The Problem with Clogged Air Filters

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Updated 7/11/2024

Air filters play a crucial role in maintaining the efficiency of your heating, ventilation, and air conditioning (HVAC) system while ensuring clean, healthy indoor air. This guide will explore the importance of clean air filters, the consequences of neglecting them, and provide practical advice for homeowners to maintain optimal air quality and HVAC performance.

The air filter in your heating, ventilation, and air condition (HVAC) system cleans your indoor air as it circulates your home by removing dust, dirt, pet dander, and other allergens.

Keeping your A/C’s air filter clean is essential for you and your family’s health, comfort, and well-being.  However, work, family life, and other responsibilities keep us preoccupied, making cleaning the A/C air filter the least of our priorities.

What Happens When Your HVAC Air Filters are Dirty?

Clogged air filters are the primary cause of air conditioning problems, yet the air filter is usually the most ignored part of the air conditioner.

When air filters are dirty, indoor air quality suffers, energy bills increase, and the A/C will fail eventually.

Since we are inside our homes most of the time, poor indoor air quality can lead to health problems in the long run, such as allergies, asthma, and other respiratory conditions.  

An air conditioning filter

Understanding Air Filters and Their Function

Air filters are essential components of your HVAC system, designed to:

  • Remove dust, dirt, pet dander, and other allergens from indoor air
  • Improve overall air quality in your home
  • Protect HVAC components from debris accumulation

Types of Air Filters

There are several types of air filters available, each with its own advantages:

  1. Fiberglass Filters
    • Inexpensive and disposable
    • Basic filtration for larger particles
    • Low MERV rating (1-4)
  2. Pleated Filters
    • More effective than fiberglass filters
    • Capture smaller particles
    • Higher MERV rating (5-13)
  3. HEPA Filters
    • High-efficiency particulate air filters
    • Capture up to 99.97% of particles as small as 0.3 microns
    • Ideal for allergy and asthma sufferers
  4. Washable Filters
    • Reusable and eco-friendly
    • Require regular cleaning
    • May not be as effective as disposable filters

Understanding MERV Ratings

MERV (Minimum Efficiency Reporting Value) ratings indicate a filter’s ability to capture particles:

  • MERV 1-4: Basic filtration for larger particles
  • MERV 5-8: Medium filtration for dust, pollen, and mold spores
  • MERV 9-12: Superior filtration for fine particles
  • MERV 13-16: Hospital-grade filtration for bacteria and smoke

Your HVAC system also operates below average and does not cool your home as well as it should when your unit’s air filters are clogged. Your A/C must work harder and use more energy to compensate for the blocked airflow. Higher energy consumption means higher energy bills.

In addition to jacking up your utility bill, the reduced airflow can cause your heat exchanger to overheat, shut off quickly, and trip your system’s limit switch. If this happens, your HVAC system will stop working and need expensive repair.  

The simple task of cleaning and changing your air filter can reduce stress on your air conditioner, save you money on bills and repairs, make the temperature of your home comfortable, and improve your health.

Clogged Air Filter Problems

Most of us do not care about the A/C air filter until there is a problem. With air filters left unchecked, air conditioning problems can escalate and get worse in time. Dirty and clogged air filters result in these serious problems:

  1. Poor Indoor Air Quality
    • Increased allergens and pollutants in the air
    • Potential health issues for occupants
  2. Reduced HVAC Efficiency
    • Restricted airflow forces the system to work harder
    • Increased energy consumption and higher utility bills
  3. Uneven Heating and Cooling
    • Inadequate airflow leads to temperature inconsistencies throughout the home
  4. System Damage
    • Strain on HVAC components can lead to breakdowns
    • Potential for frozen evaporator coils
  5. Shortened HVAC Lifespan
    • Increased wear and tear on system components
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Unhealthy Indoor Air

Air filters catch dirt and debris and prevent them from circulating in the air so that you do not inhale them. Dust accumulates in the air filters. When air filters are dirty or clogged, indoor air quality suffers.  

If you smoke, keep chemicals, own pets, or have construction projects in your house, the indoor air quality will worsen with clogged filters.

Allergens, dust, mold spores, and other air contaminants that clogged air filters let circulate throughout the air can result in flu-like symptoms, trigger asthma attacks and other respiratory conditions, and cause chronic allergies.

If you already observe unwanted health effects in yourself or other family members, consult a doctor, change your air filters, and invest in high-efficiency particulate air (HEPA) filters that remove air particulates and contaminants.

High Energy Bills

Your HVAC system recirculates air continuously. If air cannot flow through your air filter, your A/C’s blower fan has to work harder to circulate air throughout your home, thus increasing your energy consumption.

According to the Department of Energy, clogged air filters use 15% more energy than clean ones. Using more electricity in heating or cooling your home means your energy bill will be higher than usual.  

Regularly changing your air filter makes sure that air circulates well so that your HVAC system does not use more energy than needed. Changing your air filters can reduce your energy use by 5 to 15 percent.

Lower energy consumption means more savings on your energy bill.

Poor Cooling and Heating

Clogged air filters can cause uneven hot and cold temperatures in your home. Even when the blower fan works double-time to circulate air, clogged filters block the passage of enough air from your air conditioning unit to your room.

