windshield fogging up
 

hey.. i dunno but the windshield in my c240 does not want to stay clear.. it is always fogging up... what is the correct setting to enable the defroster to work at its best?? Is there a trick to this??



[Edited by BmwTek on 02-03-2001 at 08:31 PM]

Hi:
The AC on my 300E was not very intuitive - I had to read the manual to correct some wrong assumptions on my part. My controls had a defrost, EC, and O button which I figured out correctly. The remaining 2 buttons each had arrows pointing up and down. I assumed the one with the black up arrow and white down arrow meant "Heat or cool the feet area", and that the button with 2 white arrows meant "heat/cool all areas". Wrong! Turns out that the first one means "normal operating position", and the 2 white arrows mean "temporary position to dehumidify windows, switch back to normal (black and white arrow)position when clear"!!! I wonder if something similiar is going on with your controls.

A Foggy Day In Olde Mercedes Town...
 

Wow, small world, ain't it? I was just pondering the same dilemma. Not about fogging up, but about proper operation of the climate control! The deal is this, you shouldn't EVER have the system shut off except " in case of bad odor or automatic car wash". And I'd like to think that we are all too sophisticated to use an automatic car wash!:rolleyes:

The rest of the time, it should always be on! To completely defrost the windscreen, you need to press the button with a picture of the windscreen on it. To defog the windscreen, you press the button with two white arrows on it, as JCE already pointed out. But then, you should go back to the either the "normal", or "economy" setting as soon as possible. If you still have an owners manual, read up on this stuff! ;)

One other thing, when my Aerostar had a problem clearing the windscreen, and the problem actually worsened using the defroster, I found that the culprit was the heater core, which had just died! :(

[Edited by longston on 02-03-2001 at 09:14 PM]

Check to see if the AC compressor is coming on when you turn on the defroster. It should operate when in the defrost mode.

BMWTek:

I thought I was alone. My C 240 has the same problem. I leave for work at about 5:00am every morning, and during these cold winter months, my windshield, side wondows and rear glass all fogged up. I have tried all settings, and found that:

1. the defroster setting work best,

2. the "Auto" setting is also good, but the defroster setting is more effective.

But I try to use them least as possible, because at either settings, they are very noisy. Also, they would leave no warm air coming down for my feet, leaving my feet freezing cold.

In conclusion, I found that the climate air circulation system used in the new C-Class is very weak.

Johf

The fogging up has happened to me on 4 american made vehicles........ and I ended up putting heater cores in. A very small pinhole leak that was pretty hard to even smell coolant from. Anyway, just another possibility for the windows being constantly fogged.

Make sure the recirculation mode is off (I dont think you can turn it on when in defrost or economy mode), this can really fog up you windows when it is left on long enough. Also if your a/c system is non-functioning and you still cant get the windows to defog, just crack a window about 1/2" this usually works. If you are really having problems there is antifog stuff on the market, I have never tried it so I dont know how well they work. Another possibility is the a/c compressor isnt kicking in because it is too cold outside, the a/c compressor on my Integra does not kick in when the ambient temp is around or below about 35 degrees.

Yesterday I read a review in my local newspaper on the C-240. One of the things they mentioned was the windshield fogging up...uhhhmmm.....Maybe we should get a pole of how many people, with the new C's, have that problem. I know Larry has one.

my experience is that you need your compressor
running whether you're using the heater or the
a/c, to avoid clouding your windows.

this happened to me last summer when the a/c
is on and then all of the sudden my windows fogged
up. took a while for me to trace the problem.
turned out i had a defective belt tensioner that
tipped off the clutch of the a/c. I thank steve
brotherton, tech of this forum for the advice.

hope this helps. try to do a search, belt tensioner.
my car is an 89 300E.