Originally Posted by ants_oz

To those who think the filter is installed correctly - that air enters from the top and flows down past the filter. I suggest you check your facts.

Air flows in from the plenum UNDERNEATH the filter - that is why all the leaves etc collect in the bottom of the plenum. Air flows UP through the filter, and into the interior ducting.

Take the unit apart and check it if you don't believe.

On the attached diagram, air flows IN via the grilles (left and right) indicated approximately by No. 14 (for the right hand side of the vehicle). Down via the deflection ducts indicated by no's 5 and 6. This directs the inlet air down from the grilles, UNDERNEATH the filter carrier/plenum roof (no 3). The floor of the plenum (no 1) is where leaves etc collect.

Air then flows UP through the filter, into the main plenum (no 3), and out the back through the sealed openings (seals are no 11) into the vehicle interior ducting and heater radiator (etc).