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Steamy windows, heater matrix, air con...

Discussion in 'A4/S4 forum(B5 Chassis)' started by adbett, Apr 10, 2009.

  1. adbett
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    adbett New Member

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    Hi, got a bit of a problem with steamy windows inside a '98 A4 Avant 1.9TDi Had it for a while but now it's getting quite bad (funnily enough it didn't fix itself!). Car has air-con.

    I've trawled the threads to get a plan of attack but would welcome some more experienced opinions before attacking the car!

    Symptoms are steamy windows (most but not every time I drive the car), occasionally a smell (I think coolant) and dropping coolant level. Air con still appears to work (car gets colder). Plan is:

    - check drain hole under battery to make sure water isn't leaking in from engine bay etc. If everything looks good will assume matrix is leaking

    - short term fix is to disconnect the 2 coolant pipes that go into the matrix from the engine bay and join them together with short length of copper pipe. I won't get any heat in the car but I can at least keep using the car safely

    - buy and fit new matrix, any other seals / gaskets / parts that I will need or should replace as most of the dash will be out?

    - professionally discharge air-con before starting, Haynes manual also says to put air-con into "service" mode, what is that?? no mention in other threads

    all comments appreciated!

    adam
    #1
  2. dieselfitter251
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    dieselfitter251 Blow ma own trumpet?

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    I think the drain pulg is your best bet mate. Also, check the spare wheel well. For some reason, I always seem to have about 3/4 litre of water in there. It's not coming from anywhere like the rear washer bottle, (rear wash wipe not worked in 2years!), all rear door seals and everything are fine... bizzare!
    Anyway, check them out first before you start messing with the air-con, in fact I doubt it'd be the aircon, it works indepandantly of the engine colling system, (basically). You may have a slightly leaking rad. I had a slight perforation down by the drain plug, popped in some rad-weld about 18 months ago and it was fine.
    It all may turn out to be not that serious. Good luck!
    #2
  3. JohnC
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    JohnC Member

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    Adam - I know it's a long time ago now but did you ever get to the bottom of this? I have exactly the same steaming up symptoms. The plenum chamber is bone dry - as are the carpets - so no signs of blocked drains. CC warms up nicely and blows ice cold on LO so I doubt if it needs re-gassing, and in my case the coolant seems to be leaking from the bottom of the header tank (already replaced the cap). No sign of oil/coolant contamination but I know this doesn't necessarily exclude potential gasket leaks.

    I've just now replaced the pollen filter as it was pretty black and clogged (the car's due its annual service and the last filter has done 20k). Hopefully this will improve airflow a bit.

    Last month the fan blower motor packed up and I was driving around for a week or so during all that freezing weather with no fan until I could source a replacement. During this period the car naturally got a bit damp inside, but surely any residual moisture would've disappeared from the ventilation system by now? I do about 300-450 miles a week. Car is a '98 1.9TDi quattro Sport saloon with 185k miles.
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  4. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    Its something that seems to affect AC cars for some reason. If you run the AC intermittantly, the car will steam up when you turn it off. Must be condensation inside the heaterbox or something.

    If you run the AC all the time, it doesnt seem to happen.
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  5. JohnC
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    JohnC Member

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    Hi aragorn

    Thanks for the reply, but I think it's more than that. I've had quite a few cars with a/c and this goes beyond the usual bit of condensation you get when you turn it off. I've owned the car since 2006 and it's not done it before; I usually have the a/c off except when it's really hot and I've never had steaming up problems until now. Imagine it being permanently damp and humid outside and you've got the recirculate on with the a/c off, well that's what I'm experiencing pretty much all the time when it's colder than five degrees or so outside. I have to have the blower on full with the temp set to 'LO' to avoid condensation build up on the windscreen; if I adjust it up to 18 I get steam billowing out of the vents for a couple of seconds and this is enough to completely mist up the winscreen again. The side windows seem to be pretty badly misted up most of the time as does the rear window. Obviously having the a/c helps to dehumidify the air in the cabin and prevent the misting, but when it's too cold for this to work I'm often having to resort to wiping the inside of the windscreen every two minutes just to be able to see out. Help!
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  6. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    If your actaully getting steam billowing out, then it does sound like a leaky heater matrix!
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  7. JohnC
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    JohnC Member

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    And the only way to get to that is by removing the whole dash, right?
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  8. Matt82
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    Matt82 Active Member

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    a pollen filter can make a lot of difference, did it fix it?
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  9. JohnC
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    JohnC Member

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    No, it didn't unfortunately. It improved the airflow slightly but the long and short of it is that the air coming into the car is damp and misting up all the windows pretty quickly even if I have it directed into the footwells. When it's warm enough outside for the a/c to work it's not quite as bad, but obviously that isn't the case very often at the moment.
    #9
  10. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    i've no idea whats involved in removing the matrix, never taken that much of my dash apart before!

    Have you got a workshop manual for the car?
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  11. JohnC
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    JohnC Member

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    No I haven't, although I plan to get one. Up until recently it's only needed minor stuff doing.

    However, I did find THIS. :ohmy:
    #11
  12. Nitrospud
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    Nitrospud New Member

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    John C, I too have started having exactly the same symptoms.
    Bypassed the matrix last night (trust it to be 1'C this morning brrr...) and it's noticeably better.

    How are you progressing with it ?

    Steve
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  13. voteforpedro
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    voteforpedro Member

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    just hope it's nothing like the Mk3 Golfs.

    [​IMG]
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  14. Lee Goodall
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    Lee Goodall ..got my head together!

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    I've got exactly the same problem too!! Looks like the engine could be swapped in less time than it takes to change the heater matrix :(
    #14
  15. THE MONSTER
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    THE MONSTER Member

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    Did you (or anyone)want the How to Do it I have it somewhere..it will frighten you when you see all the Dash out bit like the Golf actually but this is A4..

    I have noticed there are over 760 views on this thread must be a BIG popular problem..
    Last edited: May 13, 2010
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  16. Lee Goodall
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    Lee Goodall ..got my head together!

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    I had a look at this guide (above) from earlier on in this thread and nearly cried :3sadwalk:

    Any other info would be useful cheers.
    #16
  17. THE MONSTER
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    THE MONSTER Member

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    Yes mate that is the one I have left/hand version but we get the idea..regular flushing or keeping an eye on things might prevent it..I also saw sometime back again American that some guy had rigged up a twin pipe system that he hooked up to the pipes and cleaned the Core out with a cleaning fluid..

    A REAL lot of gunge came out thick and black it was so he probably saved himself the trouble..

    Don't know if it would work if you have it at a later stage but it as to be worth a try when you see what's involved in replacing it because it's probably only the gunge that is causing the problem..
    #17
  18. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    Surely a bit of radweld would be an easier option, worked on my Mk1 Golf GTi
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  19. Lee Goodall
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    Lee Goodall ..got my head together!

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    Yeah it's got to be worth a go; I think I'll isolate the matrix from the system, give it a good flush and then stick some radweld in it. I really don't want to be pulling the interior to bits if I can avoid it to be honest.
    #19

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