Noisy Air Conditioner ?? Stepper Motor Replacement / Clicking & Hissing
Newbie
Joined: Apr 2012
Posts: 8
Likes: 0
From: Phoenix, AZ
Clk 320
My "tick" was the little gear I mentioned earlier. I did replace the motor as well as I think it was a possible bad bearing or something in the motor itself. No more ticking. Look for a hairline crack in that gear.
Newbie
Joined: Jul 2012
Posts: 8
Likes: 0
XF SRT6
Got it figured out after the dash is back together. It's the gear on the blend that controls the passenger defrost vent is the culprit. Here I go again...
Newbie
Joined: Apr 2012
Posts: 8
Likes: 0
From: Phoenix, AZ
Clk 320
MBWorld Fanatic!
Joined: Nov 2001
Posts: 5,851
Likes: 196
From: Huntington Beach, Ca.
'17 Jaguar XF
You can just barely see the ribbon cable connector and unplug it with a long screwdriver if it bothers you. I did and haven't noticed any difference in defrost but I live in a temperate climate.
Newbie
Joined: Jun 2012
Posts: 7
Likes: 0
From: Baltimore, MD
2001 C240 6-speed
I just finished this repair and it went well. Many thanks to Racin_fool and liveniceguy for the text and pictures. It took me most of 2 days, not one hour like the experts.
I synched the stepper motors before putting it together, found the problem was fixed and there were no more bad motors or arms.
Put a dab of white lube on the shaft worked by the stepper arm, another use for the thin-bladed screwdriver.
The 90 degree turn T40 fasteners look like furniture attachment fixtures. Could some of the Mercedes engineers have come from Ikea?
It's so good to have no clicking sound and air on the feet. Thanks again for the great write up.
John
I synched the stepper motors before putting it together, found the problem was fixed and there were no more bad motors or arms.
Put a dab of white lube on the shaft worked by the stepper arm, another use for the thin-bladed screwdriver.
The 90 degree turn T40 fasteners look like furniture attachment fixtures. Could some of the Mercedes engineers have come from Ikea?
It's so good to have no clicking sound and air on the feet. Thanks again for the great write up.
John
Newbie
Joined: Aug 2012
Posts: 9
Likes: 0
2001
i had also got problem in my model after the first repairing of my car till now its ac is not cooling as cool as before it was i showed this to many mechanics but its not cooling much can anyone look up for my problem??
Newbie
Joined: Jun 2012
Posts: 7
Likes: 0
From: Baltimore, MD
2001 C240 6-speed
However, I also had a problem with almost no cooling. I bought an A/C pressure tester and hose and a can of R134A. The pressure was low before I put in the R143a. After the R134A, the pressure was up and I now have lots of cool air.
This is easy to do yourself if you follow directions including the safety directions.
Hope this helps,
John
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Senior Member
Joined: Jul 2011
Posts: 408
Likes: 40
From: Hawaii
2017 GLA 250, 2011 C63 P31 (p30 w/ lsd) (in repair), 2005 C230 Sport Eurocharged, 2003 C320~sold
Great BIG thanks to Racin_fool, liveniceguy and Wilsophia for the write up and
pictures!!!
I put together a PDF with the write up and all of the pics compiled with each other since I am going to be doing this myself.....enjoy!!! Unfortunately had to split it up into 3 files to post here.
W203 Air Conditioner Stepper Motor Repair P1 of 3.pdf
W203 Air Conditioner Stepper Motor Repair P2 of 3.pdf
W203 Air Conditioner Stepper Motor Repair P3 of 3.pdf
edit--here is the MB Wis doc for removing the center console
https://mbworld.org/wiki/images/e/ef...er_console.pdf
pictures!!!
I put together a PDF with the write up and all of the pics compiled with each other since I am going to be doing this myself.....enjoy!!! Unfortunately had to split it up into 3 files to post here.
W203 Air Conditioner Stepper Motor Repair P1 of 3.pdf
W203 Air Conditioner Stepper Motor Repair P2 of 3.pdf
W203 Air Conditioner Stepper Motor Repair P3 of 3.pdf
edit--here is the MB Wis doc for removing the center console
https://mbworld.org/wiki/images/e/ef...er_console.pdf
Last edited by krazzdav; Oct 12, 2012 at 05:09 AM. Reason: added wis doc
Newbie
Joined: Nov 2010
Posts: 6
Likes: 0
C240
Thanks a lot for the PDFs! Those are highly appreciated.
I was wondering if anyone knows of a way to disable to clicking temporarily, without having to take everything apart. I won't have time to do the whole fix for a couple of weeks, and the clicking is incredibly annoying.
If anyone has a temporary fix, please let me know.
I was wondering if anyone knows of a way to disable to clicking temporarily, without having to take everything apart. I won't have time to do the whole fix for a couple of weeks, and the clicking is incredibly annoying.
