To keep your air conditioner running efficiently, you'll need to maintain it properly. Experts agree that keeping the air filter clean is the most important thing you can do to maintain an efficient unit. If the filter becomes clogged with dust and dirt, it can block the flow of air, increasing your energy use and possibly damaging the air conditioner.
During the cooling season, check all filters monthly and clean or change them as needed. It's also important to ensure the unit itself isn't blocked by debris; you should maintain a clear, 2-foot perimeter around the unit. You can also spray the condenser coils with a garden hose once a year to clear away twigs, leaves and dirt. Clean the vents as well, and wipe the unit down with a damp cloth.
Experts also recommend calling in a service professional regularly to give your central air conditioner a tune-up. Energy Star suggests doing this once a year -- preferably in the spring, before the cooling season starts. At SmarterHouse.org, a site run by the American Council for an Energy-Efficient Economy, the guidance is that every two to three years should be sufficient. During the service visit, the technician should change all the filters, vacuum the blower compartments, clean and flush the coils, and drain the pan and drainage system. After cleaning, the tech should check to make sure all parts are working properly: This will include checking electrical connections, lubricating all moving parts and checking airflow over the indoor coil. Keeping the airflow at the right level can boost the air conditioner's efficiency by anywhere from 5 to 15 percent.
Another job the technician may need to do is check the refrigerant level. The experts at SmarterHouse.org say that "A pre-2006 system that is 20% undercharged can operate at 20% lower efficiency, and field studies show that the majority of older central air conditioners are undercharged enough to affect performance somewhat." On the other side of the coin, have a system that's overcharged can not only reduce efficiency and, but could also reduce its lifespan.
In the past, most air conditioners used a refrigerant called R-22, or Freon. However, this chemical turned out to be harmful to the ozone layer, so air conditioners made after 2010 no longer use it. Most new air conditioners use a refrigerant called R-410A. However, Freon is still available for recharging older systems that use it. Regardless of the refrigerant, however, federal law requires that it be recycled by an EPA-certified technician.
Because checkups are a regular necessity, ConsumerReports.org suggests that "A service plan that combines regular inspections with discounts on repairs and a labor warranty" could be worthwhile -- a departure from its typical recommendations regarding service plans. They suggest negotiating with your contractor to have that included in the overall price of the system. The editors of FurnaceCompare.com note that many contractors are willing, if not eager, to do that -- both for the benefit of future referrals and to help close a deal.
What if you follow all these steps and the air conditioner still breaks down? FurnaceCompare.com says there are several possible causes that you may be able to fix on your own. First, check the thermostat -- It may simply need new batteries or perhaps the switch wasn't pushed all the way to the "cool" position. If that's not it, check the fan blades, which are usually right underneath the unit's case. They may need to be cleaned or tightened. You can also check your fuse box or circuit box to see if a tripped circuit is keeping the air conditioner from getting power.
Also, if the unit won't turn on at all with the temperature set very low, feel the copper lines that lead from the condenser. If the larger line feels warm, you may be out of coolant; if it's frozen, the line may be clogged. Shutting down the system and waiting for it to thaw may fix the problem. If that doesn't help, then it's time to call a professional.