How to demist windscreem on W203?

Discussion in 'Electronics' started by stephenmercedes, Dec 3, 2018.

  1. stephenmercedes

    stephenmercedes Hardcore MB Enthusiast

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    2001 C240,W203. This morning ambient temperature was 2c. The inside of my windscreen badly needed demisted, yet on pressing the arrowed button (which I believe is the demister?) it took a good 10 minutes of me sitting on my driveway waiting for enough screen to become visible to safely drive off! My 23 year old Toyota clears the windscreen in a minute, maybe two at most.

    What is the quickest way to clear the windscreen on a cold winter morning?

    windscreen demist caption.jpg
     
  2. alecmascot

    alecmascot Hardcore MB Enthusiast

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    Is your thermostat working as it should ?
     
  3. MercedesDriver

    MercedesDriver Hardcore MB Enthusiast

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    I would suggest changing the cabin pollen filter and cleaning the filter housing, it always worked with my cars.
     
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  4. OP
    OP
    stephenmercedes

    stephenmercedes Hardcore MB Enthusiast

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    Yes, engine temperature has no issues

    Filter is brand new (well, a few weeks old) and housing vacuumed.
     
  5. PobodY

    PobodY Hardcore MB Enthusiast

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    Air con on to dry the air you're demisting with?
     
  6. OP
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    stephenmercedes

    stephenmercedes Hardcore MB Enthusiast

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    OK, can you confirm which button should be pressed to ensure this? (A/C is definitely working as I had new radiator, and recharge 4 months ago...)
     
  7. Ted

    Ted MB Club Veteran

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    Pressing that button should enable aircon.
    The aircon needs to be working to demist the screen quickly.
    On my clk it took anywhere from 2-5 minutes to clear at this time of year depending on ambient temperatures and humidity.
    You may also have a leak into the interior leaving some dampness in there. There was a lot of rain at the weekend.
     
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  8. GP801

    GP801 Hardcore MB Enthusiast

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    On some models (our SLK for instance) pressing the demist button gives full heat and power to the screen but turns the AC OFF! On the CLK which is similar to the 203 the AC stays on. We had an early 203 which had the same issues with demisting. Allegedly the recirculation function flaps were installed the wrong way round. Was told it was a known issue on some of the early cars.
     
  9. GP801

    GP801 Hardcore MB Enthusiast

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    Also the AC won't work if the outside temperature is low. Not sure of the exact figure but 4C rings a bell
     
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  10. OP
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    stephenmercedes

    stephenmercedes Hardcore MB Enthusiast

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    Odd that there are so many opinions on how exactly the ventilation system actually works in practice. The owners manual is very light on any such detail on what should be a very basic function. I guess Mercedes think the owner's chauffeur will sort it all out :D
     
  11. whitenemesis

    whitenemesis MB Club Veteran

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    A scrupulously clean interior windscreen also helps.
    That said my S203 '05 would take an age to demist, being diesel there was no heat to help but it was the same with the CLS, very slow and perversely it was always the passenger side that cleared first!!
     
  12. Stratman

    Stratman Hardcore MB Enthusiast

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    Driver's side the the fatherland ;)
     
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  13. John N

    John N Hardcore MB Enthusiast

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    Is this asking about the Front or Rear Screen? :confused:
     
  14. OP
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    stephenmercedes

    stephenmercedes Hardcore MB Enthusiast

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    Front LOL You can always drive off with a misty rear screen, most commercial vehicles don't even have one! :D
     
  15. John N

    John N Hardcore MB Enthusiast

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    The reason for asking was the fact that the Demist Switch you have highlighted looks like the Rear to me! The Front looks more like the same type, but the opposite side in your Picture! o_O
     
  16. GP801

    GP801 Hardcore MB Enthusiast

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    The button highlighted is for the front
     
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  17. Feeble

    Feeble Hardcore MB Enthusiast

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    I'd suggest there might be damp somewhere too. My car took ages to demist yesterday morning and it wasn't until I was halfway to work that I remembered I put a damp carpet in the boot that I used to keep myself off the ground when working on the car at the weekend. Doh. :wallbash:
     
  18. Rory

    Rory MB Club Veteran

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    I'd go for this as the answer. It's to stop the evaporator freezing.

    It can be a bit of an issue if you leave the a/c on all the time. Start the engine on a cold morning with the evaporator wet from last use, the a/c doesn't work due to low temp, so the system dumps damp air into the car.
     
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  19. Greenmanslk

    Greenmanslk Hardcore MB Enthusiast

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    Post deleted
     
  20. moonloops

    moonloops MB Club Veteran

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    Maybe stop pressing buttons and use a decent micro fibre cloth to wipe all the window insides ? :D

    Just don't leave the cloth in the car, dry it out at home.
     

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