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Like any appliance, air conditioners need a little TLC to deliver optimal performance. It’s the ACs that haven’t been kept in top-notch condition that tend to struggle most in hot weather.
To make sure you don’t lose your cool once the weather warms up, we asked the experts at Consumer Reports and air conditioner pros to identify the most common problems that crop up with window and central air conditioners. They highlighted eight problems to troubleshoot now. Plus, you’ll find our list of top air conditioners for small, medium, and large rooms, below.
The No. 1 problem affects both window units and central AC systems, and—we’re happy to report—it’s the easiest to fix. Here are eight questions to ask that will help you keep your AC at peak performance all summer long.
1. Is the Filter Dirty?
No matter which type of air conditioner you have, a clogged filter restricts airflow, decreasing efficiency and reducing the ability to effectively cool the air. If you haven’t cleaned the filter in your window or portable air conditioner recently, make sure you do and then check it periodically. For central AC systems, check the filter manufacturer’s recommendation for when to swap in a new one. In CR’s tests, filters last anywhere from three to 12 months.
Just keep in mind that if your system is running constantly or if you have pets, you will need to change your filters more often. “When we get calls about central air units that aren’t working well, nine times out of 10 it’s because of a dirty filter,” says Stewart Unsdorfer, owner of Central Heating & Air Conditioning in Cleveland.
Window AC Checklist
2. Is It Too Sunny Inside?
If your window AC is in a window that gets direct sunlight in the heat of the day, it’ll have to work harder to cool your space. If you have a choice, move it to a shadier spot. If not, keep your shades and curtains drawn during the day to block the sun and prevent it from heating up your house.
3. Is Warm Air Leaking In?
Check the seals around your window AC to make sure hot air isn’t getting in (or cold air isn’t seeping out). Reseal around your unit with weatherstripping if necessary.
“Most new window units come with insulation panels to place over the plastic adjustable side panels,” says Chris Regan, CR’s senior air conditioner tester. “But to maximize efficiency, you’ll still need to use weatherstripping around the perimeter of the unit. And always use the manufacturer’s installation and safety hardware.”
4. Is Your Window AC Vibrating?
Air conditioners make plenty of noise, including from the whir of the fan and the sound of the compressor cycling on and off. These noises are normal. But if you hear a vibrating noise, it may mean that your unit was installed incorrectly. Make sure it’s sitting securely in the window and review the installation instructions in your owner’s manual to confirm that no steps were missed.
Central AC Checklist
5. Is the Thermostat on the Right Setting?
With a smart or programmable thermostat, you can more easily control the temperature in your home so that it’s comfortable when you’re there and a bit warmer when you’re not. If the temperature seems off, make sure the thermostat isn’t exposed to direct sunlight, which may cause it to register the wrong temperature.
6. Are the Registers Dirty or Blocked?
If you have a forced-air heating and cooling system, regularly vacuum the registers to remove any dust buildup. Make sure that furniture and other objects aren’t blocking the airflow through your registers.
7. Are Plants Crowding the Compressor?
The outdoor compressor for central air needs adequate airflow to work correctly, so make sure there’s at least 2 to 3 feet of space between the compressor and any plants or structures. There should also be 5 feet of clearance between the top of the unit and any trees above.
8. Did You Remember the Annual Checkup?
An inspection by an HVAC (heating, ventilation, and air conditioning) technician can catch any serious problems before they get worse and leave you hot and bothered. The technician will check all the moving parts, as well as the refrigerant, and recharge the system if necessary.
Need a New AC?
If your room air conditioner is beyond repair, you can find one that did well in our tests for as little as around $200 for a small unit and upwards of $800 for a large one. Make sure you match the size of the air conditioner to the room it’s meant to cool. Below, we list models in each size that performed well in CR’s tests. You can find more in our full air conditioner ratings.
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