Project Guide

How to Change a Home Air Filter

Difficulty: BeginnerTime: Under 2 Hours Print

When you can replace air filters in your home, you’ll be making strides toward cleaner air in every room. Central forced air heating and cooling systems rely on filter maintenance to help them run optimally over the long term. Read this guide to learn how to change an air filter.

1. Air Filter Maintenance Tips

  • Find your air filter location. You may have more than one air filter in the home to service. The return air register, the air handler cabinet and even a window air conditioner unit will all have an air filter that requires replacement or cleaning.
  • Before changing the air filter, get the correct size. Disposable air filters usually come surrounded by a cardboard frame, while reusable washable air filters have a plastic frame; either will indicate the specific size of the filter. When you search for a home air filter replacement, choose the same size. For filters that don’t indicate size, use a measuring tape to measure the length, width and thickness of the filter. Use these numbers to select a new filter.
  • Place the filter correctly. Most filters are printed with an arrow that indicates furnace filter airflow. Place the filter with an arrow pointing toward the furnace, in the direction of airflow. Correct placement is important. The unit will use more energy if the filter is not properly installed; it has to work harder to pull air through the opposing side.

Air filter replacement is important because it can extend furnace life, reduce energy bills and improve indoor air quality. Changing the air filter on a regular basis can improve your indoor air quality and help your HVAC system run more efficiently.

Tip: If you’re looking to replace your outside AC unit filter, the filter location varies depending on the unit. However, it can usually be found along the air conditioner return duct.

2. Replace Air Filter in Return Air Duct

  • Follow these easy steps on how to change a central air conditioner filter. First, unhook the latch on the cover grille.
  • Wipe the grille clean with a microfiber cloth. If dust has built up between the slats, wrap the tip of a flat screwdriver with a microfiber cloth and use it to gently clean in between the slats or vacuum the cover with a brush attachment.
  • Insert a new filter, ensuring the correct furnace filter direction.
  • Close the cover grille and secure the latch.
  • Remember to replace the air filter in your return air duct, air handler cabinet, window AC unit and furnace, if applicable.

3. Replace Air Filter in Air Handler Cabinet

  • Turn off the power to the HVAC unit. If you are unsure how to turn off the furnace, consult your unit’s manual. Do not run furnace without a filter in place.
  • Remove or unlatch the door and clean as indicated above.
  • Check the filter type. If it is disposable, replace with a new filter in the correct size.
  • If the filter is reusable, first brush it to remove surface dirt, then run a vacuum with a soft brush attachment over the face to pull out more embedded dust and dirt.
  • Run water through the filter in the opposite direction of airflow; you can use a low-pressure spray to assist in the cleaning.
  • Allow the reusable filter to thoroughly air dry before you replace it.
  • Do not resume power to the HVAC unit until the clean, dry filter is in place.

4. Replace Air Filter in Window AC Unit

  • The first step on how to change an AC filter is by turning off the AC and unplugging the unit.
  • Remove the front cover; if needed, clean as indicated above.
  • Remove the filter and shake vigorously outside to dislodge as much dust and dirt as possible.
  • Rinse the filter lightly with soapy water, then rinse with clear water until clean.
  • Scrub the cover in the soapy water, then rinse and dry with a microfiber cloth.
  • Air-dry the filter thoroughly before replacing it in the unit.
  • Replace the filter, lining up the notches on the filter frame with the spaces inside the filter compartment.
  • Replace the cover and restore power to the unit.

While knowing how to change an air filter is necessary, regular professional HVAC maintenance is a good idea, even when you are keeping up with replacing air filters regularly. Schedule inspections at least twice a year to keep ahead of any seasonal issues. Look into our subscription services to get select items, such as subscription eligible air filters, conveniently delivered straight to your home.