Plenum Chamber Water Drain, Checking
The water drainage from the plenum chamber may be impaired by deposits (leaves, various tree needles, etc.) accumulating in the water drain -arrow-. The water level in the plenum chamber then rises if the vehicle is taken to a car wash or if there is heavy rainfall. Water enters the heater and A/C unit via the fresh air intake and is blown onto the evaporator with the air by the fresh air blower.
If the water drains -arrow- on the left and/or right are dirty with leaves and tree needles, the water drain may freeze in the winter and water can no longer drain. After a short drive, the heat emitted from the engine and exhaust system melts the ice in the drains again and water may have drained off again before the vehicle arrives at the workshop.
If the plenum chamber cover -2- is damaged or incorrectly installed, water may enter the fresh air intake via the rain water drain channel -1-. This may result in complaints regarding an odor coming from the heater/A/C system and/or moisture in the vehicle interior.
The plenum chamber cover must be completely engaged in the windshield frame -3-. Refer to OVERVIEW - PLENUM CHAMBER COVER
Procedure
-- Remove the plenum chamber cover. Refer to OVERVIEW - PLENUM CHAMBER COVER
-- Check the water drains -arrow- for debris.
- The water must be able to drain.
-- Clean the dirtied water drains.