A/C maintenance

Window air conditioner

Clean or replace dirty filters

Vacuum off debris, then wash them in warm, soapy water; be sure filters are dry before you reinstall them. Replace a damaged filter. Clean filters once a month during the cooling season.

Vacuum coils and fins

Use an upholstery-brush attachment, taking care not to deform soft fins. If possible, remove the cover and use a soft brush or a can of compressed air on hidden dirt.

Install and seal the A/C

In a shady spot, it can run up to 10 percent more efficiently, the Department of Energy says. Be sure to seal any air leaks around the unit.

Avoid "short cycling"

Wait 5 minutes after shutting off the unit to restart it. That allows pressure in the refrigeration system to equalize, avoiding stress on the compressor.

Central air conditioning

Call a pro

Have a licensed professional change all filters; clean and flush the coils, drain pan, and drainage system; vacuum the blower compartments; and check the refrigerant and mechanical components.

Insulate ductwork

Make sure that ducts are sealed and insulated. Up to 40 percent of cooling energy can be lost when uninsulated ducts pass through uncooled spaces like attics.

Do seasonal checks

Clear debris and keep vegetation at least 2 feet away from the outdoor unit. Clean indoor grills and filters monthly.

Use a programmable thermostat

It can reduce cooling costs by up to 20 percent. And consider using a ceiling fan, so that you can set your thermostat to a higher temperature.