How to Select and Replace an AC Air Filter

Your home air conditioner’s air filter is a critical component to a properly-working system and to helping you avoid costly Phoenix air conditioning repairs. When purchasing your monthly replacement filter, you want to make sure you’re buying the right one for your system and your family’s needs.

A filter’s efficiency is measured in MERV (Minimum Efficiency Reporting Value) ratings. This rating tells you the ability of an air conditioning filter to remove dust from the air as it passes through the filter. A higher MERV rating means fewer dust particles and other airborne contaminants pass through the filter. Most residential air filters have a MERV rating of one to four, while commercial cooling system filters have a five or more MERV rating.

Types of Filters

Here is a brief rundown on the different types of filters available:

  • Disposable fiberglass filters: These are the least expensive type of disposable filter and are good at capturing large particles like lint and dust. They protect your HVAC unit but don’t do much to improve indoor air quality.
  • Washable air filters: While they don’t require replacement as often, these filters usually have a very low MERV rating and are not as proficient at removing smaller particles like pet dander, cigar smoke or hair spray, as a disposable filter.
  • High-efficiency air filters: These filters have the highest MERV ratings. High-efficiency particulate absorption or HEPA filters must satisfy certain standards of efficiency set by the U.S. Department of Energy. To qualify as HEPA, an air filter must remove 99.97 percent of particles that have a size of 0.3 µm or larger. They are most often used in hospitals, commercial buildings or industrial settings.

Changing the Filter

Changing a filter is easy to do and is an important step in prolonging the life of the unit and staving off Phoenix air conditioning repairs. First, consider the level of efficiency you will need. If you or members of your family are prone to allergies or asthma, consider purchasing a filter that ranks higher on the MERV scale. The higher the rating, the more efficient and effective the filter is at collecting debris in the air.

Next, you want to determine what size filter you will need. Take a look at your AC unit’s existing filter or bring it with you to the store for guidance. Purchasing the correct size filter is important in ensuring your home’s air quality is not compromised.

Finally, once at home, you’ll want to locate the AC register, which is usually close to the thermostat. Open the front grille and you’ll be able to then easily pull the old filter out. When putting the new filter in, look at the side of the filter. There should be an arrow or directions showing you which direction to put the new filter in.

The Phoenix air conditioning contractors at Chas Roberts are your filter experts! To schedule an appointment with an experienced Chas Roberts technician, visit or call (602) 943-3426 in Phoenix, (520) 618-1884 in Tucson or (505) 264-7257 in New Mexico.