Is It Time to Get a New Window Air Conditioner?

AC units don't last forever. Here's how to determine when you need a new one.

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detail of exterior of brick apartment building with multiple old window air conditioner units Photo: Bruce Yuanyue Bi/Getty Images

A great window air conditioner can keep a room cool and comfortable throughout the day, even during a summer scorcher. It can also last a long time before it has to be replaced.

Generally, window air conditioners last about eight to 10 years. Some units, however, may have a shorter or longer life span, depending on how well they’re maintained and the quality of the unit.

More on Air Conditioning

If your window air conditioner is on the fritz—for example, it’s struggling to produce cooler air—there are a few steps you should take to evaluate it before you retire it for good.

First, inspect the seal around the unit to make sure warm air isn’t getting into the room or cold air isn’t escaping. If leaks are present, reseal the unit with weather stripping.

Next, remove the filter (usually located just behind the grill) and clean it with warm, soapy water; over time it can get clogged with dirt and dust, which reduces airflow through the unit, diminishing its efficiency and ability to clean the air. While the filter dries, check the now-visible evaporator coils. If they’re covered in dust, clean them with your vacuum’s upholstery brush, taking care not to bend the fragile fins.

“If the air coming from the unit is warm, you may have a problem with the compressor or the level of refrigerant, and should replace your window air conditioner if it’s out of warranty,” says Chris Regan, who manages CR’s air conditioner testing. Warranties usually last between one and five years.

Ready for a New Window Air Conditioner?

If it’s time to buy a new window air conditioner, Consumer Reports can help you hone your search. We tested more than 40 window air conditioners in our labs.

After installing a unit in a double-hung window in our climate-controlled testing chamber, we crank up the air temperature to 90° F, then measure how long it takes the AC to cool the room by 10° F. The best units hit the mark in less than 15 minutes. We also gauge how accurately the AC reaches its set temperature, whether it can recover from a simulated brownout, the intuitiveness of the controls, and how loud each unit is when running on low and high.

CR members can read on for our top pick for three room sizes, based on our latest tests. You can check out even more choices in our complete air conditioner ratings. And for more information on your options as well as shopping tips, see our air conditioner buying guide, which covers portable and split ductless air conditioners, too.

Best Window AC for a Small Room

(100 to 250 square feet)
For a small bedroom, home office, or guest room, look for an air conditioner with a capacity of 5,000 to 6,500 Btu. You’ll want one with good scores for comfort and noise. Here is our top choice.

Best Window AC for a Midsized Room

(250 to 350 square feet)
To cool a bigger or busier room, you’ll want to step up to a midsized air conditioner rated 7,000 to 8,500 Btu. If it’s for a bedroom, heed our noise scores. Here is our top recommendation.

Best Window AC for a Large Room

(350 to 550 square feet)
For a living room or family room, you’ll want a large air conditioner, 9,800 to 12,500 Btu, especially if you have an open floor plan. Here is our best pick.

Headshot of freelance writer Daniel Bortz

Daniel Bortz

Daniel Bortz is a freelance writer in Arlington, Va. His work has been published by The New York Times, The Washington Post, Newsweek, Money magazine, and Kiplinger's, among others.