Cabin ventilation

[zcacogp]

Chaps,

Having just completed a 300-ish mile journey this weekend in foul weather (the windscreen wipers saw every setting other than 'off'), I have been reminded of the poor cabin ventilation of my S2. It seems that air can come in fine ... but not get out. Condensation forms readily on the inside of the glass (particularly if you have damp clothing on when you get in), but won't clear fully unless you open a window or the sunroof slightly.

Consequently, we did the whole journey with the sunroof slightly ajar. Not necessarily a problem, but a feature none the less.

Talking recently with a fellow forum member about this (ChrisG - Hi Chris!) it sounds like I am not alone in this problem. He spoke of the fact that the heater fan labours without a window open as the air pressure in the cabin builds up. Opening a window allows air flow, and the fan speeds up.

Chris described the air flow through the car to me; air flows into the cabin, and out through the vents along each side of the boot lid. From there it comes back, forward, inside the rear wings, and into either the cills or the back of the doors (through those door vents in the B-pillars).

However, from there it doesn't go anywhere. There are no vents out of the cills (apart from tiny drain holes along the bottom), and equally no exit vents in the doors.

So, apparently by design, the cabin ventilation is flawed. Air comes in, but doesn't get out.

Is this really the case? And, if so, is there any way that the cabin ventilation can be improved? (Apart from creating holes somewhere in the bodywork; maybe those rusty cills have their upsides after all!)


Oli.

 

[Riverside]

There are exit vents in the front of the doors, you can see them when you open the door fully.

Personally I raise the temp to 24, fan on 2 & that does the job with just me in the car, or fan on 3 with a passenger. tbh I'm a smoker so I usually have the window open a crack anyway. Big condensation inside the car suggests water ingress somewhere.

Until about a month ago it was my only car (for about 5 years now). I've always considered the heater, heated mirrors etc to be the more practical parts of the car, nice to own something old enough to be interesting but still new enough to have useful 'modern' stuff like this. Mine has heated seats & cruise too.

I love way the the dirt streams over the car when it's been driven a long way in poor weather, so much more satisfying to clean off than the vertical streaks when it's just been sat in the work carpark all day []

 

[zcacogp]

Sc0tty. No, no water leaks (that I am aware of.) There is very little condensation problem if everything in the car is dry (although there will always be a bit of condensation as exhaled air is slightly humid), but if any damp does get into the car (getting in with a damp jumper after having walked to the car in the rain for instance) then the resultant condensation is very slow to clear away, unless you open a window or sunroof.

ORIGINAL: Riverside

There are exit vents in the front of the doors, you can see them when you open the door fully.

Personally I raise the temp to 24, fan on 2 & that does the job with just me in the car, or fan on 3 with a passenger. tbh I'm a smoker so I usually have the window open a crack anyway. Big condensation inside the car suggests water ingress somewhere.

...

I love way the the dirt streams over the car when it's been driven a long way in poor weather, so much more satisfying to clean off than the vertical streaks when it's just been sat in the work carpark all day []

That is helpful, thanks. I'll check those exit vents from the doors carefully and make sure they are clear. Although having the window open a tiny amount is enough to eliminate condensation on mine as well, so I suspect that's why you have never had a problem with it.

Absolutely agree about the dirt streamlines. One of the most satisfying things about a long, fast run in bad weather is to see the patterns produced on the bodywork by the dirt desposited. I particularly like the ones that start off near the top corners of the windscreen and curve towards the centre of the roof, across the sunroof and wiggling off the back of the car. Setright had an excellent passage in his book "Drive On!" about this sort of thing; I must dig it out again ...


Oli.

 

[david924s]

I presume the recirculation valves (or flaps) were not closed otherwise it will steam up as you are recirculating the same air from within the cabin. I would echo what everyone has said my S2 none aircon will clear any condensation from damp clothing etc within minutes then keep the cabin clear on any length journeyand the fan does not slow down or speed up unless I alter the speed so maybe you door vents are blocked or the heater is stuck on recirculation. Or there is damp somewhere you haven't fouond yet

 

[zcacogp]

I read somewhere that the flow is as Chris says, and as Riverside adds that there are vents in the door leading edges , but also that the airflow over the sides of the car creates a low pressure area down the leading edge of the door which draws the stale air out. Seems the panel gaps are there for a reason! So it sounds like the answer is to drive faster []

As an afterthought, it might be worth checking that the plastic membrane behind the door card is fully attached and undamaged, as I guess it seals the door interior from the cabin.....

ORIGINAL: Riverside


There are exit vents in the front of the doors, you can see them when you open the door fully.

 

[Gordon Attar]

You should nt have a problem unless as I've never had the problem in any of my Porsches

- except when there was a leak that was not wetting the carpets but lifting them the sound proofing was soaked.

- other time the valve was stuck on recirculating and not venting externally through the rear.

