Key Takeaways
- Uncomfortable temperatures and system breakdowns can indicate a clogged air filter.
- New filters cost between $2.50 and $50, depending on the type and lifespan.
- HVAC maintenance plans include air filter replacement and offer excellent value.
Unusually high energy bills, poor airflow from your HVAC vents, dust or musty odors in your living space, and worsening allergy symptoms or allergic reactions can all point to a clogged air filter in your HVAC system.
Once you’ve inspected and confirmed that your filter is clogged, you’ll want to clean it or replace it, depending on the type. For example, disposable fiberglass filters need to be changed every month, while electrostatic filters only need to be cleaned every month — and replaced about every five years.
“A dirty air filter does more damage than people realize,” said Randal Fuller, owner of Fuller Services, a full-service HVAC company in Northern Alabama. “When airflow is blocked, your HVAC system has to work much harder than it’s supposed to. That leads to higher energy bills, more wear and tear on the equipment, and even a shortened system lifespan.”
We’ll cover how to check if your filter is clogged, how often you should change it, and how to choose the right replacement filter to help you stay on top of one of the most important aspects of your preventative HVAC maintenance.
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Symptoms of a Clogged Air Filter
Clogged air filters restrict airflow in your HVAC system, which means your system works harder to provide heating and cooling. Keep an eye out for these key symptoms.
Weak Airflow From Vents
Airflow restrictions due to clogged air filters mean poor circulation and less effective heating and cooling, even among the best AC brands.
“One of the first things we usually hear from homeowners is that certain rooms just don’t feel as comfortable as they should,” Fuller said. “Maybe the air feels weak coming through the vents, or the temperature never quite reaches what the thermostat says. That’s often a clear sign of a clogged HVAC air filter.”
Higher Energy Bills
When your air filters are clogged, it will be harder for air to pass through them, which means your air handler will work overtime to maintain good airflow. Unfortunately, this means your blower motor will consume more energy to keep up with demand, and you’ll see that reflected on your heating and cooling bills.
HVAC System Overheating or Shutting Down
If your system shuts down unexpectedly or cycles on and off from overheating, a clogged air filter could be the culprit.
“A clogged filter reduces airflow, and when airflow drops, the evaporator coil in your AC can get too cold and freeze, turning a $10 filter problem into a system shutdown,” said Jimmy Hiller, president of Happy Hiller, a plumbing, HVAC, and electrical contractor based in Tennessee. Compared to the cost of replacing an AC system, swapping out filters is a small price to pay.
Excess Dust in the Home
HVAC air filters scrub dust, pollen, and other debris out of your indoor air. When they get clogged, pressure builds up behind the air filters and can force air and contaminants through gaps around the filter instead of through the filtering membrane. If you find yourself dusting and vacuuming more often, it could be a sign of a clogged air filter.
Musty Smells and Poor Indoor Air Quality
As more dust accumulates in your HVAC vents and isn’t scrubbed out by a clean filter, it can clog your condensate drain and cause leaks. Water accumulation will eventually lead to mold growth, which can create musty odors as mold spores leak through into your living area.
Increased Allergy or Respiratory Issues
Finally, allergy symptoms can indicate a clogged HVAC air filter. Dust, pollen, pet dander, and mold spores that would normally get trapped in your filter can leak out from your vents into your living area. You may notice itchy eyes, a runny nose, or worsening respiratory problems, like asthma.
It can be easy to forget to keep up with HVAC maintenance. Set reminders on your phone to check filters monthly and swap them out if they appear dirty.
How To Check If Your Air Filter Is Clogged
Suspect your HVAC filter might be clogged? You can follow these simple DIY steps to check yourself:
- Turn off your HVAC system.
- Open the HVAC return, which is a large air intake vent, usually in your main living area, located on or near the ceiling.
- Carefully unclip the filter and remove it.
- Check the filter for tears, kinks, and other physical damage. If the filter is damaged, replace it.
- Hold the filter up to the light. “If little or no light passes through it, replace or wash it,” Hiller said.
Why a Clogged Air Filter Is a Big Problem
Maintaining clean air filters may not seem like a big deal, but clogged filters can spell big trouble for you and your home.
First off, it will cost you money. Restricted airflow means that your air handler will work harder to distribute conditioned air to your living space. This means higher utility bills, which can add up over time.
More importantly, that added strain placed on your air handler will mean more frequent breakdowns and a shortened system lifespan. Repair and replacement costs will also be higher in the long run if you continue to run your system with clogged air filters.
Finally, poor air circulation caused by clogged air filters will make your home less comfortable. Not only can allergens become more prevalent in your living space, but your system will struggle to keep up with heating and cooling demand due to the restricted airflow, which means less comfortable temperatures.
To avoid these issues, follow your system manufacturer’s recommendations for filter replacement.
How Often Should You Replace Your HVAC Air Filter?
You should aim to replace your HVAC filter every one to three months, depending on a few factors.
