Can a Dirty Air Filter Cause Overheating? A Tampa AC Tech Answers

October 23, 2018

Yes, a dirty air filter can cause certain components in your system to overheat—which will eventually force the entire HVAC system to shut down.

You see, your HVAC system needs to “breathe” air in and out in order to cool/heat your home. But a clogged filter restricts the amount of air that your system can breathe in. This lack of airflow can cause various AC and furnace problems—all of which lead to overheating and system shutdown.

This can lead to costly AC repairs over time as your HVAC system becomes overworked. Let’s take a closer look at exactly how a dirty filter affects your air conditioner/furnace.


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How a clogged filter affects your HVAC system

We already know that a dirty filter essentially suffocates your HVAC system. But how does a clogged filter affect your air conditioner versus your furnace?

We’ll show you…

AC problems caused by a clogged filter

  • Overworked blower motor. Your air conditioner and furnace both share a crucial component called the “blower motor.” The blower motor is responsible for pulling air into the HVAC system. Which means, if something prevents air from entering the system (i.e. a clogged filter), the blower motor now needs to work harder to pull in enough air. And eventually, a blower motor that’s overworked will overheat and shut down.
  • Frozen evaporator coils. Your AC evaporator coils absorb heat and moisture from your home’s air. These coils are filled with cold refrigerant. But if there’s not enough warm air passing over the coils (due to a clogged filter), the refrigerant continues to drop in temperature. And, eventually, those coils freeze over. And when the coils are frozen, your AC will run continuously and still not cool your home down. Eventually, the components in your AC will overheat and the system shuts down.

Related reading: What to Do If You Have Frozen Evaporator Coils

Blower Motor Evap Coil

Furnace problems caused by a clogged filter

  • Overheating heat exchanger. The heat exchanger is the part in the furnace that actually heats the air. Air is pulled into the furnace, heated as it passes over the heat exchanger, then pushed back into your home. If a dirty air filter is blocking cool air from entering the furnace, the heat exchanger builds heat over time and eventually shuts the system down as a safety precaution.
  • Overworked blower motor. Your furnace shares a blower motor with your air conditioner. So regardless of whether you’re running the AC or heat, a dirty filter puts extra strain on the blower motor. Eventually, the blower motor can overheat and shut the system down.

“How often should I replace my filter to prevent all of this?”

Well, it depends on a number of factors (including where you live, how often you run the system, etc.).

But a general guideline is to check your filter every 1 to 3 months and change it even if you see a very thin layer of dirt on the surface of the filter.

Replacing your filter before it gets substantially clogged will help prevent expensive repairs (like a burnt out blower motor).

Need help from a Tampa HVAC tech? Just ask us

If you’re dealing with the repercussions of a clogged filter, contact us. We’ll send out a tech to inspect, diagnose and repair your system.

Have other HVAC questions? We can help with those too.

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