CLK W209 windscreen demister problem

[Linux_cat]

Hi all,

Wondering if someone could help. I have a 2003 clk 240, and recently my windscreen demister has become intermittent and basically useless.

It’s the dreaded click from the dash, the demister blows on the windscreen then after a few seconds switches to
The footwell and stays there.

I have tried the reset by pressing the demist and the recirculation buttons. The lights flash but remain flashing, and although it temporarily blows the windscreen it then goes back to the footwell.

I have tried taking the head unit out and reaching to the top left to pull out the wires from one of the motors, although I managed to do it the problem remained.

Im now guessing it’s a whole dash out
Jobby, however wondering if there is another potential fix? (I’ve heard you can
Jam the flaps into a particular position).

Any and all insights will be greatly appreciated.

 

[rifiki]

Anything on youtube?
I have aircon all the time, set the temperature and distribution a that's it
It is very rare to use demister button.

 

[horatio]

I had to change a linkage arm on mine which required nearly all of the dash to be removed. I wouldn’t panic about “dash out”, it sounds scary but it isn’t. It comes apart nicely and isn’t a nightmare if you’re patient!

I would see if you can isolate where the problem motor / link is - it might be possible with Star IDK. I found the dodgy one by cycling the motors with the dash partly out (keep the top panel connected if you do this because it apparently sets the airbag light off).

If you have the comfort HVAC with the digital screen you have 10 stepper motors rather than 6 so it’s more complicated I’m afraid!

 

[horatio]

By the way, not to start mission creep but I fitted the facelift switches while I did the stepper motor as it was zero additional effort seeing as the centre cage was out anyway. The pre facelift buttons are pretty nasty.

 

[Linux_cat]

So I managed to do a fix, although it’s not perfect. So if you take the centre piece trim out (one with the heating controls, air bag light, heated seats etc) you can press the demister and air circulations buttons together (hold for 5 seconds until they flash). When the air flow is blowing on the windscreen unplug the connector to what seems to be the fan control (see picture) this will keep the air flow in place and it will not go to your feet. Draw back is, I think
I have lost the AC. For me it’s fine, I’m in the UK and the demister is quite key in these winter months. I’m hoping that the car just needs an air con recharge but I’m guessing what I have unplugged is the temp controls.

 

[daveyjm1969]

Hi which plug did you disconnect to get the demister working. Understand all except that does it work fine .cheers