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How Dirty Filters Affect Air Conditioners

The air filter is a lifesaver for your air conditioner, but it’s also one of the biggest

For your AC, it’s essential to keeping dust and dirt out of the sensitive components. For you, it’s another thing to add to your list of reminders. That’s because the air filter will get clogged with dirt, and if you don’t remember to change it regularly, it can cause a whole range of problems that appear more drastic than they really are.

When your air filter is clogged, it prevents new air from entering your system. This forces your AC to work harder to pull in clean air. It turns out that blocking the airflow in your AC will bring a slew of problems, such as:

Low Airflow

After that explanation of air filters, low airflow is the least surprising item on this list. In particular, this problem is complicated by your air conditioner’s ducts. Your AC depends on strong airflow and a fan to blow the newly created cold air through the ducts and into the rooms of your home. If this airflow is compromised by a clogged filter, you can expect to feel a lower flow of air coming from your vents. Your AC won’t work just harder but also longer to keep up with the demands of the thermostat.


When it comes to short-cycling, the process of your air conditioner turning on and off too rapidly, a dirty air filter would actually be the most desirable case. Causes of short-cycling are often due to more substantial problems like an over-sized AC unit or a refrigerant leak. If replacing the air filter doesn’t stop your short-cycling problems, then you should immediately call for air conditioning repair in Woburn, MA since it means that you most likely have a serious AC problem. If not resolved soon, it could result in AC failure at worst or spiked energy bills at best.

Frozen Evaporator Coils

You wouldn’t expect a dirty air filter is capable of this problem, especially if you’ve never heard of it before.

In both the outdoor and indoor units of your air conditioning system, there are metal boxes full of copper tubes called coils. The indoor coil, the evaporator coil, absorbs the warm air from inside your home to send it outdoors. If the evaporator coil is unable to absorb heat, however, it can cause things to get real cold real fast.

In the case of the dirty air filter, excess dirt and dust will cover the evaporator coil and create an insulator. Before long, the coil will get so cold that it becomes a big block of frost and ice. If this happens, turn off the air conditioner to let the ice thaw, and call in a repairman. Similar to short-cycling, a frozen coil can be caused by much bigger problems that you’ll want to have checked on sooner rather than later.

Got a bigger problem than a dirty air filter? We can help! Contact Cooling Unlimited, Inc. to find out how we can meet your unique heating and cooling needs.

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