Demist not working problem

[alexman]

I've had this problem since I bought my Z4MR a year ago.

Especially if its cold (and wet like this morning), I have the fans blowing slightly outward (toward me) on a cold temperature whilst driving. Then this morning the screen started to mist up. In every case where this happens, if I put demist on, it starts to blow the screen with hot air and only clears a tiny section on each side low down and DOES NOT clear the entire screen. This is in contrast to another Z4 I've been in where demist clears the screen in 4-5 seconds!! Trying demist on a different temperature makes no difference (of course).

Also, if I'm generally driving and have some air blowing on the screen (set to blow up rather than outward toward me), it seems to mist the screen up rather than prevent it from misting.

If I put demist on and feel by the screen, it is blowing air hard from both sides. I had to stop this morning and run the screen down which you don't expect to need to do when you've got a supposedly amazing demister!

Could this be a problem with the alignment of the fans behind the dash so they are not pointing up enough or something? Anyone else had a similar problem?

 

[pvr]

You do need to have the airco on when you are doing that though, otherwise you are blowing "wet air" on the windows.

 

[EdButler]

Firstly, if youre from the US/UK why do you need your demister in the summer?! I need to use mine on 'full whack' about 2-3 times a year (and like you drive with it on very low) so this makes me believe your problem lies a little deeper...

What pvr says is mostly true, if you use the AC the pump de-humidifies the air which is more effective at de-misting. On many cars (especially if you dont use the AC much) however, if you switch the AC off, condensation builds in the evaporator core and often blows damp air for a while when the fans are next used. This is usually apparent in the mornings when youd been using the AC on the previous day.

If severe, it also sounds like you could have a water leak somewhere. Quite a common problem on some VAG cars is that water can leak through the scuttle panel beneath the wipers into the pollen filter and pax carpet causing misting a lot.

Id start by having a rummage around and feel if your carpets and pollen filter are wet. If not, do you use your AC a lot and this only occurr after leaving the car standing for a while?

 

[Medium Dave]

I had this problem when I first had the Z4. There was no air making it to the windscreen vents. It turned out to be the pollen filter was almost completely blocked. I was a bit sceptical as I would have thought this would affect every part of the air con system but they changed it and the problem went away. I guess that the pipe to the screen vents was affected more than the rest.