Fogging Up

Garvin

Member
Cambridgeshire
In this wet weather I find that, in the morning, the inside of the car feels decidedly clammy and the windscreen is always 'fogged up' on the inside. It also fogs up if I park up when it's raining and come back to drive it, say, 30 mins or so later. I have searched in vein for any leaks and the carpets are always dry! Are there common points for leaks or blocked drain tubes to look for or is this a common problem?
 
It's the time of year. All our cars are doing it. Use your air con as much as you can as it extracts moisture from the cabin. Also wind the windows down a bit when not using air con to get fresh air in and remove moisture .
 
The Z4 is far more prone to this problem than any other car I've owned. Looking around a number of forums it seems to be a BMW trait, and not just on the E89! May well be a poor design of air intake for the heating/aircon system with a plenum that doesn't drain sufficiently. I suspect that rain water sits at the bottom of the plenum and, via the 'fresh air' route/vents, creates a high level of humidity in the car resulting in it fogging up far too readily.
 
In my car, If the roof is ON so is the Aircon !

Apart from keeping the environment in the car correct, frequent use also maintains the lubrication of the compressor pump's seals and as Captainken has already said, make sure recirculate is not switched on.
(we've probably all done it at some time I would guess)
 
I keep the aircon on permanently, as I have done with countless other cars, and keep the recirculating off, as I have done with countless other cars, but this vehicle just fogs up after it rains far, far more than any other car I have driven. Even after long drives with the climate in the car controlled for hours, it still does it if it is/has been raining and reasonably cold outside. Just damn annoying!
 
Captainken said:
As well as Aircon on....make sure it is NOT set to recirculate as this will cause fogging

You learn something everyday , both mine have done this but this one seems to be worse than the previous one
 
Yep me too mines exactly the same I'm afraid ! Couple of mins with blowers on sorts it out but it is a little frustrating ! :thumbsdown:
 
mine dosent suffer from this and its outside all the time these days :-(

Make sure you hear the auto vents close after a period of time with the ignition switched off.

All BM's have this feature i think :-)
 
This is my second winter and have had no problems fogging.
But i do cover the car every night, as i park under a tree.

When i inspected the pollen filter i noticed a few bits of leaves dropped out. Bit suprised as i thought there would be a good size grill stopping that. When i lifted the bonnet an inspected that area where the intake is, i could not see how any large size leaves could get in. If you look lower down on the engine bulkhead, there is a little rubber flappy valve.
Looks like it drains water from the air intake area. Just make sure thats note bunged up with bits of leaves.
 
Nobodys going to say it? OK I will then....

Get yer roof down in a morning and crank your heaters and heated seats up lol!

Thats all :D :driving:
 
My E85 fogs up easily too. Seems to be part of the car's "personality".
As others have noted: cracking the windows a smudge or keeping the aircon on normally solves the problem.

Although there was one time ... I had been driving in a deluge for a couple of hours with windows shut tight and aircon on, and everything was fine. But then I had to open a window to pay a toll and the whole car instantly fogged up so badly that I could't see a damn thing (inside/outside temperature/humidity differential). It was pissing down in all directions so I had to keep the windows closed, and I could not find an aircon/de-mister setting that would clear it out quickly enough. Ended up crawling along for about half an hour with my nose glued to the windscreen trying to avoid traffic and other obstacles (there was nowhere to pull over and stop).

So yeah, I'd say the Z4 can be a bit touchy in the window fogging department. At least you're not alone.
 
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