2008 e class:- Smell from centre vents

[wadeyblue]

Smell from centre vents on e class w211 2008 year.
I have an annoying musty smell from the centre vents in my 2008 e class 280. 47k miles.
If I keep the vents closed then it is ok but as soon as I open them when heater is on it comes back.
When the vents are open the smell is at its worst when going round a roundabout (no I am not having a laugh).
So far it has been back to Lexus Garage I purchased car from and they replaced the filter next to the blower fan.
Next I again returned it to Lexus dealer who passed it on to Mercedes dealer who claimed to clean various bits inside system? They then injected the mould spray but when this cleared I still have the musty smell.
My warranty is up soon and I will have a go myself but first has anyone got a plan, sketch, drawing etc of the heating valves and air ducting on this vehicle so I can pinpoint the most likely source of the smell.
And has anyone else come across this problem on a reasonably young e class?
I would really appreciate any help offered or suggestions made.

 

[st4]

I suspect a drainage channel could be blocked?

 

[Stratman]

Yep, the drain from the A/C evaporator is blocked. It's probably a rubber tube which exits underneath the car somewhere near the bellhousing. The end will be blocked with road crud.

When the A/C is in use, moisture from the atmosphere will condense on the cold surface, just like it does on windows. It drips into a tray which has a drain tube to the outside world. When the drain gets blocked the water stays put and becomes a breeding ground for squillions of pongy bacteria.

 

[developer]

This refers to the straight six E Class, but Im betting the pipe is the same - may be worth a read.

The smell being drawn in was really strong because the water in the pipe couldn't get away and was rancid.

W211 E320 CDI windscreen drain - my fix - Mercedes-Benz Owners' Forums

 

[wadeyblue]

Thank you fo suggestions, I will give them a try.
I would have thought the Merc dealer would have checked for a blocked pipe???

 

[RobertoMercini]

Very similar issue with my C Class but I was just going to wait until I have the aircon serviced. Thanks all!

 

[wadeyblue]

Jacked up the car, got the 2 protective covers off from under engine and transmission.
Spent about 30 minutes under car looking for anything remotely resembling a drain hose or plug.
Found nothing.
Back to square 1
The suggestion seems accurate that a blocked drain could be the problem, but where is the drain on a E280 W211 year 2008??
Any photo would be greatly appreaciated.

 

[renault12ts]

Jacked up the car, got the 2 protective covers off from under engine and transmission.
Spent about 30 minutes under car looking for anything remotely resembling a drain hose or plug.
Found nothing.
Back to square 1
The suggestion seems accurate that a blocked drain could be the problem, but where is the drain on a E280 W211 year 2008??
Any photo would be greatly appreaciated.

Did you try what John suggested in post 4?

 

[Stratman]

The drain is part number 460 in the picture. Judging by its location I'd guess it exits over the bellhousing.

What are xxx in your VIN? WDB 211xxx

 

[wadeyblue]

Great diagram, just have to get to top of bellhousing now.
xxx is 220 ie WBM211220

 

[wadeyblue]

Not had time yet to try John suggestion.