Joseph Brown
Senior Member
Having just checked the plenum chamber on the W220 low and behold the drainage hole had dead leaves partially obstructing it. There are numorous references for the need to do this on the net, but below I quote Honest John from his review linked below;
"VITAL to keep ventilation plenum chamber drains clear of debris, or water overflows wetting carpets, vent blower motor and wiring loom causing shorts and sometimes necessitating a new loom. (The ventilation plenum chamber is the well in the bulkhead beneath the grille in front of the windscreen through which fresh air enters the car. It's open to the elements, so rainwater should flow freely through it, but won't if the drains either side are blocked. If that happens the rainwater will have nowhere to go except into the car.) Edit: And this is into the passanger footwell where the wiring loom is.
If buying used, CHECK ALL ELECTRICS and feel for damp front footwell carpets."
http://forums.mercedesclub.org.uk/newthread.php?do=newthread&f=5
Please see below for pictures and explanation of completing this easy task that took 15 minutes.
1. Locate the plenum chamber at the passenger side engine bay near the window
2. Remove the grate with a medium screwdriver by gently prising open each of the six slots in turn around the grill and pulling up slightly on the grill to release it on each occassion.
3. Inspect the drainage hole for blockages and remove them.
4. Replace grill and press down gently on each of the 6 catches to secure.
Job done
"VITAL to keep ventilation plenum chamber drains clear of debris, or water overflows wetting carpets, vent blower motor and wiring loom causing shorts and sometimes necessitating a new loom. (The ventilation plenum chamber is the well in the bulkhead beneath the grille in front of the windscreen through which fresh air enters the car. It's open to the elements, so rainwater should flow freely through it, but won't if the drains either side are blocked. If that happens the rainwater will have nowhere to go except into the car.) Edit: And this is into the passanger footwell where the wiring loom is.
If buying used, CHECK ALL ELECTRICS and feel for damp front footwell carpets."
http://forums.mercedesclub.org.uk/newthread.php?do=newthread&f=5
Please see below for pictures and explanation of completing this easy task that took 15 minutes.
1. Locate the plenum chamber at the passenger side engine bay near the window
2. Remove the grate with a medium screwdriver by gently prising open each of the six slots in turn around the grill and pulling up slightly on the grill to release it on each occassion.
3. Inspect the drainage hole for blockages and remove them.
4. Replace grill and press down gently on each of the 6 catches to secure.
Job done
