1. Maintain it. Have an air conditioning technician come to your home every spring before it gets too hot and check your system out. The earlier you catch a problem and repair it, the smaller than problem will remain.
2. Add insulation to your attic or crawlspace so hot air doesn’t get in the house. The warmer the home’s air, the harder the air conditioner has to work. The harder it works, the quicker it will wear out.
3. Make sure your unit is the right size. Bigger isn’t necessarily better when it comes to a/c. A room air conditioner that’s too big for the room it’s supposed to cool won’t operate as efficiently as a smaller one that’s the right size.
4. Install a whole-house fan. It will keep your home cool without using the air conditioner on days when the sun’s not too hot or overnight when the outside air is cooler than the inside air.
5. Install ceiling fans, or if you have them already, turn them on. Ceiling fans move the air so you’ll feel cooler, which will let you raise your thermostat a few degrees without noticing any difference in your comfort.
6. Keep lamps and TV sets away from your air conditioning thermostat. The thermostat can “feel” the heat from appliances and will respond by running longer than necessary.
7. Install a programmable thermostat and set it to automatically raise the thermostat a few degrees when you leave for work in the morning and again when you go to bed at night. You can also set it to cool the house before you get home from work or wake up in the morning.
8. Plant shrubs near your outdoor air conditioning unit to shade it. If you do, it will use up to 10 percent less electricity. A tip: Don’t plant so close to the unit that the shrubs block its air flow.
9. Block the sun from shining through windows and making your room hot. Install sun screens or apply sun-blocking film on east- and west-facing windows, and close drapes or blinds on hot, sunny days.
10. Replace your air conditioner filter every month. Switch to a one-inch pleated filter, which costs around $5 and will keep more dust and dirt away from your air conditioning unit than a cheaper, flat filter.
11. Replace incandescent light bulbs with compact fluorescent bulbs. Incandescents give off more heat than light, and that can make your room feel warmer. CFLs are cool to the touch, use 75 percent less energy and last 10 times longer than incandescent bulbs.