Is your air conditioner not blowing cold air?

Most homeowners rely on their HVAC system to keep them cool in the summer. If you notice your air conditioner isn’t producing cool air, don’t stress. It doesn’t necessarily mean you’ll need to buy an entirely brand new unit. There are a number of different possible causes, such as a refrigerant leak. However, can it be as simple as a dirty air filter?

We answer everything you need to know about whether a dirty air filter can cause your AC system not to cool.

Can a Dirty Filter Cause AC Not to Cool?

Yes. A dirty air filter can indeed cause your AC not to cool. In fact, it’s one of the main reasons your AC isn’t cold, although there are other possible causes, too. Luckily, it’s also one of the easiest problems to resolve.

The air filter catches debris and dust in the air, keeping the air in your home as clean as possible. However, when the filter gets dirty and clogged, it impedes proper air flow.

If air can’t move properly, the cold air gets trapped inside of the unit. The cold air won’t escape out of the unit.

Instead of cold air, you will likely experience limited airflow or warm air.

A dirty air filter can force your HVAC system to work overtime, using more energy to cool your home. The excess stress can also force components, such as the fan, to work overtime. If the fan must work overtime, it will deteriorate more quickly, leading to expensive repairs and a diminished lifespan. Finally, after time, the cold air trapped in the AC will eventually freeze the evaporator coil, and a frozen air conditioner coil can damage the unit completely.

Signs of a Dirty Air COnditioner Filter

Low Efficiency

Did you notice your utility bills increase drastically since last year? A high utility bill during the summer months can indicate an overworked central air conditioner.

Compare your bill to your bill from the same month last year to see if there’s a significant discrepancy.

Poor Indoor Air Quality

Do you notice more respiratory irritation in you and the other members of your family? Can you just feel that the air is heavier and tastes worse?

Check your home’s air quality (you can buy tests you can perform yourself or hire a professional HVAC company to test the air for you), especially if you have people with asthma and other respiratory issues in the home.

If the air quality comes back as poor or even hazardous, turn off your unit until you replace the filter.

After you turn off the air conditioner, veniltate by opening windows and utilizing clean fans. You can also invest in an air filter.

No Recent Maintenance

Some people go years without performing any maintenance on their air conditioner because it’s new or they don’t just treat it like a piece of furniture. 

If you can’t think of the last time you got air conditioning service, even if it’s new, you should consider that a sign of a dirty air filter.

On average, you should clean your air filter ever 1 – 3 months (even more often in summer and winter).

Why Did My Air Filter Become Dirty?

All AC air filters become dirty over time, no matter how clean you keep your home and no presence of pets.

Pet dander, cigarette smoke, and toxins from chemicals will expedite the process.

Some people choose to block their HVAC system’s cold air return in an effort to keep the air from getting back into the system in the first place, but this is a mistake.

Cold air returns are an integral part of the heating and cooling process. It takes it existing air to filter it and then expel it at the appropriate temperature. By the way, make sure you don’t block cold air returns!

You won’t make your unit more efficient (quite the opposite), and your air won’t be any cleaner.

How to Clean a Dirty Air Filter

While potentially intimidating to people with limited home maintenance skills, you can feel confident cleaning your AC air filter yourself. Eventually, it’ll become second nature to you.

Follow these simple steps to clean a standard air filter (keep in mind that your unit may vary slightly, so refer to your user manual if these steps don’t apply to you). \

Step One: Turn Unit Off

Turn off the unit to avoid damage to the unit while you clean the filter.

Step Two: Locate and Remove Air Filter

Locate the filter (usually easily accessible in the front or on the side of the unit). Remove the filter.

Step Three: Clean or Replace Air Filter

It’s best to change filters. However, if you don’t have access or are waiting on arrival you can clean them. Manually remove the debris on the filter into the garbage to the best of your ability, or with a vacuum cleaner. You may choose to use a handheld vacuum to assist you.

Once you remove a majority of the debris, clean the filter with a faucet sprayerhead if you use a permanent solution.

Allow the filter to dry completely (you don’t want to encourage mold development in your AC unit with excess moisture).

Step Four: Restore Air Filter and Power to Unit

Once dry, place teh filter back into place and restore power to the unit.

You’re done!


A dirty air filter may cause your AC not to perform as expected, leaving you without the cold air you expect from your air conditioning system. While not the only cause, cleaning your air filter should be your first action to resolve the issue. If the problem still exists, talk to a professional HVAC tech for air conditioning repair or new air conditioner installation before summer weather hits.

Aiden Anderson

Aiden Anderson earned his Master’s in Environmental Engineering from the University of California, Davis, focusing his 20-year career on HVAC innovation and indoor air quality. Since joining our platform as a freelancer in 2020, Aiden provides insights into climate control solutions, eco-friendly technologies, and system optimization. His background includes roles in environmental impact assessment and HVAC system design. His prior roles include engineering positions inmanufacturing and energy consulting. In his leisure time, Aiden enjoys woodworking and volunteering in community energy awareness programs.

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