shamrode

Hi,
I am new to mercedes and now that I am here I am never leaving. I just bought a 2009 C63 AMG and I am in love. Question; I have noticed only a couple of times that when I drive hard that there is a slight exhaust fume smell in the cabin. The a/c is in auto mode with the the air circulation function on. Is this normal? Just thinking now; perhaps while in auto mode the air recirculation may be overridden and canceled and this is why I smell it? Perhaps the occasional smell is normal. Thanks


P.S.
I am not nearly a mechanic but I added two pictures of the back left (facing car) engine corner. The "black box" sitting there is being held by only one clip because the other two broke. Could air be sneaking in through there? I believe the a/c fan is in the opening behind the black box.

QWKSNKE

I would say yes. That is going to be the climate control air inlet. There should be a cabin air filter someone there too

shamrode

In the left hand picture there is meant to be an external filter?

JRHolt

The cabin filter is accessed under the glove box so you would not see it from that vantage point.

Also, the fan and air inlet compartment is extremely dirty and looks like it has not been sealed off properly for quite some time. The threads on the shaft of the fan appears to be rusted as well.

I would replace the cabin filter and try to clean that area the best you can. I would also replace the broken piece to make sure you are breathing fumes from the engine compartment, that can't be very good for you.

I would check the heater and evaporator cores to see if they are dirty and need cleaning

shamrode

The fan is not rusted; just dirty. How would I clean it without taking it out? Some kind of spray? How do I access the heater and evaporater cores?



This flap hermatically closes I don't think air can get by it.

The piece that needs to be replaced is the whole plastic framework surrounding the openings because two of the three clips are broken and the plastic cover doesn't sit well.

JRHolt

Oh okay, that is good. Was hard to tell from the picture. I am not sure if you can see the cores when you remove the filter or not, just replaced mine recently but didn't look through the opening.

I believe that flap that closes is the recirculation flap that closes off outside air from entering the car.

Maybe just replace the broken piece and the try to wipe out the compartment the best you can. After you replace the filter, if there are not any bad odors, then you may be okay.

If you wanted to get the system flushed then you may have to take it to the dealership. Not sure if it is something that you can tackle at home or not.

I am at work on my laptop and do not have access to MBWIS at the moment. I can look up the procedure for you later if you wish or maybe someone else can chime in to give you some guidance on the subject



P.S. Just did some more research and here is a thread I found on the subject on a UK Forum: W204 Evaporator clean

I have attached a Service Bulletin that is contained in the thread that covers flushing the evaporator core. It involves drilling holes and and using plugs to close them up afterwards. Doesn't seem like it should be too difficult to do.

Good luck