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Discussion Starter #1
A frequent problem on older W209 CLKs is the occurrence of a repeated clicking/knocking noise that seems to come from behind the dash panel. If so, it is likely to be one of the several actuator (stepper) motors used to drive the air flaps controlled from the Climate Control system (a/c).
This clicking noise will start as soon as the ignition is turned ON and (generally) will not stop for some time.
To address all W209 CLKs built it is necessary to cover both versions of the Climate Control unit and this post will address Code 581b Convenience. This version uses 10 motors and has a screen and an in-built diagnostic system. This version could be fitted on W209 CLK sales worldwide.
To determine which motor is causing the problem is important as the access to some motors is relatively straightforward, while others are more time-consuming. There is no general rule. A high-end diagnostic check will identify the faulty motor. The first thing to view is the WIS drawing below showing the locations of all the motors on both the a/c designs. Having identified the probable motor, follow the procedures below to access the motor. The referenced additional procedures shown on the WIS pdfs below are not included in this DIY.

Attached pdfs below are as follows:
1. A32m2 (a)
2. M2/5 (b)
3. M2/6 (c)
4. M2/7 (d) Note: I believe that the WIS document title is incorrectly titled ‘except 581b’
5. M2/8 (b)
6. M2/9 (b)
7. M2/10 (e)
8. M2/11 (f) (g) (c)
9. M2/19 (f) (h) (i)
10. M2/20 (f) (g) (i)
11. Actuator motor locations 581a & 581b
12. 581b flap operation

Additional procedures referenced above:
(a) Remove a/c unit housing
(b) Remove instrument panel
(c) Remove cover below left of instrument panel
(d) Remove glove compartment
(e) Remove X-member under instrument panel
(f) Remove COMAND/radio
(g) Remove lower section of instrument panel on passenger’s side
(h) Remove lower section of instrument panel on driver’s side
(i) Remove ignition switch cable

continued on page 2
 

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Thank you Keyhole for taking the time to make a comprehensive DIY on this troublesome subject.
Am I correct in presuming that for we who follow the UK and have RHD cars ,,,that when looking at the diagrams, left becomes right and right becomes left ?
 

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Discussion Starter #5
You are correct. The WIS generally dodges this problem by referring to drivers side and passenger side.
 

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Keyhole, if you want, I can move this into the "Maintenance" sticky thread.
 

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Discussion Starter #8
^^^
Yes, please - I think that is a good idea. As time goes by these stepper motors are bound to become more troublesome.
 

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Keyhole or Rudney, do you know where M2/16 is located? A scan shows Component M2/16 (Left and right defroster flaps actuator) is stiff or blocked.

Along with M2/8 and M2/11 which your info shows, also come up as blocked or stiff / mechanical failure.

Thanks in advance.
 

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Discussion Starter #11
Keyhole or Rudney, do you know where M2/16 is located? A scan shows Component M2/16 (Left and right defroster flaps actuator) is stiff or blocked.

Along with M2/8 and M2/11 which your info shows, also come up as blocked or stiff / mechanical failure.

Thanks in advance.
Aah... you will not find it on this thread, as you obviously have Climate control Type 581a and this thread only covers Type 581b. Try this link:

https://www.benzworld.org/forums/c209-a209-clk-class/3015116-w209-diy-remove-install-actuator-motor.html

That post shows M2/15, M2/16, M2/21. I produced DIYs for both 5812a and 581b. Both should have gone into the C209 Sticky section, but 581a got overlooked.

Rudeney can fix that. :smile
 

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Aah... you will not find it on this thread, as you obviously have Climate control Type 581a and this thread only covers Type 581b. Try this link:

https://www.benzworld.org/forums/c209-a209-clk-class/3015116-w209-diy-remove-install-actuator-motor.html

That post shows M2/15, M2/16, M2/21. I produced DIYs for both 5812a and 581b. Both should have gone into the C209 Sticky section, but 581a got overlooked.

Rudeney can fix that. /forums/images/BenzWorld2/smilies/tango_face_smile.png
Thanks so much for the response. I will look over the links.
 

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Having taken my dash apart to get to m2/15 the vent flap had jammed itself. now it’s unstuck and back together but the actuator only moves when button to demist front screen is pressed. When you move the vent selection control it never moves, is this correct, don’t want to rebuild dash just to take it apart again at a later date. Seems it stays open all the time directing air to feet??
 

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Discussion Starter #16
OK. This thread is only about accessing the actuators. Vent flap control is something else.

This (slighty damaged) document for 581a from my WIS might help you understand what the vent flap control logic is supposed to do. m2/15 gets mentioned there.

a/c Type 581b is also included below.
 

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Hi Keyhole ,
I have a clicking stepper motor which I believe is A32m2 ,,,in the 581b convenience system.
A32m2 operates the air through the charcoal filter ,,which I never use anyway ,,but the 25 clicks every time I start is annoying.
I finally had a go at it today ,,,I have removed the glovebox and attached cup holder /trim etc,,,and I can see the blower and filter housing.

A32m2 is very difficult to reach ,,,your wis says to remove the AC Housing ,,AR83.30-P.5200Q

Could you please post this procedure so I can see how I am supposed to access this motor...I see it is very close to the blower intake ,,maybe I can reach it that way ? No ,I dont think so..
As a last resort , what would happen if I cut the wire to the offending motor, it seems to be the last one in the line,,,ie they dont have individual wires , but just one wire that plugs in to several motors as it travels along.but I'm not certain ?
Thanks again for posting the other diagrams.
Thanks in advance...
 

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Don't worry Keyhole ,I found it ,,,
Removing ac housing is a major major job....I don't think it will happen ,,,beyond me and would cost a fortune to have it done ,,and it would never go back together the same I bet ,

Maybe removing the upper dash panel is easier ?

I have to figure out another way to stop the ticking,,,,I hate to say it ,,cut the wire to the motor. ?
 

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I found a work around..thanks to Keyhole ,,an old post advising that switching the Activated Carbon filter on stops A32m2 from clicking on every start up.

Accessing A32m2 is impossible , unless you want to tear half your car apart,,,shame MB didn't design this unit with more thought given to future replacement of parts.

However , I found that switching it on stops the clicking ,,,so that means your air is always carbon filtered. I decided I don't need this and to improve airflow I have removed the activated carbon filters ,,so I have normal air all the time.

At least now I know how to remove the 6CD ,glovebox/cup holder unit ,the centre console, the upper console Comand and switch panels etc.

I am pleased I did not have to cut the wire ,,and best of all ,,no more annoying ticking...
 
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