Condensation Nuisance [Archive] - The 75 and ZT Owners Club Forums

Simon W

26th November 2006, 11:59

Is anyone getting condensation on the inside of the rear window (saloon)?

Since the weather turned coldish, mine gets very heavy condensation almost every night. It doesn't run onto the parcel shelf but the glass is a real pig to dry out. There's no rearward vision at all until it's been dried.

Any ideas how to prevent it?

Phil

26th November 2006, 12:13

Mines been doing it too, I was going to try a new pollen filter.

loupus666

26th November 2006, 16:32

Sorry chaps but my ZT does it even with a new pollen filter!

Ken

26th November 2006, 16:43

I think most cars does this, I put on the demister and it goes pretty rapidly

Ken

Rich

26th November 2006, 19:21

baxlin

26th November 2006, 21:34

Member "T-Cut" posted on the .org forum about this. His tip was to clean the inside of the windows with something like Mr Muscle glass cleaner, then using a slightly damp cloth, apply a very thin film of washing-up liquid to the inside of the window.

The detergent in it changes the strucure of the water apparently and stops it condensing on the glass. He said if you get foam, you've put too much on, but there were no instructions on how to remove the foam, so only put a tiny bit on!

Does it work? Well I did it this afternoon, and when I went to the car this evening, there was no condensation inside the windscreen ( I didn't do the other windows), like there had been over the last few days, and using the aircon didn't make it steam up, either, so I suppose the answer's yes.

BTW, plenum drain's clear, I check weekly.

Simon W

26th November 2006, 21:48

The washing-up liquid might be a way round it but the condensation shouldn't build up in the first place - there must be a design flaw somewhere in the ventilation system. Modern cars like this shouldn't fill up with water every time the weather gets a bit damp and chilly.

Keith

26th November 2006, 21:51

Using fairy liquid or something is an old motorcyclist trick for inside the visor it works ok for a while but can go milky after a while so is not ideal

JohnDotCom

26th November 2006, 22:17

Mine does it aswell :)

Also, the front is clear when I get in, the SECOND I start the engine, it mists up like mad???

Hitting the demist button normally clears the front screen in about 20seconds, still annoying/weird though!
The front more often than not is blocked drainage holes by the ECU & pollen filter which soaks up the water & gives that damp smell, and then blows damp onto screen. I dont know about rear screen as on the tourer estate the demister automatically comes on if temperatures cold or any other required conditions.

Simon W

26th November 2006, 22:45

The front more often than not is blocked drainage holes by the ECU & pollen filter which soaks up the water & gives that damp smell, and then blows damp onto screen. I dont know about rear screen as on the tourer estate the demister automatically comes on if temperatures cold or any other required conditions.

The saloon also has auto demist for the rear window.

For some peculiar reason there's usually more condensation on the rear than on the front. It might be something to do with the slope of it.

JohnDotCom

26th November 2006, 23:16

Thanks for info Simon, I thought as the problem appeared to be on Saloons that could be the reason.....but not realised it also had the auto functions.

JohnDotCom

26th November 2006, 23:19

You should see the Condensation problems all winter on the 400 series, if you dont have Air Con to clear it you have to drive with windows open a bit & F R E E Z E!

Simon W

26th November 2006, 23:43

Thanks for info Simon, I thought as the problem appeared to be on Saloons that could be the reason.....but not realised it also had the auto functions.

I don't know if all saloons have auto demist John - mine's got air con and it could be an intergral part of that. The dashboard has two yellow demister lights for the F & R windows and they both come on as & when they want to - or you can switch them manually.

baxlin

27th November 2006, 08:58

Simon, on my 2002 Conn SE with atc, the rear window demist comes on auto when temp dictates, and also when I select the front windscreen blower, but I've never had the front one come on automatically.

Can you give more detail of these 2 yellow lights on the dash, if that is you don't mean the lights in the two switches. If you do mean these two, how can I set the front demist to be auto?

Thanks

Malcolm

Simon W

27th November 2006, 10:25

Hi Malcolm

Yes I was referring to the lights in the switches. As for auto demist, I may have misunderstood what the system is doing - perhaps it's just the rear window that has auto demist and the front is manual, i.e. the windscreen light only comes on when I leave the switch in the 'on' position. The car's handbook says this (air con versions):

(Page 54) Defrost

Press the button at the beginning of a journey to clear frost or mist (the indicator switch illuminates and the defrost symbol along with the blower symbol appears in the display).

The defrost facility automatically activates the following:

The most efficient heater settings to clear the windscreen and front side windows.
The heated rear screen - for a maximum of 20 minutes.(Page 56) Heated Rear Screen

The heated rear screen will switch on automatically for 20 minutes if the engine is started when the outside temperature is less than 10ºC (50ºF). The heated rear screen will also operate automatically in association with the automatic temperature control.