If anyone has a temporary fix, please let me know.
Senior Member
Joined: Jul 2011
Posts: 408
Likes: 40
From: Hawaii
2017 GLA 250, 2011 C63 P31 (p30 w/ lsd) (in repair), 2005 C230 Sport Eurocharged, 2003 C320~sold
Glad it is helping someone else out besides me 
Nope. The only other way would be to remove the connector to the particular module--some you may be able to get to by using a long screwdriver and only removing some panels. Have you tried turning off the AC/heater control? Not sure if this would make a difference....
Newbie
Joined: Dec 2012
Posts: 4
Likes: 0
CLK320 (W209)
A32m2
Firstly, hello to the board members. Secondly, this is an excellent thread. Thirdly, help!!
I've got a Clk 320 W209 with the dreaded stepper motor issue. A Star machine diagnosed:- M2/20, M2/11 & A32m2.
Today I ripped into the car and have fixed the broken lever on M2/11. Couldnt see anything wrong with M2/20 - not noisy.
A32m2 is however well and truely thumping away. I've got a replacement motor however it looks a complete pain to replace. So far I've stripped out everything including the upper dash. I can see the motor however the 3 screws are obscured where the bulkhead meets the windshield. Do I have to drop the whole Heater box to do this? If so has anyone done this as I can't find anything about it here. There was something about removing the windscreen wipers but I don't know if this is relevent. I could just disconnect the plug but that would be a bit of a wated effort considering I've got so much stripped out.
Any advice apreciated.
Thanks.
I've got a Clk 320 W209 with the dreaded stepper motor issue. A Star machine diagnosed:- M2/20, M2/11 & A32m2.
Today I ripped into the car and have fixed the broken lever on M2/11. Couldnt see anything wrong with M2/20 - not noisy.
A32m2 is however well and truely thumping away. I've got a replacement motor however it looks a complete pain to replace. So far I've stripped out everything including the upper dash. I can see the motor however the 3 screws are obscured where the bulkhead meets the windshield. Do I have to drop the whole Heater box to do this? If so has anyone done this as I can't find anything about it here. There was something about removing the windscreen wipers but I don't know if this is relevent. I could just disconnect the plug but that would be a bit of a wated effort considering I've got so much stripped out.
Any advice apreciated.
Thanks.
Senior Member
Joined: Jul 2011
Posts: 408
Likes: 40
From: Hawaii
2017 GLA 250, 2011 C63 P31 (p30 w/ lsd) (in repair), 2005 C230 Sport Eurocharged, 2003 C320~sold
Hey lecky and welcome....According to WIS it is very in depth---you have to remove the entire assembly from under the dash, disconnect the AC and Coolant.
there are 26 major docs (6mb) that I saved if you want to PM me for them. I attached a few of the most in depth/important ones here
This is for replacing the A32m2 'activated charcoal filter flap adjustment motor' (stepper motor)
Before you button everything up thinking the M2/20 is fine....connect your AC control and reset the motors--then watch all levers to ensure they operate smooth. I replaced the 4 arms and gears in the front because I had it apart already and some fell apart though it looked good and found a bad motor that had stripped gears in side.
Good Luck!!!! (I wouldn't bother fixing that motor and would just disconnect it!!...too much hastle haha)
If anyone knows any short cuts please chime in
1 ar83.10-p-2013q Remove_install activated charcoal filter flap adjustment motor.pdf
Remove_install air conditioner housing.pdf
Remove_install cross member below instrument panel.pdf
Risk of injury caused by performing testing or repair work on airbag or emergency tensioning ret.pdf
Remove_install instrument panel.pdf
Remove_install desiccant cartridge Side.pdf
there are 26 major docs (6mb) that I saved if you want to PM me for them. I attached a few of the most in depth/important ones here
This is for replacing the A32m2 'activated charcoal filter flap adjustment motor' (stepper motor)
Before you button everything up thinking the M2/20 is fine....connect your AC control and reset the motors--then watch all levers to ensure they operate smooth. I replaced the 4 arms and gears in the front because I had it apart already and some fell apart though it looked good and found a bad motor that had stripped gears in side.
Good Luck!!!! (I wouldn't bother fixing that motor and would just disconnect it!!...too much hastle haha)
If anyone knows any short cuts please chime in
1 ar83.10-p-2013q Remove_install activated charcoal filter flap adjustment motor.pdf
Remove_install air conditioner housing.pdf
Remove_install cross member below instrument panel.pdf
Risk of injury caused by performing testing or repair work on airbag or emergency tensioning ret.pdf
Remove_install instrument panel.pdf
Remove_install desiccant cartridge Side.pdf
Newbie
Joined: Dec 2012
Posts: 4
Likes: 0
CLK320 (W209)
Krazzdav,
Thanks very much for your pdf links, very helpful - especially the one about airbag safety. Extreme caution should be exercised when working around these components - or leave it to the experts!!
