Because the cabin air filter helps clean the air that enters your cabin, you’ll likely notice when something is off. Some signs your cabin air filter is due for replacement include:

Weak airflow from the vents when using heating or A/C

Strange odor coming from the vents

Reduced air quality in the cabin

Unusual noise or whistling sound when using vents

Heating or A/C system don’t work as well as they used to

Like the engine air filter, you can visually inspect your cabin air filter to gauge how dirty it is. For vehicles that one, they are often located behind the glove box. Check your owner’s manual for instructions on how to access the filter.