Utility bills will rise with the thermometer this summer, but you don’t have to sweat it if you gear up with the right air conditioner. Whether you've already got one or are considering buying a new one, we’ve got your go-to guide on how to save money. Just keep these things in mind.

Don’t Go Too Big

While you might be tempted to buy the largest unit available, that’s not necessarily the best strategy, says Joe Scerbo, owner of Gentec Services, based in Livermore, California.
Not only will a too-large system cost more, but it won’t work efficiently. Instead, it’ll go too hard, too fast and “short cycle,” he says, meaning it’ll go off and on too often and never reach the optimum speed and duration for the system to work most efficiently. It's similar to how the brakes in your car wear out more quickly in stop-and-go traffic than in highway driving.
Another issue is that although a large unit might cool the air, it won’t dry out the room, which is its second function. “The goal of an AC unit is to drop the temperature and remove the humidity, because that’s what makes people feel comfortable,” says Colette Ivanov, director of marketing for Sears Home Improvement Products.

Know How Much Power You Need

An AC’s cooling capacity is measured in BTUs (British thermal units) and is determined by the square footage of the area you’re trying to cool, says Ivanov.
For a 150-square-foot room, your AC should have a BTU rating of 5,000, whereas a 450-square-foot room needs a unit with a 10,000 BTU rating, she says. A central unit for a whole house is measured in tons, from a 1.5 ton unit for a 600- to 1,000-square-foot house, to a 5 ton unit for a 2,600- to 3,200-square-foot house.
If you’re still unsure, ask the store or contractor to point out the one that’ll do the job right without blowing your budget.

Buy an Energy-Efficient Unit

Look for the Energy Star certification, which means it meets the government standards for energy efficiency. “Other energy-efficient features to look for include timers so you can schedule your air conditioner to run only when you need it, and fan-only functions for use at night or on cooler days,” says Ivanov.

Plug Leaks

While most consumers may think air conditioners blow out cold air for relief, the way they really work is by removing heat from the air and leaving the cold, says Scerbo. That means it pays to have your home properly insulated so that less hot air seeps in to begin with. Also consider closing your blinds during the day, especially for windows that get lots of sun exposure.

Leave It On — Really

It’s tempting to turn your system off when you leave home in the morning and then switch it on when you return; after all, why pay to keep your furniture cool and comfortable?
But that strategy can backfire, says Scerbo, because heat can build up so drastically during the day that it takes even more energy to get it to a manageable level at night. That can be costly, especially if you live in an area that charges more during peak usage hours.

Invest in a Programmable Thermostat

Rather than strain your AC by constantly adjusting the dial, set a programmable thermostat to a higher temp at night and during work hours. The Department of Energy estimates you can save as much as 10% on your cooling costs just by turning your thermostat down seven to 10 degrees for up to eight hours a day.
If you’re feeling techy, you can invest in a smart thermostat that understands your patterns and begins to adjust automatically. Some states even offer rebates on your purchase.
Smart window ACs can also allow you to create schedules and even turn the unit on remotely via an app, says Scott Larson, manager of brand management for Kenmore, Craftsman and DieHard brands.

Conduct Routine Maintenance

Just like your car, your HVAC equipment needs regular maintenance to operate at its peak. An annual once-over is advised to check electrical connections and thermostat settings, says Ivanov.
But that doesn’t let you off the hook for routine check-ins, which should include changing your air filter at least every three months — and even monthly during heavy-use periods — as dirty filters can lead to increased energy bills and damaged systems.