We may earn revenue from the products available on this page and participate in affiliate programs. Learn More ›
These days, more than 90 percent of homes and virtually all businesses in America use air conditioning to beat the summertime heat. In fact, according to the U.S. Department of Energy, air conditioners use about 6 percent of all the electricity produced in the country. Given the overwhelming prevalence of AC, most people think they know how to maintain their system properly, whether it’s central air, a window unit, or ductless mini-splits. Many homeowners fall victim to common mistakes that waste energy, shorten the working lifespan of their air conditioner, and cost money.
1. Buying the Wrong Size System
Always use an air conditioner that’s the right size for your home. An oversized unit may cycle on and off too quickly, making it ineffective at removing humidity and maintaining uniform temperatures. On the other hand, a too-small unit will need to run constantly, which will drastically shorten its lifespan. Determine your needed cooling capacity by doing a load calculation, taking into account each room’s square footage, layout, insulation, function, and typical occupancy.
2. Cooling an Empty House
Because cooling an empty house wastes both money and energy, it’s a good idea to upgrade to a programmable home thermostat. This technology allows you to raise and lower the temperature of your air conditioner based on a preset schedule, which can save hundreds of dollars annually. Boost your energy efficiency even more by keeping closet and cabinet doors shut so excess air doesn’t get in.
Best Smart Thermostat
Google Nest Gen 4
The Google Nest Gen 4 is easy to install and use, and optimizes performance without constant input. Read the review.
See It
3. Poor Position of the Thermostat and Vents
Inside your home, make sure the thermostat is properly positioned and vents allow for proper air circulation. Place the thermostat away from direct sunlight and heat-producing lights and appliances so you do not get inaccurate readings, and cause the air conditioner to work overtime. Do what you can to make sure that AC vents are not blocked by plants, furniture, or curtains.
4. Not Using Fans to Circulate Cool Air
If possible, combine your air conditioning with the use of strategically placed fans. Any type of fan helps cool the air circulating throughout your home, which will make you feel more comfortable at a higher indoor temperature. Be sure to set ceiling fans to run counterclockwise during the summer in order to push the air downward. Note that you should also minimize the use of exhaust fans in the bathroom and kitchen while you’re running the AC, as these remove cool air from your home.
5. Leaving Your Windows Open When the AC is on
Open windows and doors and windows invite humidity inside your home and let chilled air escape. Your air conditioner must then work extra hard to compensate, wasting vast amounts of energy along the way. Always keep doors and windows closed when the AC is running.
6. Forgetting to Clean the Filter
Clean or replace HVAC air filters every month during the cooling season, and more frequently if the filter seems excessively clogged with dust and debris. A clean AC filter significantly improves an air conditioner’s efficiency, lowering your energy consumption by 5 to 15 percent. On central air conditioners, filters are typically located on the return ducts in walls or ceilings. Room air conditioners have a filter mounted in the front-facing grille, while ductless mini-splits house their reusable filters in a removable panel. Consult your owner’s manual for exact instructions on changing the air filter.
7. Allowing Debris to Pile up Around the Condenser
Outdoor condenser and evaporator coils can become clogged with dirt, which blocks airflow and insulates the coils, reducing their ability to manage heat efficiently. To keep the coils from clogging, don’t place your AC components near dryer vents, and remove fallen leaves, grass clippings, and other outdoor debris regularly. Trim shrubs and other foliage to give at least 2 feet of space around the condenser, allowing for adequate airflow. Our guide to cleaning air conditioning coils can help you keep your condenser in tip-top shape.
8. Not Attending to Routine Maintenance
Properly maintaining your air-conditioning equipment will maximize its operating efficiency and effective lifespan. At the beginning of the cooling season, inspect the seals on the air conditioner as well as the seals between the unit and the house to ensure no cool air is escaping. Then, check the fuses, circuit breakers, wire, and terminals for corrosion; clean the condensate drain line; and examine fans and other moving parts for signs of wear.
9. Putting the AC Unit in Direct Sunlight
Although air conditioners aren’t the most attractive items in a landscape, homeowners shouldn’t try to “hide” their unit in an inopportune spot. The location of an air conditioner has a big impact on its energy efficiency. Try installing it in a shady spot on the east or north side of your house, because too much direct sunlight will make the system work harder. Additionally, don’t place concealing shrubs or plants too close to the unit, as these will impede ventilation and may clog the condenser coils.
10. Not Calling an HVAC Professional When You Need One
Some air-conditioning systems issues, such as refrigerant leaks, can only be diagnosed and repaired by a qualified HVAC technician. Have an HVAC professional inspect and tune up your system on a regular schedule, ideally annually. A routine service call is going to be far cheaper than the cost of an AC repair emergency.
