How to Clean an Air Conditioner

A filthy fan or air conditioner is not only less efficient at cooling you down, it’s also a potential health risk, especially if you have sensitive lungs or allergies.

“If you don’t maintain them well, and everything you breathe is filtering through this gigantic sheet of dust, that’s not very helpful,” Dr. Richard Lebowitz, a rhinologist in New York City, told The New York Times in 2017.

So don’t wait to clean your fan or AC until next summer, when the sweltering heat is overbearing. Instead, clean it now, before you store your AC or fan for the cooler months. If you live in warm climates year-round, you should clean your AC or fan at least once a month.

Set aside half an hour, although time may vary depending on the kind of fan or AC you own. You may also need to add some extra time to allow the components to dry.

If you still have the instructions, they may offer you some guidance; here are the cleaning instructions (PDF) for our favorite room fan.

Examine the fan to locate the seams between the plastic parts. Remove any screws holding them together; then wedge your knife or flat-head screwdriver into the seam and gently pry the two halves apart. They should pop right open. Try to avoid touching the casing around the motor itself, so you don’t have to mess with any electronics.

If there is a lot of buildup, you’ll need to use a vacuum to remove the thick layer of dust on the blades.

After you’ve taken care of the big, obvious stuff, scrub the blades using hot water. Depending on how gnarly they are, you may want to add vinegar or soap to the water. And you can really get at grime with a toothbrush or sponge. Otherwise, a wet rag should do the trick.

Once the fan blades are clean, repeat to remove any dust on the outer case or grille.

One thing to note: the PDF instructions for the Vornado 630 (our top pick) instructs readers to remove the fan blades from the motor shaft before cleaning. But several Wirecutter staffers found from personal experience that the blades wouldn’t budge. Instead of trying to remove the blades, you can simply clean the backs while they remain attached, just as we explain above, and it should be fine.

All the pieces need to dry out completely before you reassemble the fan. To be safe, let them dry for at least an hour. Afterward, put the fan back together.

Note: Tower fans are notoriously difficult to take apart or clean, and this is a large part of why we don’t recommend them. In order to thoroughly clean our former Seville pick, you had to dismantle nearly every part of the fan and clean each tiny hole with a cotton swab.

Whether you have a window AC or central air, it should have some kind of filter. And it’s incredibly important that you clean or replace the filter according to the instructions.

Most window air conditioners have a reusable filter. The filter blocks dust from getting into the important parts of the system. It’s sort of like the lint filter on a clothes dryer—it’s usually easy to remove, sliding out from the front of the unit.

You should take the filter out at least once a month to clean it, “or it can lead to both poor performance and biological growth,” says Gary Woodruff, sales and marketing manager at HD Air. Most modern units (including all the models we tested) have a light that will remind you to do this after every 250 hours of use. Most WiFi-connected ACs will send you a cleaning reminder through the app as well.

Woodruff recommends vacuuming your filter, and then rinsing it off with hot water and leaving it to dry. “A mild detergent should be fine as well,” he says. “But I’d be cautious on something acidic like vinegar unless it was in the manufacturer’s instructions,” Woodruff adds.

While your filter is drying, empty the condensation from the base of your air conditioner (you may need someone to help you do this, especially with a Portable unit). Some models come with a drainage plug, but otherwise, simply tilt the AC toward the back and pour out the water. This is particularly important to do before you put your AC back into storage for the winter.

Trust me, you don’t want to get a face full of unfiltered dust.

Most central air systems use 1-inch, medium-efficiency MERV filters, such as the Nordic Pure MERV 12. Depending on the specifics of your home (and pets), you should replace these every one to three months. “If the filter looks dirty, it is dirty,” Woodrow says. “The smallest particles get pulled into the filter, causing it to turn gray or brown, so it’s possible that it’s time to replace the filter even if it’s not covered with dust on the surface.”

If you want your filter to last a little longer, you could try vacuuming off any obvious debris (read: pet hair) that’s collected on the surface, but don’t try to push it. A dirty filter will make your system less efficient, which means it’ll cost more to run. So it’s worth spending the money for a regular replacement.

If you have a 4- to 6-inch-wide high-efficiency media air filter, you should check on it every six months, even though it could last up to a year. Check with your service person to figure out the specifics of your system. If you have a smart thermostat, some are able to remind you when it’s time for a replacement filter.

Your old filter is going to be full of dust, so make sure you dispose of it right away. It’s a good idea to wrap it in its own plastic trash bag and tie it off immediately, so the dust doesn’t escape. Our favorite filters are made of recycled (and recyclable) beverage board paper, but check your local ordinances and the filter materials before you dispose of the filter.

Most filters are marked with a directional arrow that shows you which way the air should be flowing. Make sure this matches up with your equipment. Otherwise, all that dust and debris—and maybe even the filter itself—will get sucked into the system.

You should also check that the filter fits snugly into the slot. Even if the filter is the right width, it may not be the correct length. And that can be a problem.

“If air can get around the filter, so can dust and debris,” Woodruff explains. If this happens—or if your filter is loose for some other reason—you can try to seal the gaps with duct tape, or ask your HVAC service provider if they can add a cover to keep the system air-tight.

Changing the filter is crucial, but regular maintenance will help your central air system live a long and healthy life. A routine checkup by a professional serviceperson will ensure that your system is working at maximum efficiency, and it will catch any problems that might make things worse over time. Newer systems may need less attention; older systems may need more. Find a local company you can trust, and let it be your guide.

Thom Dunn

Thom Dunn is an associate staff writer at Wirecutter reporting on HVAC and other home improvement topics. Sometimes his curiosity gets the best of him, such as when he plugged a space heater and a Marshall guitar amp into the same power strip. Pro tip: Don’t do that.

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