4 signs it's time to replace your air filter

Let’s face it. Your air conditioner filter is probably the least sexy thing in your home—it’s a cardboard frame with some fibers in the middle. Don’t let its humble appearance fool you; your air filter plays a huge role in keeping your home cool and keeping your electricity bills down. Changing out your air filter is a critical part of AC maintenance.


What Air Filters Do

Air filters, typically constructed of spun fiberglass, clean the air that circulates through your heating and cooling system by trapping and containing contaminants such as pollen, mold spores, pet hair, microorganisms, dust, and more. Over time, the filter will capture so many contaminants that it becomes clogged. When this happens, air flow is restricted, reducing the efficiency of your system, and the filter may also begin releasing contaminants into the system.

When air filters become dirty and clogged, it can greatly reduce the efficiency of your air conditioning unit. According to the Department of Energy, running your heating and cooling system with a clogged air filter can cause you to use 5 to 15 percent more energy than you’d consume if your filter were clean. Considering the fact that up to half your monthly power bill derives from heating and cooling energy use, maintaining optimum efficiency in your heating and cooling system is a smart and easy way to keep your power bills down.

Over time, a clogged filter can contribute to greater wear and tear on your unit, resulting in increased maintenance and repair needs. When air flow is restricted by a clogged filter, your unit must work harder to produce the desired temperature in your home. By keeping clean filters, you can reduce your unit’s workload, extending its useful life.

Regularly maintaining your heating and air system’s air filters can also help prevent your home from having indoor air quality issues. Recent studies have identified indoor air quality as a huge public health concern. Poor indoor air quality has been linked to short-term problems such as eye irritation, headaches, and exacerbation of allergies and asthma.

Increasing evidence is also pointing to a link between poor indoor air quality and cancer. Keeping contaminants from circulating and recirculating throughout your home can greatly improve its air quality.


When It’s Time to Change Your Filter

It’s easy to forget about your air conditioner’s filter. It’s typically tucked away in an access closet in an out-of-the-way corner of your house. However, as demonstrated above, it’s well worth your while to inspect and change your air filter as needed.

In general, you should replace your air filters every two months to ensure that they operate at optimum efficiency. If calendars and maintenance schedules aren’t quite your thing, knowing a few of the warning signs that your air filter is in need of changing can help you improve your air filter’s efficiency and longevity.

  • You notice that dirt and dust are accumulating around your air vents – When air filters get clogged, they often begin releasing dirt and contaminants into the system, which can wind up getting expelled through the vents. Dirt and dust around the vents don’t always mean your filters need changing—it can also indicate clogged ducts—but if you’re noticing this problem, checking your filters is a worthwhile first step.
  • Your electricity bill spikes for no apparent reason – Remember, a big chunk of your monthly power bill is derived from the energy your home uses for heating and cooling. A clogged air filter will make your unit work harder to control the temperature in your home, consuming more energy. If your bill increases, and you don’t have another explanation, checking your filter may be a good idea.
  • Your filter looks dirty or damaged – A visual inspection can usually reveal whether your filter needs changing. Dirty, clogged, or otherwise compromised air filters will often be covered in dust and debris and may also have holes or signs of wear. If your filter is dirty or damaged, toss it out and replace it ASAP.
  • Your allergies get worse – If you notice that you or your kids are suffering worse allergy problems than usual, a dirty air filter may be the culprit. Changing the filter is a good first step to diagnosing the problem.

While a clogged air filter won’t be the only culprit in some of these scenarios, it is a likely candidate for many. Replacing your air filter on a regular basis can help you head off a lot of problems down the road.


Other Money-Saving Air Conditioner Maintenance Tips

Changing your air filter on a regular basis is one of the easiest and most effective ways to improve the efficiency of your home heating and cooling system, but there are several other ways you can optimize your unit’s performance and longevity.

  • Make sure your thermostat is on the right wall. The area around a window will typically be the hottest or coldest area in your home. If your thermostat is placed next to a window, this can skew the device’s determination of how hot or cold it is in the house, causing it to run more than needed.
  • Have your air ducts cleaned and EnergyStar estimates that about 20 to 30 percent of the air that moves through your HVAC system’s ducts is lost because of leaks and holes. Obstructed and dirty ducts can also reduce your HVAC system’s efficiency.


Having an AC maintenance contractor inspect and clean your ducts can help improve both efficiency and air quality. When air ducts accumulate dirt and debris, these contaminants are circulated throughout the home, negatively impacting the air quality. Having your ducts sealed will also help improve efficiency, as it will let less air escape.

When your system’s ducts are at peak efficiency, it reduces your unit’s workload, causing it to use less energy and also reducing the likelihood the unit will break down from overwork.

  • Check your windows. Windows are where a lot of the heat transfer between your home and the outdoors occurs. You can reduce heat transfer by installing modern windows if your windows are outdated. New modern designs reduce heat transfer. Properly sealing the area around the windows can also help with drafts.
  • Install a programmable thermostat. New thermostats allow you to program the devices to come on or off at certain times of the day. This can help you avoid running your heat or AC when no one is around to need it. Also, some new thermostats can be controlled by your smartphone, meaning that if you forgot to dial down the AC before you left, you can do it from the office.
  • Upgrade to a new unit. The useful life of an air conditioning unit is typically 10 to 20 years. Toward the end of their lives, units will often perform significantly less efficiently than they once did. New technology developed since you purchased your old unit and now will also likely offer a big efficiency advantage for a new unit.

When you need air conditioner maintenance service, don’t try to puzzle through it alone using YouTube videos. Get in contact with HVAC professionals who can ensure the job is done correctly. Talk to your friends about the company you should hire and, also, employ Google to read reviews of the various air conditioning maintenance and repair companies available.

Kaiser Air Conditioning, a family-owned air conditioning service, provides heating and cooling system repair, installation and maintenance to homes and businesses in the Oxnard, California area. Kaiser was established in 1981 and has grown from having just a single truck and a small facility to having 12 trucks, 20 employees, and a 5,000-sq.ft. sheet metal fabrication facility.



  1. https://www.energy.gov/energysaver/maintaining-your-air-conditioner
  2. https://www.energystar.gov/index.cfm?c=home_improvement.hm_improvement_ducts