Breathe fresh air again! As an important part of your car's heating ventilation and air conditioning (HVAC) system, the microfilter should be replaced every year or 10,000 miles. If the microfilter (cabin air filter) becomes clogged it can reduce the blower output and lead to odoriferous emissions.
The cabin filter is often overlooked but it should be changed periodically. Old cabin filters can let dust, dirt, and allergens, and undesirable odors into your car's interior.