C209 CLK 320 Windscreen Vents Not Working

WindsurferCLK

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The windscreen vents have stopped working on my vehicle, of course as it's the coldest day of the year!!!

My footwell and face/side vents work when selected, and everything else seems to work well, however when I set the dial to the windscreen nothing comes out.

When I adjust the vent direction settings from the control I can hear a motor operating for about 10 seconds for each case (e.g. footwell, face, windscreen). I put the fan on its lowest setting otherwise you can't hear the direction motor(s?). I don't hear any clicking noises.

Any idea's?
 

Steve@Avantgarde

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You will need star to do this, but the heater box motors need renormalising as the first step. After that, it could be one of the vent flap arms have snapped. Dash out job on a CLK, not too bad to do though.
 

Uncle Benz

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The stepper motor is item 90, but the drawing is rubbish and doesn't show you where they go. You see the temp sensor, item 80 and the arrow? The defrost flap motor sits in the little vacant recess just above that sensor. The other picture shows the motor in that recess, but doesn't label it. There is another motor just below the item 80 too. It 'ain't that one. That is air blend temperature control iirc.

Now, to complicate things that picture is a left hand drive car. The motor is on the passenger side of the car, but the blower motor assembly makes access poor. It is dash out I'm afraid. No other way.

Definitely Star diagnosis first though. This is not something to get wrong.
 
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WindsurferCLK

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Thanks, I've got a diagnostic next week. Will see how it goes from there! I suspect it will be dash out regardless...
 

Oldspanners

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Thanks, I've got a diagnostic next week. Will see how it goes from there! I suspect it will be dash out regardless...
If you hear a click every few seconds on turning the ignition on for a few minutes it's either the stepper motor or the small plastic operating arm that's split.
On my W203 it turned out to be the motor but simply dismantling it and turning the drive wheel through 180 degrees and re-greasing cured it, although I did change the arm at the same time as it's not expensive.
Seemed like a huge job at the time but wasn't too bad at all had a lot more difficult ones.
I've tried to upload the info I found but the files are too big.
If you are interested perhaps there is another way.
 

rf065

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My CLK had a similiar problem but resetting the heating fixed it, worth trying before spending any money on it?

To reset heater flaps and actuators

Switch on ignition.

Press recirculated air and defrost buttons on control panel together for longer than 5 seconds.

The LED's in the defrost and recirculated air buttons flash alternately.

Wait until the LED's stop flashing (approx 30 sec) system set to defrost LED on.

Switch off ignition.

After 40 sec re start engine.
 
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WindsurferCLK

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My CLK had a similiar problem but resetting the heating fixed it, worth trying before spending any money on it?

To reset heater flaps and actuators

Switch on ignition.

Press recirculated air and defrost buttons on control panel together for longer than 5 seconds.

The LED's in the defrost and recirculated air buttons flash alternately.

Wait until the LED's stop flashing (approx 30 sec) system set to defrost LED on.

Switch off ignition.

After 40 sec re start engine.

Thanks for the suggestion, I tried that but it didn't sort it out.
 
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WindsurferCLK

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I've had a diagnostic tool connected this morning. It listed "left and right demist motor stiff or stuck".

Called my local Mercedes dealer, they said my car has 6 motors (according to their system) and stepper motors are £145 each.

Questions:
q1. Are there one or two motors for the demist flap(s)
q2. Do the demist motor(s) connects directly to the ventilation box without any arm / linkages?

So next step is to have the dash out to check it's the stepper motor at fault... not looking forward to that...
 

Uncle Benz

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One motor, acts directly on the shaft. No linkage.

Edit: I say that, but there might be a half inch long white plastic sleeve that connects the two, but you need the motor out to see it anyway
 

Oldspanners

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I've had a diagnostic tool connected this morning. It listed "left and right demist motor stiff or stuck".

Called my local Mercedes dealer, they said my car has 6 motors (according to their system) and stepper motors are £145 each.

Questions:
q1. Are there one or two motors for the demist flap(s)
q2. Do the demist motor(s) connects directly to the ventilation box without any arm / linkages?

So next step is to have the dash out to check it's the stepper motor at fault... not looking forward to that...
Here's a link to the heater controls it's an exploded diagram but will show all the components;
http://mb-teilekatalog.info/view_Su...&catalog=69M&model=209365&group=83&subgrp=035
The stepper motor on mine just required dismantling and moving the larger gear wheel through 180 degrees as one tooth had worn out as it only moves a few degrees either way. If it doesn't move at all ie. burnt out there are used ones on ebay.
Edit;
Have a look through this thread there are some pictures and links to diagrams that I can't upload as they are too large.
https://mbworld.org/forums/c-class-...per-motor-replacement-clicking-hissing-2.html
 
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Buderim11

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I have had the dashboard clicking since I bought my 2004 CLK320 petrol , on my car I am sure it is the windscreen demister that is clicking as the air is always blowing on the windscreen but mainly on the passenger side . The reset does not work as the flap just keeps clicking .
I am just confirming that I need to take the whole dash out rather than just the center console and glove box ?
EDIT.. I have the analog display so the 6 motor version with NO carbon filter.
 
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