Plenum Water Flow Direction and Cleaning
A large percentage of water will flow off the windshield area into the plenum chamber drain system and then down the outside on the plenum to the underside of the vehicle. To ensure that the plenum chamber water management system performs properly, the plenum water deflector, plenum chamber, and drains must not be blocked with debris.
In the graphic the arrows show the water flow direction in the plenum chamber and drains system.