To operate manually, press the switch (the indicator in the switch illuminates). The heated rear screen has two operation times, which are dependant on the outside temperature:

If the outside temperature is less that 10ºC (50ºF), the heated rear screen will operate for 20 minutes before switching off automatically.
If the outside temperature is 10ºC (50ºF) or greater, the heated rear screen will operate for 12 minutes before switching off.Hth

Simon.

baxlin

27th November 2006, 10:29

Thanks, Simon, that's what I thought, but I've had the car for 20 months now, and I'm still finding little gems of features that don't seem to be very well publicised (except on here of course!)

Simon W

27th November 2006, 10:55

Thanks, Simon, that's what I thought, but I've had the car for 20 months now, and I'm still finding little gems of features that don't seem to be very well publicised (except on here of course!)

Me too! I bought mine on Sept 30th this year and I still haven't figured everything out. For instance, what the heck is that little vent-type thingy on the dash next to the steering column?

crofts

27th November 2006, 11:22

Me too! I bought mine on Sept 30th this year and I still haven't figured everything out. For instance, what the heck is that little vent-type thingy on the dash next to the steering column?

I thought it was the speaker for my low line but think someone said it houses the sensor for the air con.

GreyGhost

27th November 2006, 12:11

Low line isn't fitted to my car so it must be the air con sensor.

It is indeed the A/C sensor.

Simon W

27th November 2006, 14:30

It is indeed the A/C sensor.

What's the little round thing on top of the dash GG? I think you've told me before but I've forgotten what you said.

GreyGhost

27th November 2006, 15:36

What's the little round thing on top of the dash GG? I think you've told me before but I've forgotten what you said.

That's the sunlight or lack of it sensor, works in combination with the internal sensor.

Simon

27th November 2006, 23:02

Just to clear up a few things about this condensation... (I hope!)

The rear screen will have more condensation forming on it because it's further away from the engine. ie. when you turn the engine off at night, the residual heat can help the front windscreen keep warm and therefore condensation-free for much longer than the rear windscreen.

Make sure you have the "air-recirculation" function switched OFF. In cars with ATC this should be auto-controlled (and will be off in colder weather by default). If you allow the air to be recylced in the car it will trap more moisture.

Obviously check plenum drains as water around the pollen filter will cause muchos moisture in the vent system.

If you haven't had your air-con serviced in a long time then it may not be functioning correctly. (For those who don't know, air conditioning works by removing moisture out of the air. So a well-maintained system will be working efficiently and correctly).

As a point of interest, I do not seem to be getting abnormal amounts of condensation on my (saloon) ZT.

One other point, it may be worth closing the rear-seat vents that emerge from the transmission tunnel. These blow cooler air and so it would be bennificial to close these in colder weather to help warm up the car quicker and help demist the rear windows.

Hope all this helps!

Simon W

27th November 2006, 23:22

Simon

27th November 2006, 23:45

It can't be anything to do with the distance from the engine since the condensation on the rear window is far greater regardless of whether the engine has been run or not.

Sorry to differ, but this can affect condensation build-up. Obvsiously, it doesn't in your case. :confused: Puzzling...

Would any of the other things be affecting it, do you think?

Simon W

28th November 2006, 00:03

Sorry to differ, but this can affect condensation build-up. Obvsiously, it doesn't in your case. :confused: Puzzling...

Would any of the other things be affecting it, do you think?

The distance from the engine would probably make a difference if the car has been used - but I can't see how it is relevant when the engine hasn't been run for several days.

Air recirculation is always off (I never use it).

Plenum drains are clear and ok.

I haven't had the air con serviced so I don't know if that would have any effect.

Closing the rear seat air vents would probably help.

The question still remains - why is a modern car like this getting such huge amounts of condensation in the first place?

Simon

28th November 2006, 00:10

The question still remains - why is a modern car like this getting such huge amounts of condensation in the first place?

Well, either the air-con isn't working efficiently or you've got water retention somewhere. :confused:

As a thought - Have you checked the seals on the rear window? I'm thinking that if water was ingressing through these then it could lead to it turning into condensation on the car. This may be a long shot but it's worth a check... :confused:

:lol:

Simon W

28th November 2006, 00:46

Well, either the air-con isn't working efficiently or you've got water retention somewhere. :confused:

As a thought - Have you checked the seals on the rear window? I'm thinking that if water was ingressing through these then it could lead to it turning into condensation on the car. This may be a long shot but it's worth a check... :confused:

:lol:

It should be able to cope without the air con. The window seal seems ok.

We're talking a lot of water here. It's equivalent to a very heavy frost on the window, only it's on the inside and it isn't frozen! When it's there, you can't see anything at all through the glass. Rearward visibility is nil.