Homeowners who live in extreme climates and rely on their systems for heating or cooling constantly should replace them more often. “In our Alabama climate, where systems run nearly year-round, we tell customers to check their filter monthly and replace it as needed,” Fuller said.
If someone in your home has severe allergies, you should also consider monthly replacement to maximize the volume of allergens your filters remove from the air.
Replacing filters every one to two months is also best if you have a high concentration of allergens, like multiple pets living in the home. “I always tell people if you’re even slightly in doubt, just swap out that $15 filter — it’s a small price to avoid hundreds of dollars in repairs later,” Hiller said.
Finally, the type of filter you have can determine how often you need a replacement.
- Disposable fiberglass filters: replace every 30 days
- Disposable pleated filters: replace every 60 to 90 days
- Washable electrostatic filters: clean every 30 days; replace every five years
- HEPA filters: replace every six to 12 months
You should change out high-efficiency filters for commercial systems every three to 12 months, in most cases, but follow the manufacturer’s recommendations for the best results.
Choosing the Right Replacement Filter
You’ll need to choose the right replacement filter for your system. Start by getting the right size. You can remove your existing filter to check the model number or take measurements. Depending on the type of HVAC system you have, this could be located in the air return or inside your air handler.
If you recently purchased your home, the prior owner or builder may have left extra filters in a utility room or storage closet. The boxes will have dimensions on them.
Consider the cost of the filter and the value you’ll get out of it. Fiberglass filters cost as little as $2.50, but they only last 30 days. Electrostatic filters can cost around $50, but they’re reusable and can last up to 10 years.
| Filter Type | Cost | Lifespan |
|---|---|---|
| Fiberglass (disposable) | As low as $2.50 | 30 days |
| Pleated (disposable) | As low as $6 | 60–90 days |
| Electrostatic (reusable) | ~$50 | 3–10 years |
| HEPA (disposable) | ~$30–$50 | 6–12 months |
You may also want to take into account your filter’s minimum efficiency reporting value (MERV) rating. Ratings range from 1 to 20; higher numbers scrub out more dust and other particles. Filters with higher MERV ratings will cost more, but they keep your indoor air clean and healthy.
Next Steps
Keeping up with air filter replacements on your HVAC system can help reduce strain on your system, limit how often you need maintenance and repairs, lower your energy bills, and help keep your family safe from indoor pollutants and allergens. If it’s been a while since you last replaced your HVAC filters, consider swapping them out now to avoid problems. Upgrade to a higher MERV rating or even a HEPA filter if you or your family members struggle with allergies or respiratory issues.
While you’re at it, pick up some extra filters to keep on hand, and set reminders for yourself to replace the filters again in one to three months, depending on the type of HVAC filter you install. Proactive HVAC maintenance can help extend your system’s life, make your home more comfortable, and avoid expensive breakdowns, too.
“Most HVAC companies cover air filter changes along with stuff like cleaning the coils, checking refrigerant, tightening electrical connections, clearing out the drain line, and just making sure everything’s running like it should before the season kicks in,” Hiller said. “Even though replacing filters is easy and every homeowner can handle it, not everyone gets around to it due to busy schedules or just forgetting, so having it built into a maintenance plan makes sure it actually gets done and prevents expensive repairs in the future.”
Contact an HVAC pro in your area to set up recurring maintenance to take the guesswork out of scheduling air filter replacement.
FAQs About Clogged Air Filters
How long can I go without changing my HVAC air filter?
The timeline depends on the type of filter. You can safely go up to three months without changing standard disposable pleated HVAC filters. Fiberglass filters that are used longer than 30 days can affect indoor air quality and place excess strain on your HVAC system.
Similarly, you should remove and clean reusable electrostatic filters once a month to avoid issues, and replace them every five years or if they sustain damage. HEPA filters can work properly for six to 12 months. These timeframes can decrease if your filters work overtime to remove debris, such as pet dander, excessive pollen, and dust.
Can a dirty air filter cause my AC not to work?
Yes, a dirty air filter will restrict airflow through your HVAC vents and put undue pressure on the air handler that moves air through your system. Over time, that added strain can cause breakdowns that leave you without heat or AC.
Even if the issue doesn’t get to that point, you’ll experience more allergens and pollutants in your indoor air if you don’t change your filter regularly — and you’ll experience less comfortable living temperatures.
Will changing my air filter reduce my energy bill?
Changing the air filters in your HVAC system can reduce your energy bills if your existing filters are clogged, causing your air handler to work harder to distribute conditioned air. Changing your air filters regularly and carrying out routine maintenance are good ways to reduce energy bills and prolong system life, according to the U.S. Department of Energy.
Are expensive air filters worth it?
Expensive air filters like HEPA filters and those with high MERV ratings usually provide less lifespan for the money, but they can still be worth the investment because they scrub out more pollutants from your indoor air.
High-efficiency filters remove more dust and can even pull out tiny particles, such as pollen and pet dander. If you or someone in your home has allergies or existing respiratory issues, these high-end filters will often provide greater comfort in your home, making them worth the money.
