When taking the ASE G1 test you might run across a question like this:
Technician A says poor output from the air ducts in the dash and floor could be caused by a restricted cabin air filter. Technician B says the restriction could be caused by a recirculation door that is closed.
Who is correct?
Technician A is correct.
Even if the recirculation door or flap was stuck in the open or closed position, the air would not be restricted. A new cabin air filter is something many motorists need, but often don’t know it. The cabin air filter (CAF) is not a well-known or well-publicized filter. Close to 90% of late-model cars and trucks now come factory-equipped with a cabin air filter, but the original filters in many of these vehicles have never been changed!
How important is the cabin air filter? A plugged cabin air filter can restrict airflow through the heater, defroster and air conditioner. The filter prevents dust, pollen and other contaminants (down to 1 to 3 microns in size and smaller) from entering the passenger compartment. For allergy sufferers, this is a good feature to have.Filters that have a layer of activated charcoal and even baking soda to trap odors and other pollutants, making for a more pleasant driving experience in heavy traffic or when passing hog farms, soybean processing plants and other sources that generate nasty odors. Activated charcoal can even reduce the levels of carbon monoxide and oxides of nitrogen from the exhaust of other vehicles, which can be high in heavy traffic. The concentration of these pollutants can often be several times higher inside a vehicle than outside, which can affect driver reaction time and alertness. So regular CAF replacement can also have a safety benefit. This video is sponsored by FRAM.
