Do you recall the last time you replaced your HVAC system’s air filter? If not, you aren’t alone. People often forget this important task unless there’s a sign that a heater’s or air conditioner’s clogged filter is causing problems.
A dirty home air filter can prevent your furnace or AC unit from working properly. If the filter media is completely clogged, the system can shut down; overheating and excess strain may even cause the compressor to fail. Therefore, a costly equipment repair and replacement might be required, but you can avoid high expenses by replacing the AC or furnace air filter. It’s one of the most affordable and easiest to install parts of your heating and cooling system.
Are you noticing dusty vents, weak airflow, or inconsistent temperatures at home? These are signs of a clogged or dirty filter. Even a higher-than-normal energy bill can mean it’s time to change it.
We’ll look at common signs of a clogged furnace or AC filter, so you can know when to replace it to avoid more serious problems.
Signs of a Clogged or Dirty Air Filter
Here are seven of the most common symptoms that a filter has become so clogged with dirt, dust, and debris that your HVAC system can’t function properly:
1. Dust Around Vents
An air filter traps dust and particulates. If it’s clogged, it can no longer capture dirt effectively, so debris can get into the system and circulate. It can pass into the ductwork and eventually settle on vent registers and grilles. In the process, dust can settle inside air ducts, which also reduces HVAC performance and efficiency.
If you see dust covering air vents, chances are the filter is dirty and needs to be replaced. You may also find that surfaces throughout your home, including tables, countertops, and furniture, are dustier than usual.
However, if you’ve recently changed your air conditioner’s clogged filter, persistent dust can be caused by a different issue, such as:
- Leaky Ductwork: Gaps, holes, and tears in air ducts can allow dust from outside or unconditioned parts of your home to enter the system.
- Gaps Around Windows and Doors: Spaces around window and door frames can let in dust, depending on the direction and strength of the wind.
2. Reduced Airflow from Registers
Occasionally, you should check the strength of the airflow from vents. Any noticeable changes can mean a problem is brewing in your HVAC system. Reduced airflow is also a common sign of a clogged filter, as air may be struggling to pass through the dirt that’s coating it.
Weak airflow makes it harder for your HVAC system to heat or cool your home. It may then run longer or at a higher setting to compensate, which can increase energy usage and strain components. Replacing your dirty home air filter with a new one restores the normal airflow into the system and from vents (and keeps everything running smoothly).
3. Spike in Energy Bills
Have you noticed an increase in your monthly electric bill? Unless your local utility company has sent you a notice that its rates have increased (utilities typically don’t raise rates so dramatically), there could be an issue with your HVAC system. The problem is often as simple as a clogged filter, which causes your AC or furnace to work harder and inefficiently.
A clogged filter won’t stop your air conditioner or heater from trying to maintain a comfortable temperature. But compensating for the lack of airflow increases energy consumption, and you pay for all that wasted energy. Replacing the filter is a minor expense compared to how much you may otherwise pay for energy over time.
4. More Frequent Allergy Symptoms
Air filters can trap dust mites, pollen, pet dander, and other allergens aside from dust. These become trapped when a filter is dirty and can recirculate in your home. A clogged filter is a likely culprit if you or members of your household have frequent or worsening allergy symptoms like the following:
- Sneezing
- Runny nose
- Sinus congestion
- Itchy eyes
- Coughing
- Wheezing
- Shortness of breath
The particulates in a dirty filter can also trigger more frequent and more severe asthma attacks in sensitive individuals. Therefore, replacing it can help improve your health and well-being.
5. HVAC System Is Running Constantly
Your heating and cooling system is designed to match the desired temperature that you set on the thermostat. This is harder to achieve if not enough air can pass through the filter. When your home isn’t warm or cool enough, the system will run continuously as it struggles to maintain a comfortable temperature.
Normally, an HVAC system cycles on and off a few times per hour. If it doesn’t, serious damage can occur. Aside from increased energy consumption, this can potentially cause the system to overheat. Don’t ignore it when your AC or furnace never shuts off. Replacing the filter or calling a professional can save you from costly repairs.
6. Strange Odors From Vents
An old, dirty filter can trap more than dust and dirt. It can also harbor mold and bacteria, which can cause a foul and persistent smell. Some liken this odor to that of dirty socks (which can also mean there’s biological buildup on the evaporator coil).
Lingering odors can be addressed by replacing the filter. If something still doesn’t smell right, check the drain pan and clean it if necessary, or have a professional inspect your ductwork and determine if duct cleaning, sealing, or repair is required.
7. Uneven Room Temperatures
While your HVAC system may take longer to heat or cool your home, a clogged filter can also affect temperature distribution. Less conditioned air is available to reach rooms, especially those located farther from the AC or furnace. As a result, some areas will be much warmer or cooler than others.
Check the air filter when there are noticeable temperature differences from room to room. Replacing it may be all you need to do to restore optimal comfort.
Frequently Asked Questions
What Happens If You Don’t Replace a Dirty Filter?
If a dirty home air filter isn’t replaced, the materials it’s designed to trap create a thick barrier that blocks airflow. This can decrease energy efficiency, increase wear and tear, and shorten a heating or cooling system’s lifespan.
How Often Should You Replace Your HVAC Filter?
An AC/furnace filter should be replaced every 1 to 3 months. Thinner, less efficient filters should be replaced more frequently than higher quality ones (such as HEPA filters). Replace the air filter if you use your HVAC system more frequently, the environment is more contaminated, or you have pets.
How Do I Check If My Air Filter Is Dirty?
To see if your air conditioner or furnace has a clogged filter, check it directly (the filter is usually near the air handler, but may be behind a cabinet panel or a return air grille). A dirty one will look coated in dust and dirt. Torn or damaged filters should also be replaced.
Can My AC Work without a Filter for a Short Time?
Your air conditioner will operate with no filter. However, letting it run for just a few short hours can be harmful. Once particles go past the blower, they can coat the evaporator coil and damage the compressor.
Changed the Air Filter and Your HVAC System Is Still Not Working Properly? Call Calvey Heating & Air
Timely filter replacement and HVAC maintenance can prevent damage and costly repairs. Therefore, always check the air filter if any of the issues we’ve mentioned occur. We’re also here if you have any questions. A family-owned and operated business, Calvey Heating & Air delivers high-quality, honest, and affordable heating and cooling solutions. Homeowners in San Jose, Mountain View, Los Altos, Pleasanton, Cupertino, and surrounding areas benefit from our transparency and premium service.
Whether your heater’s or air conditioner’s clogged filter must be replaced or you suspect a different issue, contact us today.