Well I can now say that I've managed to replace the A32m2 stepper motor. Infact, it turned out to be the round gearing cog that had stripped its teeth. replaced the cogs with ones I bought as part of a kit then also replaced the motor to be on the safe side - I'm never going there again!!
I did however manage to change it out without removing the whole heater box. If you disconnect the housing that connects to the pollen filter in the engine bay, you can press down on the blower motor housing which gives you an extra 1 to 1.5 inches of room. with a ratchet spanner and T20 bit, there is just enough room to get access to the 3 mounting screws.
Checked out the other components while i was there and replaced all of the accessible plastic with the bits from my kit. It still left a few components that are totally unreachable - thankfully working okay.
All went back together a bit quicker than it came apart. Now to get my SRS light reset!
Many thanks again for this very helpful thread.
Thanks very much for your pdf links, very helpful - especially the one about airbag safety. Extreme caution should be exercised when working around these components - or leave it to the experts!!
Well I can now say that I've managed to replace the A32m2 stepper motor. Infact, it turned out to be the round gearing cog that had stripped its teeth. replaced the cogs with ones I bought as part of a kit then also replaced the motor to be on the safe side - I'm never going there again!!
I did however manage to change it out without removing the whole heater box. If you disconnect the housing that connects to the pollen filter in the engine bay, you can press down on the blower motor housing which gives you an extra 1 to 1.5 inches of room. with a ratchet spanner and T20 bit, there is just enough room to get access to the 3 mounting screws.
Checked out the other components while i was there and replaced all of the accessible plastic with the bits from my kit. It still left a few components that are totally unreachable - thankfully working okay.
All went back together a bit quicker than it came apart. Now to get my SRS light reset!
Many thanks again for this very helpful thread.
Senior Member
Joined: Jul 2011
Posts: 408
Likes: 40
From: Hawaii
2017 GLA 250, 2011 C63 P31 (p30 w/ lsd) (in repair), 2005 C230 Sport Eurocharged, 2003 C320~sold
Great job lecky!!! 
Looking at the manual sounded like it was too crazy.
I am sure it says something like that for the front ones since I had to bend the motors a little to get to the screws around the bracing as well. I had some levers that were totally shattered, cogs with hairline cracks and a motor I took a part with the internal plastic gears stripped causing it to jump. Luckily I didnt have to get to any of the top ones!!
Welcome again to the forum...there are many knowledgeable people and lots of information here! enjoy
Looking at the manual sounded like it was too crazy.
I am sure it says something like that for the front ones since I had to bend the motors a little to get to the screws around the bracing as well. I had some levers that were totally shattered, cogs with hairline cracks and a motor I took a part with the internal plastic gears stripped causing it to jump. Luckily I didnt have to get to any of the top ones!! Welcome again to the forum...there are many knowledgeable people and lots of information here! enjoy
Newbie
Joined: Jan 2013
Posts: 1
Likes: 0
From: Chicago
2003 C32
Click click Click click Click click
Member
Joined: Dec 2009
Posts: 130
Likes: 0
2006 Volvo S40 T5 AWD 6spd
Post Facelift climate control
Does anyone know if the stepper motor problem was fixed when the interior refresh was done in 2005? The differences in climate control features between my 2005 C320 (analog controls) and my brother's 2001 C320 (digital controls) are many and his much more complicated.
MBWorld Fanatic!
Joined: Nov 2001
Posts: 5,851
Likes: 196
From: Huntington Beach, Ca.
'17 Jaguar XF
Does anyone know if the stepper motor problem was fixed when the interior refresh was done in 2005? The differences in climate control features between my 2005 C320 (analog controls) and my brother's 2001 C320 (digital controls) are many and his much more complicated.
Newbie
Joined: Jan 2012
Posts: 11
Likes: 0
From: Belgium
C32 AMG estate
Hi guys,
I just finished the repair using the instructions. Absolutely brilliant! So complicated, I would never been able to do it without! You have my eternal gratitude!
(maybe an improvement;
The screws behind the park brake release are very hard to reach with the lever in place. But if you unscrew the fuse terminal from the side, the cable is reachable just fine and you don't need to touch the screws while the release lever is still in place. Just unhook the cable and slide the lever out. Just my two cents...)
I just finished the repair using the instructions. Absolutely brilliant! So complicated, I would never been able to do it without! You have my eternal gratitude!
(maybe an improvement;
The screws behind the park brake release are very hard to reach with the lever in place. But if you unscrew the fuse terminal from the side, the cable is reachable just fine and you don't need to touch the screws while the release lever is still in place. Just unhook the cable and slide the lever out. Just my two cents...)
