Hiring a Professional
DIY tutorials abound on how to clean each of these parts, and a determined homeowner with sufficient time and suitable tools would achieve some measure of success. However, the A-Coil, which is arguably the most important component to keep clean, is also the most difficult to clean (and sometimes inaccessible). Further, having your system professionally cleaned would allow the HVAC technician to check for proper air flow and look for filter bypass issues, check system components, and verify that refrigerant levels are where they should be, adding more if necessary.
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Many thanks to our technician Roy S for lending his expertise to this article.