W211 Steams up- why?!

[jon_viola]

Hi

My 53 plate w211 estate keeps steaming up in even the slightest bit of rain. I've changed the pollen filter. None of the carpets are wet and yet unlike any car I've had before its a real issue.

Any suggestions?

Thanks

Jon

 

[Deleted member 55947]

Try running the aircon, it'll act as a dehumidifier

 

[steve333]

As above-if your already doing so might be worth checking if it needs re-gassing or has a leak?

 

[Dieselman]

You shouldn't need to run the aircon as the ventilation and heated air will remove the moisture.

As you have changed the pollen filter check that the airbox isn't getting damp, the fan is running at decent speed and that the rear exit flaps are allowing free passage of air.

The problem might be that the aircon internal drains are blocked so there is a build up of water under the evaporator.

 

[redbaron]

It is leaking or has a blockage... or you havent cleaned the windows in 10 years

 

[Colin_b]

Aircon degraded, and heating set for recirc?

 

[jon_viola]

A/c works fine ie runs cold.
This does reduce the misting but as has been said it shouldn't make any difference. Recirc not on.

Fans work in all speeds an the area underneath the intake appears dry.

The car uses no water so no leaks in the matrix I guess.

Where are the rear exit flaps on an estate?

Thanks!

Jon

 

[wadeyblue]

And what are the rear exit flaps?

 

[Troon]

This does reduce the misting but as has been said it shouldn't make any difference. Where are the rear exit flaps on an estate?

No, it should make a difference, but shouldn't be necessary if everything inside the car is dry, including you.

Early cars, up to about September 2006 (shortly after the facelift) have a dew point (taupunkt auf Deutsch) sensor in the HVAC inlet. It's the white thingy in the inlet in the picture.

I have no idea what it does, but if it's keeping the recirc shut when the humidity is low enough perhaps it's faulty?

The rear flaps are behind the rear wheels, under the bumper; you can also get to them from inside by removing the boot side trim. See second picture: they're at the bottom of the image. They are loose rubber louvres to let the air out.

 

[Troon]

It's the white thingy in the inlet in the picture.

Hm. Not sure what happened to that picture, which was there briefly then vanished. Here it is again:

 

[GP801]

How long have you had the car? Is this a new problem? I mention it because we had a W203 that did exactly this. Dealer could not work it out until someone realised the system had been assembled wrongly at the factory so it was in recirculation mode as default.

 

[jon_viola]

Ah now that sounds interesting! I do get some whistling sounds sometimes and I'm never sure whether the recirc works or not.

The car is new to me.

 

[Troon]

Ah now that sounds interesting! I do get some whistling sounds sometimes and I'm never sure whether the recirc works or not.

From memory, I believe you can see the flap working. Open the bonnet, remove the pollen filter box as in my pic and look inside: you should be able to see the fan (attached pic from developer215 on the other side). Now press the recirc button and the view of the fan ought to be blocked as the recirc flap shuts off the exterior air inlet that you're looking through.

I don't have pictures for the 211 (might take some next time I'm in there), but here's what it looks like on the Mk3 Mondeo, and I think the recirc flap is conceptually similar on most cars.

 

[jon_viola]

Ok will do.

This might also cause my diesel Exahust smell...

 

[bigmacplease]

Air con will definitely stop you steaming up as previously mentioned.

 

[jon_viola]

So my recirc works fine. The housing was slightly off on the filter but shouldn't cause the steaming.....

 

[Major774]

Does it steam up when you use air con?

 

[brucemillar]

There was a time I would have been proud to have my car steam up.

 

[jon_viola]

Nope doesn't steam up with a/c on....

 

[rascalmaster]

S210