Problem usually is to much hot air and not enough cool air!!!!!!!11

 

[Diver944]

I would bet it's the recirc flap stuck closed too. I've never had a misting problem no matter how far, cold or wet I've driven

 

[Riverside]

ORIGINAL: Diver944

I would bet it's the recirc flap stuck closed too. I've never had a misting problem no matter how far, cold or wet I've driven

That could explain the symptoms but I don't think it can stick closed. If there is a problem with either flap gravity will tend to pull them down (allowing the fan to draw external air).

I replaced the wiper mechanism last winter & had to take the heater fan cover off - the two big vacuum servos either side of the fan housing control the recirculate flaps, lifting them up to close the external inlets. Could be that there is a spring in there to hold them up (that's missing on mine) but I don't think so.

 

[zcacogp]

Interesting. I don't think it's the recirc flap; whenever I press the recirc button I can hear a change in note from the heater fan. Suggesting that something is changing as a result ...

More investigation needed methinks.


Oli.

 

[Hilux]

ORIGINAL: Diver944

I would bet it's the recirc flap stuck closed too. I've never had a misting problem no matter how far, cold or wet I've driven

Agree

 

[peanut]

this is an interesting thread Oli.. I have exactly the same problem every winter in my S2 although I most definitely have a big leak in my car and a big condensation problem

To be honest even with the window right down and the sunroof up I still cannot see anything out of any window. As fast as I wipe them they mist up instantly. It is really dangerous to drive . What the hell is going on ?

I have also noticed that the fan speed picks up noticably when the windows are opened .

I have been thinking about buying a small portable air/con /dehumidifier to leave in the car but I cannot get a mains lead to it because of an access lane between the house and car.

My car used to have A/C fitted . The previous owner removed the entire system from the car.

I have always thought that the severe condensation was due to something the previous owner cocked up.

To be perfectly honest I have never really fathomed out the heater and A/C settings. I just twiddle knobs and shove levers at random

I have noticed that every time that I start the car there is a loud whirring noise behind the dash heater vents ? anyone else notice this?

 

[jmelhuish]

Ive been using one of these http://www.frost.co.uk/item_Detail.asp?productID=9456&frostProductName=Air%20Dry and it does a great job

 

[jasonp]

ORIGINAL: zcacogp

Interesting. I don't think it's the recirc flap; whenever I press the recirc button I can hear a change in note from the heater fan. Suggesting that something is changing as a result ...

More investigation needed methinks.


Oli.

hiya oli, as you know i am not technical but my small damp patch was a leak traced to a crack in the plastic sunroof pipe, if you need to listen or see another s2s vent/heating system in action to help you discover if you have a problem or not then i am local and i could pop over or you over to me, please mail me if i can be of use, regards jason p

 

[peanut]

ORIGINAL: jmelhuish

Ive been using one of these http://www.frost.co.uk/item_Detail.asp?productID=9456&frostProductName=Air%20Dry and it does a great job

wow thats a really neat solution. Thanks for the link I'm ordering tomorrow.

 

[robwright]

+1 f or me. Don't have the problem but can't be bad while she is wintering on the drive me thinks []

 

[zcacogp]

Chaps,

Thanks again for your replies. I have yet to do any investigation of the issue in question (dark evenings and cold nights discourage me from poking around with the S2 once I have got home from work) but I doubt I have a leak. There is no dampness anywhere in the car that I am aware of, and there is no more condensation than to be expected when those in the car are dry. Hence, while I am sure they are wonderful thing, that sock-thing from Frost wouldn't be necessary as there is no excess moisture to remove. (Having said that, I'd be fairly confident that thing is pretty much just an old pair of wooly stockings with some Silica Gel in it, which is very cheap stuff to buy. £10 for that shouts "rip-off" to me ... )

The problem with condensation occurs only when wet things are placed into the car. Damp coats, rained-on jumpers, wet sailing gear etc, all produce huge amounts of condensation on the windows - condensation which you'd expect to be cleared by the heater, but which doesn't clear unless a window or the sunroof is opened.

I take the point about the recirc flap being jammed, and I'll investigate this. However I am doubtful this is the answer either. When I press the recirc button there is a change in airflow (you can hear the note of the heater change) and the air quality changes. Good example this morning - I was stuck in traffic behind a diesel lorry, and fumes were getting into the car. I pressed the recirc button and the fumes stopped coming into the car and the problem didn't get any worse. This would suggest to me that air from outside the car gets into the car under normal conditions, but this is changed when the recirc button is pressed.

At the moment, the most likely candidate in my mind is the exit vents in the front of the doors, as Malc (Riverside) suggested - thanks Malc.

Peanut, sounds like you have a similar problem to me. Interesting that you had air con but removed it; I wonder whether that is relevant? I do know that air con systems have very clever mechanisms to remove moisture from air (I think they are called 'drier units', but don't know enough about them to know whether the 944 system had them fitted), so I wonder whether there is one of those which is releasing moisture back into the car, or similar.

Jason, that's a kind offer - thank you. I don't think it will be necessary, but I will bear it in mind. Thanks again.


Oli.

 

[peanut]

Oli are you going to do any work today ? or do you just go in to surf lol[]

 

[zcacogp]

I'm ignoring that comment Nick. I'm too busy to type a reply ... []