Getting a new air conditioner? Here’s what to know:

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CHARLOTTE — With summer heat setting in, a lot of people are cranking up the air conditioning, or shopping for a new unit. But if you choose wrong, you can end up paying more than you need to, and still feel the heat.

Consumer Reports tested air conditioners in extreme conditions - and has advice to help you cool your home efficiently all summer long.

Arianna Coger spent the winter months sweating it out in the Consumer Reports air conditioner test lab – designed to mimic a hot, sticky summer day.

“It’s like 90 degrees right now and we try to see how long it takes for this air conditioner to bring it down to 75,” Coger said.

Consumer Reports advises that if you want to help your AC run better, vacuum and wash the filter. Gently vacuum the condenser coils, and keep the outside area free of leaves, dirt, and debris. You’ll want to do that once a month during the summer.

And when it’s time to buy a new AC, match it to the room size. A unit that’s too small may not cool the space. One that’s too large can cycle on and off too quickly, leaving the room humid and wasting energy.

But if you’re tired of installing and removing window units every year, there is another option.

“Mini-splits are a good option if you lack the ductwork for central air conditioning,” said Yasmeen Khan with Consumer Reports

Mini-splits have an outdoor unit, and one or more indoor wall-mounted units. They’re more expensive, but Consumer Reports says they tend to work well.

Khan says mini splits can cool large spaces. They’re very efficient, too, sometimes more than central AC.

An air conditioning unit has to work harder if it’s installed in a window that gets direct sunlight.

If you’re able, move it to a shadier spot, or keep your shades and curtains closed to block the sun.