One of the most common indications that it is time to replace the cabin filter, is a moldy or musty smell when the heat or air conditioning is on. The musty odor would smell like a wet towel left in the car for days. This is because pollutants, dust, mold and grime build- up on the filter and turns the filter to a source of pollution inside the car. A dirty cabin filter can make the air inside the car even more polluted than the air outside.  

The other most common sign that it is time for a new cabin filter, is a weak air flow out of the ventilation system. Often drivers confused reduced air flow in the AC with a mechanical problem in the car’s AC system, while it is likely a simple and inexpensive cabin filter replacement.  Clogged cabin filters add more pressure on the AC blower motor which can impact the blower.