Can a Dirty Air Filter Cause Your AC Not To Cool?



In case you find your AC struggling to cool the room adequately, it could possibly be because the air filters are too dirty. Dirty air filters are actually one of the most common reasons behind poor AC performance. Air conditioners require regular maintenance to keep delivering optimal performance.

While you should get your AC routinely serviced by a professional at least once or twice a year, you need to clean or replace dirty air filters more often. Thankfully, you don’t always need to hire a professional to deal with dirty air filters – you can clean or replace them yourself.

Check out this article to learn how to change dirty air filters in an AC. Of course, if you find the process too complicated or feel unsure about being able to do it, you can always opt for professional assistance. A reputed AC repair and maintenance company like Hurliman should be able to help you out with it.

How does an air filter get clogged?

Air conditioners have air filters installed over the inlet to block debris, dust, pollen, and other particles. By filtering the air, these filters prevent contaminants from accumulating inside the AC. This helps protect the internal components from such debris. Moreover, cleaning or replacing the air filters is far easier than cleaning the interiors of an AC.

However, as the air filters continue to filter particles from the air while the AC is running, the particles keep accumulating on them. This gradually starts to close up the pores, and at some point, the air filters will become clogged with dirt. Unless you clean or replace them, the clogged air filters will significantly hamper your AC’s performance.

Why does a dirty air filter affect cooling?

You might wonder how the cooling performance of your AC unit is related to the condition of the air filters in any way. Well, to get a better understanding of it, let’s first visualize the working principle of an AC.

An air conditioner works by passing air against the cooling coil. The air inlet constantly sucks in warm air from the room and supplies it to the system. The warm air flows against the cooling coils, with refrigerant flowing inside them. The resulting transfer of heat causes the air to cool down, after which the AC expels it into the room.

When dirt clogs up an air filter, it significantly restricts air inflow. Now the air can only pass through the pores that are still open. Unless the AC receives a steady supply of air in the first place, what is it going to cool? As the air filters get dirtier, they might clog up entirely and prevent the AC from cooling at all.

Other problems caused by dirty air filters

Besides preventing your AC from cooling the room properly, dirty air filters can cause several other issues. These include:

1. Poor energy efficiency

Poor performance automatically results in poor efficiency. When your AC is no longer cooling the room the way it’s supposed to, it strains to bring down the room temperature to the desired level. This means the cooling function has to run longer before the desired temperature is achieved, consuming more power.

2. Overheating

A heavily clogged air filter can also cause your AC to overheat. When your AC struggles to cool the room and maintain the desired temperature level, it has to work much harder than usual. This can cause the unit to overheat, resulting in a chain reaction of other issues. An overheating AC would go faulty often and require frequent repairs.

3. Frozen evaporator coils

Air filters with extreme clogs can cause the evaporator coil (cooling coil) to freeze. The cold temperature of the evaporator coil causes condensation around it. When an AC functions normally, the airflow is enough to dissipate the condensation. However, poor airflow due to a clogged air filter will cause the condensation to remain on the coil.

Eventually, the condensation will build up and the cold temperatures will cause it to freeze into ice. Cold air building up inside the AC due to poor airflow also plays a role in freezing the evaporator coil by forcing the internal temperature to drop. A frozen evaporator coil can render your AC completely inoperable.

Signs that your AC has dirty filters

Thankfully, you don’t have to wait for major issues to crop up to show that your air filters need cleaning. There are several signs that you may look out for:

1. It takes longer to cool the room

As mentioned earlier, one of the first effects of a dirty air filter is a decrease in the AC’s cooling performance. If the air conditioner is taking longer than usual to cool the room, it’s possibly because the air filters have become too dirty.

2. Poor air quality

Your AC helps keep the air in the room clean and fresh by filtering contaminants. However, when the air filters clog up with dirt, they can no longer clean the air efficiently. This can make breathing a little uncomfortable and potentially trigger allergic symptoms. If you notice such issues, the chances are high that your AC has dirty filters.

3. Increased energy usage

An unusual increase in your energy bills is a sign that your air conditioner might have clogged air filters too. If you can’t figure out why you are getting higher energy bills, you should definitely check the filters.


If your AC is underperforming or showing signs of trouble, all you have to do is open it up and check the condition of the air filters. It will only take a few minutes and will help extend the lifespan of your air conditioner while fixing its performance issues. You can either clean/replace the filters yourself or rope in a reputed company like Hurliman to handle the job.