There is no point in breathing dirty, pollen filled air. Cabin air filters reduce allergens and pollutants from entering the passenger compartment. A clogged filter can also reduce the volume of air passing through the air vents. Pelican carries a full line of filters to keep you breathing healthy.
If you're moving your heater knobs and nothing is changing your cables may be bad and not sending the information along. Make sure you have everything you need to keep you warm by replacing any faulty cables.