Air conditioners are a lifeline come the dog days of summer, when soaring temperatures make a well-cooled home a welcome respite from the outdoors. Maintaining an AC unit ensures it will be there to keep everyone cool when the mercury rises. The following are some steps homeowners can take to keep their AC units in tip-top shape this summer.

• Replace the air filter on the unit. Dirt, dust, debris, and pollen can quickly fill the filter on an AC unit.

• Schedule annual maintenance on the unit. Routine maintenance performed by a local HVAC technician is another way to ensure an AC unit is running at peak capacity when it’s most needed. Annual maintenance appointments also give HVAC professionals a chance to assess a system compared to the previous year, which can help them identify if a unit is nearing its end.

• Help the unit make it through the summer. Whether it’s a typical summer or one marked by a handful of heat waves, AC units can use a little help to get through the season. Closing curtains throughout the house on hot afternoons is a natural way to keep a home cool during a heat wave, and that can cut back on home cooling costs and protect a unit from being overworked. Ceiling fans also can be installed to keep rooms cool and circulate air.

• Use a programmable thermostat. Programmable thermostats allow homeowners to set the temperatures inside their homes throughout the day. If no one is home during the afternoon, there’s no reason to have the AC cranking. Program the thermostat so the house is comfortable when people are home, but raise the desired temperature when no one is around. That gives the AC unit a break during the day and can help to dramatically reduce the cost of cooling the home.