defrost question w203

[mattuk]

Hi guys

Front windscreen in my car gets misty very bad when rain or cold. For example yesterday was raining all day and all my trips were with defrost mode all the time. For some reason I can get only half way defrost but visible enough to drive. All vents work but I have feeling that not strong enough. for example when car is cold vents blow strong air and is ok until car warm up. To get all mist out I have0 to open windows. Then it clear quick. Even with defrost mode on I shut windows up and after few seconds mist back again. What can cause it? Pollen filter is 6months old and I tried to reset panel

Thanks

 

[television]

Do the mats feel damp anywhere

I would check the drain pipes in the air intake, you have some of those pipes but not all

 

[whitenemesis]

Are you running with the a/c ON? This provides a drying action to the incoming air.

Do you have any dampness anywhere in the car? Footwell carpets, boot etc..?

Pollen filter may be new but if it is getting wet through blocked drains this will exacerbate the problem.

 

[mattuk]

Yes mats by passenger and driver side feel a bit damp but no wet , all drain pipes under the Bonniet are clear I cleaned them few weeks ago, after rain I can see water dripping underneath of car. Is there any more drain pipes?

No I don't run a/c but with ac off mist should go away I think?

 

[whitenemesis]

Yes mats by passenger and driver side feel a bit damp but no wet , all drain pipes under the Bonniet are clear I cleaned them few weeks ago, after rain I can see water dripping underneath of car. Is there any more drain pipes?

No I don't run a/c but with ac off mist should go away I think?

No, with a/c OFF you are just pumping more damp air into the car.

Try it with the a/c ON and you will see the difference. MB designed the system to run continuously, there are seals that can dry out if not used routinely. I never switch mine OFF, there is negligible impact on MPG

 

[mattuk]

I don't worry About MPG
Ok I'll try with ac

What about mats? If these are bit damp what that means?

 

[television]

The air con being on and just running at the normal temp without extra cooling cost you nothing in terms of fuel consumption, the compressor runs all the time anyway. Modern systems are very different to those in the 90's.

If any damp clean out those air intake drain tube in front of the screen

 

[whitenemesis]

I don't worry About MPG
Ok I'll try with ac

What about mats? If these are bit damp what that means?

Could simply be where passengers have got in with wet shoes! You need to check under the footwell carpet (pull it down from under the dash on the passenger side) and see if the underlay is damp also. If it is then you may have a drain problem.

 

[mattuk]

Ok so how many drain pipes is in w203? When bonniet up is one on each side then runs down where something like sponge and water is sucked there and also there are two in center. What is best way to clean these drains out? Can u say how do u do this? Or is there any stuff to clean?
Also one more thing which could be related to this. When I drive car I can smell fumes from other car going on the front of me, and also windscreen washer and all oil,rubber burns is it normal to theesee cabin filters? Or my one is bad and doesn't do the job anymore even if is fresh?

 

[mattuk]

update

hi

i checked mats again and no sorry these mats don't feel damp, just normal.

i flushed some water in drains and runs fine. doesn't look cloged. i can see water dripping underneath of car.

what else is cabin filter, turn up to be very dirty. huh is only few months old and i just covered 3k miles but was dirty so it could be that. i cleaned up and looks like brand new now so keep fingers crossed.

what else... i run climate control reset with two bottons while engine was running and didn't stop for 2 minutes so i switched engine off and started to drive. what does it mean? i heard that it could be damper problem or something?

and the worst thing after i run car i noticed some fluid on lower cover:-(
it looked like coolant but i checked all up and nothing dissapeared from expansion tank.all hoses stone dry as usual. it looked like from under of radiator...after few minutes all dried up. it occured first time to me in this car.if it could be leaky radiator then fluid/water should drip all the time right?
or maybe it comes from air con compressor? air con not working but doing 2 buttons reset could run it for test and splashed fluid out through leaky seal?

 

[whitenemesis]

Have you tried just running with the aircon ON? Leave it on for a long journey and see how the windows clear/mist up

 

[television]

When you run the Aircon, water will run out of the bottom of the car and out of the heater box drain, it is from the evaporator and normal

 

[mattuk]

i am not running air con due to empty system.i saw some kind of fluid under radiator where engine is no under car

 

[whitenemesis]

i am not running air con due to empty system.i saw some kind of fluid under radiator where engine is no under car

Information that might have been pertinent at the start of this thread?? Try getting your a/c functioning correctly then post the effects on the misting windows!

 

[mattuk]

Ok
Will post back when rain comes ;-)

 

[mattuk]

Hi

I am digging this thread out again.every time when cold or rain all Carr gets foggy inside. Running a/c clears mist quick but once a/c off mist comes back. When I stop in traffic, I can't see anything.

I know that a/c should run all the time to help but it shouldn't mist with a/c off all the time.
Carpets dry, cabin filter clean.


Also the other day I noticed water on windscreen from inside! - strange.

Any ideas? Water drain blockage?

 

[whitenemesis]

Carpets may be dry but have you lifted them and checked the insulation underneath?

 

[mattuk]

Do the mats feel damp anywhere

I would check the drain pipes in the air intake, you have some of those pipes but not all

Is there any way to remove these drain pipes ? Or I have to poke wire and keep cleaning until is all clear?

 

[whitenemesis]

Net curtain wire is good to clear the drains.

 

[anyweb]

i had the same crap experience with demisting of the front windscreen on my W203 and I assumed that it was due to the non functioning fan directional issue (you know, the click click click you hear on some W203's when the plastic flap lever breaks)

i never did get that problem resolved as someone crashed into the car and i got a replacement,

that said, it was the worst demisting I ever had to deal with, so is yours clicking when you start the car ?