:(

crofts

28th November 2006, 02:32

It is indeed the A/C sensor.

Knew as soon as I typed it that GG would show up. Must be murphy's law....... or something. Got to admit it does look like a speaker grill though, doesn't it. Just as well then that I didn't put my fist through it when that NAUGHTY WORD-NAUGHTY WORD-NAUGHTY WORD-NAUGHTY WORD-NAUGHTY WORD-NAUGHTY WORD- woman kept telling me " to make a U turn when possible" ! :D

Simon

28th November 2006, 07:22

It should be able to cope without the air con. The window seal seems ok.

We're talking a lot of water here. It's equivalent to a very heavy frost on the window, only it's on the inside and it isn't frozen! When it's there, you can't see anything at all through the glass. Rearward visibility is nil.

:(

Granted it should be able to cope without the air-con. I was thinking along the lines of that if there was a lot of water (which there is) then the air-con can help tp remove it. Similiarly, if the air-con is faulty could it be causing water to build up in the car? Y'know, maybe the aircon drain pipes are blocked?

We need someone with even more techy knowledge on here to cast some light on this mystery. I think we've exhausted all the obvious answers. :confused:

I'll have a think during the day about this and let you know if I come up with any ideas! ;)

Teflon

28th November 2006, 07:54

My wifes Daewoo recently suffered the same problem - a huge amount of condensation in the back. Last Saturday I found the cause - a passenger in the back seats had failed to properly close one of the rear windows. It was only open by a tiny fraction with no actual gap to speak of, but fully closing it cured the problem.

May not be the cause here, but it's always worth checking the obvious just in case.

Regards,

Cliff

Simon W

28th November 2006, 08:57

Good suggestion Cliff. I just checked and they're all wound right up.

mantianak

28th November 2006, 17:12

I don't get much condensation on the backscreen, and normaly if there is then there is also some on the front.
When I turn the engine off I hear a little motor buzz and what sounds like a valve closing from inside the vents. I'm guessing this is some kind of valve to stop dampness entering though the vents?

Also I had a lot of condensation on the front windscreen a while back and thought nothing of it untill I realised how often I was topping up the water. A thermostat housing seal had a crack in it and was leaking small (then soon large) ammounts of water onto the engine block/manifold. In turn I guess the water vapour would be sucked into the air ways and condensed on the screen.
Got it fixed and no condensation.

Simon W

29th November 2006, 02:36

I've never heard a little motor closing the vents. The only one I've heard is the headlight adjuster.

I don't think there's any moisture coming from the engine bay either.

Nick Hoare

29th November 2006, 15:59

I always seem to get a misted up rear screen on my saloon in cold and damp weather but soon clears with the aircon on

Simon

29th November 2006, 16:42

So, if you're rear window seals are fine, have you checked everything for water ingress. It may sound pedantic but if having somewhere for moisture to move freely (like the open window suggestion) could be the cause of your problem.

If you haven't already done so I'd check every possible avenue for water/moisture ingress (that little pannel behind the rear three-quarter glass, boot seals, door seals, sunroof and sunroof drainage channels, drainage channels in general, to name but a few).

It seems obvious (to me, anyway) that the build of water on the rear screen is because moisture is getting in the car somehow. :confused:

The only other solution is a bit far fetched and is something which couldn't possible happen... or could it?! I think I'll keep this one to myself as it's too far fetched to be actually happening... :o

Simon W

29th November 2006, 19:11

Yes I've searched everywhere for signs of water entering but I can never find any clues.

What is the far fetched mystery cause ??

Simon

29th November 2006, 19:55

What is the far fetched mystery cause ??

Ok. Now, everyone may laugh at me - so I'm prepared for the barage of rotten fruit and veg.... :target::nastypc:

This theory does have a genuine scientifc background to it though...
Anyway, here go's:

The water on the rear screen is caused by an electrostatic charge builing up on the heated screen elements causing water molecules in the air to become attracted to this charge and therefore 'sticking' to the rear screen.

The electrostatic charge could be caused by something gone amiss in the car. An example would be an friction-induced charge building up and being stored in the heated screen elements. When the car is being driven then the heaters, and vent system etc will eventually clear the water but when these systems are not operating the water has chance to reaccumilate again.

An electrostatic charge would not necesarilly show up as a fault with the cars electrical systems. I would think the only way to test this theory is to wire up a potentiometer (volt meter) across the rear screen elements to a ground source (common ground for the cars electrics or a litteral ground ie, your houses' earth point. I would suggest but I'm not overally sure - you could test both).

I told you this was far fetched.... :o

mantianak

29th November 2006, 21:22

I've never heard a little motor closing the vents. The only one I've heard is the headlight adjuster.

