A microfilter, also known as the cabin air filter, is completely separate and different from the engine air filter, though they basically serve the same purpose. Whereas the engine air filter cleans the air for your engine to "breathe" more easily, the microfilter cleans cabin air so that the passengers can breathe more easily.
The microfilter is placed within the heating, ventilation and air conditioning (HVAC) system. Air cannot enter through the car's air vents without passing through the microfilter. The paper filter traps contaminants, often with the help of an electrostatic charge or activated charcoal.
The microfilter is usually easy to locate. It is usually readily accessible through or under the dashboard, behind a panel. It is also often located just under the upper portion of the dashboard and accessible through the engine compartment.
In addition to creating a cleaner breathing environment for passengers, microfilters can also increase the life and reliability of electrical components because the filters limit the dust and debris that could harm delicate electronics.
