How to Change Your AC Air Filter: A Simple Step-by-Step Guide 

Changing your air filter is one of the easiest ways to keep your HVAC system running efficiently. A clean filter improves airflow, helps keep your home cooler, lowers energy costs, and protects your air conditioning system from unnecessary wear and tear.

Whether you're a homeowner or a tenant, replacing your AC filter only takes a few minutes and can help prevent costly repairs.


Step 1: Locate Your Air Filter 


The first step is finding where your air filter is installed. Common locations include:

  • Behind the return air vent on a wall or ceiling
  • Inside the HVAC unit
  • In the air handler closet
  • Behind a return grille in a hallway


If you're unsure where your filter is located, refer to your HVAC owner's manual or ask your property manager.


Step 2: Purchase the Correct Filter Size 


Before buying a replacement, remove the existing filter and check the size printed on the frame.


Common filter sizes include:

  • 16 x 20 x 1
  • 20 x 20 x 1
  • 20 x 25 x 1
  • 16 x 25 x 1


Using the correct size is important because an improperly fitted filter allows dust and debris to bypass the filter and enter your HVAC system.


Step 3: Install the Filter in the Correct Direction 


Every air filter has an airflow arrow printed on its frame.

When installing the new filter, make sure the arrow points in the direction of the airflow—toward the HVAC unit or air handler, not toward the room.


Installing the filter backward can reduce system efficiency and limit airflow.


Step 4: Clean Around the Filter Area 


Before inserting the new filter, take a moment to clean around the filter opening.


Remove any dust, dirt, or debris that has collected around the return vent or filter compartment. Keeping this area clean helps prevent contaminants from entering your HVAC system.


Step 5: Write the Replacement Date on the Filter 


Once you've installed the new filter, use a permanent marker to write the installation date directly on the filter frame.


This simple reminder makes it easy to know when it's time for the next replacement and helps you stay on schedule.


How Often Should You Replace Your Filter? 


In Houston's hot climate, air conditioners often run for long periods, especially during the summer. Check your filter every month and replace it whenever it appears dirty or according to the manufacturer's recommendations.


Homes with pets, allergy sufferers, or higher dust levels may need more frequent filter changes.


Need a Visual Guide? 


If you'd like to see the process in action, Home Depot provides an excellent step-by-step guide and instructional video demonstrating how to replace an HVAC air filter safely and correctly.


Following a trusted tutorial can help ensure your filter is installed properly and your HVAC system continues operating efficiently.

A small maintenance task today can help prevent expensive repairs tomorrow.