I don't think there's any moisture coming from the engine bay either.

Maybe the little motor isn't for the vent but it sure sounds like it. The noise I hear sounds like it's from the vents and it definitaly isn't the lights. The sound lasts about 3-4 seconds followed by something like foam or rubber slowly rubbing together.
What ever it is I wouldn't mind knowing as mine seems to be the only one making this noise.

Simon

30th November 2006, 13:30

I think you're using a bit too much rocket science.

Mind you, here is a picture of water molecules being attracted to the electrostatic charge (actual photograph of a Rover 75 rear window):

:group:

And here is a picture of a single water molecule (actual photograph):

:drool4:

:laughing2:

I did warn you about it being a very extreme theory! ;) :D

Teflon

30th November 2006, 14:07

What ever it is I wouldn't mind knowing as mine seems to be the only one making this noise.

Mine does it too. I have also assumed it was some kind of ventilation valve closing.

Cliff

sratansi

20th January 2011, 09:40

leeg3910

20th January 2011, 11:26

mine was doing this before christmas and the windows were frozen inside but i just put down to extra moisture in the car from getting in with snow on your boots as the floor mats were really wet, everythings fine now the weathers a bit better

sratansi

20th January 2011, 13:39

for some reason its now taking ages to demist the front windscreen, im sure i dont have any leaks in the car, maybe my AC needs regassing?

Nigel1516

20th January 2011, 17:18

sorry to bring an old thread back to life again...

the windscreen on my connie over the last week or so has been steaming up everytime is start the car now days, and for some reason its not clearing up as quickly as it used to do. anyone with an idea what could be wrong ?

Just reading this thread as mine has been doing this too for the last few days. Frozen inside on windscreen & rear window. Was starting to get concerned as I did the plenum drains a couple of weeks ago, and did the spyhole mod at the same time. Thought I may have done something wrong. Its a real pain sitting in the drive for 10-15 minutes before I can leave for work. I have checked in boot well for water ingress, but this is dry. Any suggestions please ?

Nigel.

Villa Villan

20th January 2011, 17:44

Same here with the windscreen and a wee bit on the rear glass too.

Cheers
Tony

Jules

20th January 2011, 17:51

sorry to bring an old thread back to life again...

It's good to revive old threads, it's keeps the topics more concise!

Possibly the Cabin exhaust vents (behind the side boot linings) are iced up or blocked. :shrug:

Also try parking the car the way round to normal!
The glass facing away from the sun always gets misted the most.
The morning rising sun will clear it.

Nigel1516

20th January 2011, 18:15

Possibly the Cabin exhaust vents (behind the side boot linings) are iced up or blocked. :shrug:

Not seen these as yet Jules. If blocked how would you suggest to clean them ?

Nigel.

Ragman

20th January 2011, 18:16

My rear screen was condensating badly - 6 out of 8 screen clips broken. screen out new clip, screen back in, now a lot better but not perfect

Jules

20th January 2011, 18:23

Not seen these as yet Jules. If blocked how would you suggest to clean them ?

Nigel.

Remove side linings (easy on a saloon) and have a look.
Also while you're there, check boot area for dampness & leaks etc.

On subject of Condensation I bought a Mini dehumidifier last year for my stock sales cars which aren't in regular use yet.
Absolutely superb bit of kit. (can draw a litre of moisture out of the air of an unused car that is left out in the open)

cymry

20th January 2011, 18:41

It's good to revive old threads, it's keeps the topics more concise!

Possibly the Cabin exhaust vents (behind the side boot linings) are iced up or blocked. :shrug:

Also try parking the car the way round to normal!
The glass facing away from the sun always gets misted the most.
The morning rising sun will clear it.

Hi Jules

Morning rising sun? Where you are? (Oh sorry forgot, you're above low cloud level)

I'm having the same problems with my tourer. No damp smell, plenums done by you last year but windscreen icing & badly misting on inside. I can live with the misting but trying to de-ice the inside with a scraper (don't want to use smelly de-icer spray inside) is a real pain. I've used intensive glass cleaner but no difference.

Oddly about 2pm if the car is standing for an hour or so after a short run, on starting up again it mists up (screen was clear when I got in); demist button quickly clears it. Perhaps its my warm personality (or maybe halitosis with a sensitive screen?)

:rant:

GT Courier

20th January 2011, 18:53

Could be worth checking the door seals?

Jules

20th January 2011, 19:00

A scientist/theorist will be along soon to give us the run down on Condensation!
Last week I swapped 2 75's round from their normal parking spaces.

Guess what the condensation has swapped over from the Silver 75 to the Black ZT!

Any meteorology buffs out there been monitoring the relative humidity in the last month as I suspect it's something to do with that.