GM Service Manual Online
For 1990-2009 cars only

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 below the arrows show the water flow direction in the plenum chamber and drains system.


Object Number: 2020387  Size: MF

Plenum Chamber and Drain Valve-Cleaning

The plenum chamber is located in front of the windshield and below the plenum water deflector.

  1. Remove the plenum water deflector. Refer to Plenum Water Deflector Replacement.
  2. Clean the plenum chamber, drains and the plenum water deflector of debris blockage.
  3. Flush the plenum chamber, drains and the plenum water deflector with clean water.
  4. Install the plenum water deflector. Refer to Plenum Water Deflector Replacement.