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Get up to $2000 tax credit on select AC systems! Call now to learn more.

Get up to $2000 tax credit on select AC systems! Call now to learn more.

Why Does My Home’s Air Filter Get Dirty So Quickly?

A clean air filter (left) next to a dirty air filter (right)

It’s a pain.

Your air conditioner filter keeps clogging up too quickly, so you have to keep changing it and changing it and changing it.

Why is this happening?

Could be any number of things. Let’s explain each potential cause and what you can do to fix them.

Cause #1: You’re using a 1-inch pleated air filter

One-inch pleated filters quickly get dirty because they’re designed to catch more airborne contaminants.

Think of 1-inch pleated air filters as a fine fish net with a very small gaps: it catches everything from big to small fish, but that also means the net fills up with fish faster (say that 3 times fast).

Solution: Switch to a cheap disposable fiberglass filter or thicker pleated filters. If you’re serious about improving your home’s indoor air quality, consider installing an air cleaner instead.

Cause #2: Your AC’s fan is set to “ON”

When the thermostat’s fan setting is set to “ON” the indoor blower will run 24/7, constantly circulating air over the air filter. So now the filter is constantly catching airborne contaminants, causing it to quickly get dirty.

Furthermore, your energy bills are higher because running a blower nonstop isn't cheap.

Solution: Check your thermostat fan setting and make sure it’s set to “AUTO.” Now the blower should only run when your system is heating or cooling the air.

Cause #3: Leaky air ducts

Leaks in the return ductwork pull in dust from unconditioned spaces—like an attic or crawl space— and quickly clog the filter, especially if your filter is located near your ACs inside unit, like in this picture:

Duct leaks also run up your energy bills month after month.

According to ENERGY STAR, “In a typical house, however, about 20 to 30 percent of the air that moves through the duct system is lost due to leaks, holes, and poorly connected ducts. The result is higher utility bills and difficulty keeping the house comfortable, no matter how the thermostat is set.”

Solution: Get an HVAC contractor to investigate your air ducts for leaks and seal them if needed.

Cause #4: You have furry pets

Got cats and/or dogs? Pet hair and dander will quickly clog up your filter in no time.

Solution: Get rid of your pets. Kidding. Consider getting a more advanced air filtration system.

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