Newbie
Joined: Oct 2011
Posts: 7
Likes: 4
From: MA
c320 & c350
'04 c320 4matic. 90k miles.
I hear the "click, click, click.." for about 8 cycles after the car starts. It doesn't appear to be a broken linkage, because the flap fully opens and closes. The click happens when the flap quickly opens and slams the duct wall.
This is left fresh air flap, M2/19 for c320, the driver-side [USA] duct in the footwell, where the right side of duct almost touches the right wall of the footwell. The duct is oriented parallel to the floor.
I performed the HVAC resync and it didn't make a difference.
My question is: Is this a broken linkage? Since the flap fully opens and closes, can I fix the "click, click.." by attaching some adhesive-backed foam to the inside of the duct?
thanks in advanced for any feedback!
I hear the "click, click, click.." for about 8 cycles after the car starts. It doesn't appear to be a broken linkage, because the flap fully opens and closes. The click happens when the flap quickly opens and slams the duct wall.
This is left fresh air flap, M2/19 for c320, the driver-side [USA] duct in the footwell, where the right side of duct almost touches the right wall of the footwell. The duct is oriented parallel to the floor.
I performed the HVAC resync and it didn't make a difference.
My question is: Is this a broken linkage? Since the flap fully opens and closes, can I fix the "click, click.." by attaching some adhesive-backed foam to the inside of the duct?
thanks in advanced for any feedback!
Last edited by jcmajewski; Feb 23, 2013 at 04:51 PM. Reason: forgot to mention...
MBWorld Fanatic!
Joined: Nov 2001
Posts: 5,851
Likes: 196
From: Huntington Beach, Ca.
'17 Jaguar XF
I still think that's a bad linkage although your year <should> have the reinforced ones. Doesn't mean it can't have broken though in a different place than usual. Or the stepper motor is failing. The flap is moved by the linkage which is moved by the stepper motor shaft. If the flap arm was broken it wouldn't move at all.
Newbie
Joined: Oct 2005
Posts: 7
Likes: 1
2001 C320
Save the $80 and fix the linkage gears
Hi all,
I've been lurking around these forums for years. I purchased my C320 in 2004 and have been seeking out diy answers here for a long time. This weekend I went through the process of replacing my stepper motor arms. They have been broken for about three years. Summers have been a beeiotch because all of my cool air blows out of the footwell. So, my feet are freezing cold and from the knees up I'm sweating bullets.
Needless to say, once I discovered that the stepper arms weren't the only thing broken I was really distraught. I've seen a lot of you posting about the gear linkages that are part of the $80 kit. Unfortunately, you can't find these things without buying the whole kit (and who wants to do that?). So, I found a cheap and reliable way to fix them and decided to post it up.
If you have broken linkage gears behind your M2/19 and/or M2/20 stepper motors, have no fear. You can now fix them yourself using the attached instructions for about $2.50.
Let me know if you have questions.
I've been lurking around these forums for years. I purchased my C320 in 2004 and have been seeking out diy answers here for a long time. This weekend I went through the process of replacing my stepper motor arms. They have been broken for about three years. Summers have been a beeiotch because all of my cool air blows out of the footwell. So, my feet are freezing cold and from the knees up I'm sweating bullets.
Needless to say, once I discovered that the stepper arms weren't the only thing broken I was really distraught. I've seen a lot of you posting about the gear linkages that are part of the $80 kit. Unfortunately, you can't find these things without buying the whole kit (and who wants to do that?). So, I found a cheap and reliable way to fix them and decided to post it up.
If you have broken linkage gears behind your M2/19 and/or M2/20 stepper motors, have no fear. You can now fix them yourself using the attached instructions for about $2.50.
Let me know if you have questions.
Last edited by tdaily; Apr 29, 2013 at 12:11 AM. Reason: Edit: Adding picture
Newbie
Joined: May 2013
Posts: 1
Likes: 0
c32
Thanks very much for the write-up. I did this at the weekend, as a 2nd clicking had joined the long term one at the back of the dash. My culprits were A32m2 charcoal flap and M2/11 right footwell. The one right at the back A32 I could only disconnect, and the motor was bad on M2/11. I disconnected to get rid of the noise, and may replace if I go back in there.
Took about 5 hours to get the dash out and access the back stepper. The wiper assembly definitely does NOT need to come off on a RHD car, that was an hour wasted. About 10 hours in total for me.
All went together ok, I do have 2 screws left over as usual. Now the steering wont adjust up and down so I may have to go back at some stage.
But all is quiet when I start at least.
Took about 5 hours to get the dash out and access the back stepper. The wiper assembly definitely does NOT need to come off on a RHD car, that was an hour wasted. About 10 hours in total for me.
All went together ok, I do have 2 screws left over as usual. Now the steering wont adjust up and down so I may have to go back at some stage.
But all is quiet when I start at least.
