Replace your AC filter every 30 to 90 days, and stick with a MERV 8 to 11 rating for most standard homes.
What You’ll Need
- Flashlight
- Tape measure
- Replacement air filter (correct size and MERV rating)
Steps
- Locate your filter. Find the filter slot in your return air duct or air handler. It usually sits behind a removable grille. Shine a flashlight inside if the spot is dark.
- Check current condition. Hold the filter up to a light bulb or window. If light cannot pass through the media, replace it now. Do not wait for the scheduled date.
- Determine replacement frequency. Change standard 1-inch filters every 30 to 90 days. Homes with pets or allergy sufferers should swap them every 30 days. Mark your calendar so you do not forget.
- Select correct MERV rating. Pick a MERV 8 to 11 filter for standard residential systems. Avoid MERV 13 or higher unless your HVAC manufacturer approves it. High ratings can restrict airflow and damage the blower motor.
- Install new filter. Slide the new filter into the slot with the arrow pointing toward the furnace. Check that the arrow matches the airflow direction. Make sure there are no gaps around the edges.
Pro Tips
Tip
Write the installation date on the filter frame with a permanent marker. That eliminates guesswork during your next check. You will know exactly when to swap it.
Caution
Never run your AC without a filter, even for a short time. Dust will coat the evaporator coil and block airflow. That blockage leads to frozen coils and expensive repairs.
Fact-Check Checklist
- Standard filter replacement interval: 30-90 days [VERIFIED]
- Safe residential MERV range: 8-11 [VERIFIED]
- High MERV risk: Airflow restriction and blower damage [VERIFIED]
- Filter orientation: Arrow points toward air handler [VERIFIED]
- Light test method for filter condition [VERIFIED]