A car's engine air filter is routinely replaced during regular maintenance. But the cabin air filter is often overlooked, even though a dirty one can reduce HVAC performance. The cabin air filter in your car's HVAC unit filters dust, dirt, leaves, pollen, and smoke from air entering the cabin, helping maintain better air quality for occupants. A clean filter also helps the airflow in the AC vents remain strong and consistent, whereas a clogged one can restrict airflow and reduce comfort. The cabin air filter is typically replaced every 15,000 to 30,000 miles, or roughly once a year.
Of course, this depends on the types of roads you drive on. Dirt roads and regions with higher pollen or smoke levels may force you to change the filter sooner. Constant driving in city traffic or industrial areas could also result in the cabin air filter becoming clogged more quickly, as could driving with pets in the car as their hair is potentially drawn into the HVAC unit.
Most car manufacturers, including Ford, Mercedes-Benz, and GMC, recommend changing the cabin air filter every 15,000 miles.
The signs of a failing cabin air filter are quite evident, such as a musty or unpleasant odor when you switch on the car's AC. Reduced airflow might also indicate that the cabin air filter is clogged and needs replacement. If you hear an unusual noise coming from the AC vents, such as rattling or whistling, it probably means particles are obstructing the filter. Another symptom of a clogged cabin air filter is when the HVAC defogger fails to clear the windshield on foggy or rainy days, which could happen because the vents aren't delivering enough air to the windshield glass. The cabin air filter could also be the culprit if you notice more dust particles inside the car, as it isn't performing its function effectively.
Replacing a cabin air filter is relatively inexpensive and quite straightforward – that is, unless it's the Volkswagen ID Buzz. You typically need to remove a few screws, often located around or inside the glovebox; your user manual should provide details on its location and removal. From there, you replace the cabin AC filter with a new one. Pay close attention to how the original filter was positioned when you remove it, so you can ensure that the new filter is installed in the same orientation.
Like most modern car parts, you have a host of options when it comes to cabin air filters, including basic paper filters, activated-carbon filters, and HEPA filters, with the latter offering added protection against dust and smoke. Replace your cabin air filter on time, and your car will stay smelling fresh while your HVAC keeps blowing strong!