With reduced airflow, you can expect some areas of your to be hotter than others. Aside from hot and cold spots, it will be difficult for your room to retain the indoor temperature you want.

Clogged air filters are the primary reason as to why your room is too cold, despite the furnace being on or too hot while the air A/C is set to the lowest temperature.

If your HVAC system is not cooling or heating to your desired temperature, check your air filters and have them cleaned or replaced immediately.

Frozen Evaporator Coils

If you notice ice forming in your evaporator coils, especially during the summer months, clogged air filters can be the culprit.

Water from condensation that should drip into the drain pan during the cooling process freezes instead. The cold air that cannot move well across the coil freezes the water from condensation.

Instead of removing heat from the air to cool your room, your HVAC system cannot perform its intended function due to frozen coils. Even worse, your A/C may breakdown and fail in the middle of sweltering summer heat because of frozen evaporator coils.

HVAC Shutdown

Clogged air filters can cause costly internal damage to your HVAC system when an overworked air blower overheats, breaks down, and causes the HVAC system to stop working.

Clogged air filters also wear out your A/C parts faster than usual, shorten your HVAC system’s life, and result in additional maintenance and repair costs.

How to Maintain Clean Air Filters

Cleaning Reusable Filters

Cleaning your air filter is a simple task that prevents HVAC system problems from happening. Just follow these simple steps:

  • Take the air filter out of your HVAC system. You can find it in the blower compartment.
  • Remove the dust and dirt from the air filter.
  • Run the air filter under warm water thoroughly.
  • Dry the air filter before reinstalling it.
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Replacing Disposable Filters

To replace disposable filters:

  1. Turn off the HVAC system
  2. Locate the filter compartment
  3. Remove the old filter
  4. Insert the new filter, ensuring correct airflow direction
  5. Close the compartment and turn the system back on

Recommended Replacement Schedule

The frequency of filter changes depends on various factors:

  • Standard 1-inch filters: Every 1-3 months
  • Thicker filters (4-5 inches): Every 6-12 months
  • Homes with pets or allergies: More frequent changes may be necessary

If you still experience problems with your AC after cleaning or replacing your air filter, contact a qualified HVAC professional immediately.


Choosing the Right Replacement Filter

Consider these factors when selecting a new filter:

  1. Size: Measure the existing filter or consult your HVAC manual
  2. MERV Rating: Balance filtration efficiency with system compatibility
  3. Thickness: Thicker filters generally last longer and provide better filtration
  4. Special Needs: Consider HEPA filters for severe allergies or respiratory issues

Beyond Air Filters: Improving Indoor Air Quality

While clean air filters are crucial, other steps can further enhance indoor air quality:

  1. Regular HVAC Maintenance
    • Schedule professional inspections annually
    • Keep vents and registers clean and unobstructed
  2. Duct Cleaning
    • Consider professional duct cleaning every 3-5 years
    • Address any visible mold or pest infestations promptly
  3. Use of Air Purifiers
    • Supplement HVAC filtration in high-traffic areas
    • Consider models with HEPA filters for maximum effectiveness
  4. Control Humidity Levels
    • Use dehumidifiers in damp areas to prevent mold growth
    • Maintain indoor humidity between 30-50%
  5. Minimize Pollutant Sources
    • Use low-VOC products
    • Avoid smoking indoors
    • Keep pets groomed to reduce dander
  6. Regular Cleaning
    • Vacuum carpets and upholstery frequently
    • Dust surfaces with a damp cloth to capture particles
  7. Ventilation
    • Open windows when weather permits to introduce fresh air
    • Use exhaust fans in kitchens and bathrooms
  8. Monitor Air Quality
    • Consider using air quality monitors to track pollutant levels
    • Address any consistent air quality issues

Seasonal Considerations

Different seasons bring unique challenges for indoor air quality:

Spring and Summer

  • Pollen levels increase, requiring more frequent filter changes
  • Higher humidity can promote mold growth


  • Falling leaves and plant matter can introduce new allergens
  • Prepare HVAC system for the upcoming heating season


  • Closed windows can lead to stagnant indoor air
  • Dry air may require the use of humidifiers

The Role of Professional HVAC Services

While regular filter maintenance can be a DIY task, professional HVAC services offer several benefits:

  • Comprehensive system inspections
  • Cleaning of components beyond the filter
  • Expert advice on improving system efficiency
  • Early detection of potential issues

Consider scheduling annual maintenance checks with a qualified HVAC technician to ensure your system operates at peak performance.

Contact Home Comfort USA for Air Filter Check and Air Conditioning Maintenance

To replace the air filters of your HVAC system, diagnose, and repair other problems brought by clogged air filters, schedule an air conditioning maintenance with an HVAC professional.

At Home Comfort USA, our HVAC experts will inspect your HVAC system to ensure that it is running efficiently. We will check, clean, change your air filters, and perform a 32-point check-up to give your unit utmost care and keep it running adequately.  

For fast and reliable HVAC system installation, repair, and maintenance services in Anaheim, Orange County, Los Angeles, Inland Empire, and other areas in Southern California, call Home Comfort USA at (888) 462-0089 or schedule an appointment today. 

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