Vauxhall Astra - Windscreen misting problems?

[doctorwhen]

Time to "un-lurk" and seek the advice of the board instead of passively reading!

I have a problem with windscreen mist on my '96 Astra Estate (1600 petrol). I've merely "dealt with it" since I bought the car a couple of years ago, but driving down the M40 and suddenly going from clear screen to zero visibility in seconds has prompted some action.

I've had it happen a couple of times, always in the rain, and it happened for the second time on a quiet A road a week or so ago - I had to pull over and wait for it to clear. No amount of wiping would shift it. The inside of the windscreen was drenched - so were all the interior windows! Scary.

Window open - no change (except I got wetter!)
Heaters/blowers on full blast - nothing apart from a small clear area at the base of the screen.

With all the heavy rain of late, I decided on the previous occurence it may be a recurring problem, and ironically that "I wouldn't want it to happen on a motorway". So I did a bit of Googling and found that it is a common issue.

The information I found suggested that it might be a blockage in the outlet pipe for the drainage channel that runs under the windscreen. If this fills with water, the ventilation system apparently blows all this lovely water into the cabin.

So, before I set off on today's motorway journey, I located the pipe - a flattish, rubber pipe in the centre of the bulkhead at the back of the engine bay - and pulled out half-a-handful of black gunge.

I thought that would cure the problem, but it didn't. Driving along the motorway, luckily having slowed down due to torrential rain, the windscreen misted up in a matter of seconds again. Thankfully, I was close to some services and pulled off to wait for the rain to clear.

Has anyone else suffered this problem?

Has anyone tried any of those commercial "anti mist" products and do you think they'd help in such an extreme case of misting?

Is it going to be a nightmare job to move all the plastic guttering to check underneath and see if there's any more gunge?

With the current state of the wonderful British Summer, I think I really ought to get this sorted ASAP! I am going to email Vauxhall and see if they can/will help, so I'll post any useful response here for anyone else who may have this potentially lethal phenomenon.

Cheers all!

 

[Porker]

I had a 911 with a similar problem (also noted for poor ventilation). From what you have said it does sound like water getting inside the cabin. The usual cause on most cars is blocked drainage (as you suggested) and anti mist sprays can help but it is better to cure the source.

My only tip is that if you want to locate where water is getting in (and this may not apply in your case) use a light dusting of talc and any moisture ingress will leave a trail. This only works really if you have access. I was getting soaked carpets and couldn't work out where it was coming in. Later traced to rear sreen seal.

Sorry I don't know the Astra specifically.

 

[keyplayer]

Does your heater demist blow out hot or not, and is it blowing onto the screen? Could be your heat position selector at fault.

 

[TexMex]

Have you tried ramming something up the pipe (say a piece of curtain wire), to make sure it's clear all the way. You could also try pouring some water on the roof, with the bonnet open, to see where the run off is getting to. It may be a hole in the gutter at the back of the bonnet that has a leak.

I'm not that familiar with Vauxhall Astras so I may be talking gonads.

 

[doctorwhen]

Does your heater demist blow out hot or not, and is it blowing onto the screen? Could be your heat position selector at fault.

I have tried blowers on full both heated and unheated. Heated seems to move it fractionally quicker. I've also checked the "recycle" button is not switched in - so it's definitely "fresh" air that's coming in... just seems to be pulling in all the moisture, too.

If the blower is not on & ventilation switched to footwell only, the misting occurs more slowly, but it still happens.

 

[doctorwhen]

Have you tried ramming something up the pipe (say a piece of curtain wire), to make sure it's clear all the way.

No - the rubber pipe is pretty thin and I wouldn't want to try that.

Someone suggested using a jetwash to fire water "up the wrong way", which I might try.

I think, though, that compressed air (say, from a forecourt tyre inflator) might be a better option if I do have a leak... I don't want to use high-pressure water when water is a problem!

 

[securespark]

This sounds really dumb, but is the system on recirc?

This does not help. My wifes last car 92K Astra CD, was always damp & sweaty on the inside with recirc. Very difficult to deal with. Recirc in general is awkward - great for keeping CO & CH4 out (Ever gone past a sewage farm? Pooooooo!), but not good for condescension.

In my Skoda, I keep the screen vented, along with face vents, the outer two of which are directed to the side glass. Recirc is only on for minimum amounts of time, rest of the time fresh air is always coming into the cabin. Sometimes, I've even been known to throw all caution to the wind (!) and open a window, too!!

Daredevil!

 

[TexMex]

No - the rubber pipe is pretty thin and I wouldn't want to try that.

I was talking about the springy stuff you use to hold net curtains up. If it's too thin for this, no wonder it gets blocked.

 

[pipme]

The 'recirculation' switch may be 'off' but has the flap operated ? Are you actually getting fresh air in ? Operate the recirc with blower full on, you should hear a change in tone as the flap actuates.
I reckon this is where your problem lies.
If you have a misted window and your heater set highest temperature blowing on windscreen with only small area demisted ... You must be on recirculation !! Warm moist air onto cool window = condensation

 

[mrjeffs]

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