barnesC240

Just got mine all fixed up. My guy said it was a really common problem in the W203. Cost to fix $726.34

Glyn M Ruck

Sound like you have two problems. A broken flap actuator arm & a dry fan/blower bearing.

Improved/strengthed arms were only fitted late 2003.

2subway

I just read through all the pages of this thread and I'm beat! It was a very good read but after reading it all I'm still left wondering.....SO.....I went outside tonight and ran the sync test just for the heck of it. Afterwards I ran my AC system through as many different settings as I could think of.
This is what I came up with:
When I did the sync test I could definitely hear the clicking sound from the topside of the dash (center as if it was directly beneath the grille area).
I could hear and feel how all the air was cycling during the sync test.
I never felt any air come through the defrost vents.....
I can say that the floor area vents were blowing air driver and passenger sides as well as going through the cycle of being cut off from blowing air.

When I stopped the test I ran the AC manual mode:
When I turned on defrost no air came through the vents for the windshield but there was air coming through the floor vents.
When I selected the face vents they all worked and everything else was closed.
When I selected the floor vents they worked and everything else was closed.
When I selected the top vents (defrost vents) there was no air to be had but there was air coming through the floor vents......

So am I right to say that my defrost motor and/or the link is broken?
Do you know which one this is? Is it one of the easier motors to get to?

Thanks for the thread, I'm about to read it again! I know some of you mentioned the defrost problem.
Henry

NYFlapjack2

My car (2002 C230K cpe) was hit & miss to the lower foot well air flow (seemed always off) to the upper dash defrost (was fluctuating on of off) and the "sync" would never stop searching the stepper motors limits. Had the tel tale clack snap sounds behind the radio too, each day at start up for a brief period too...

From reading here diagnosed as my M2/15 stepper or arm was broke, and yup found under head unit and major center dash removal. I took @ 7 leisurely hours to R&R that arm and stepper (I had both parts new in advance, arm socket was broke) ...I bet I could do it under 3 hours now...but I didn't try for time...just the $$$$$$ savings satisfaction and no dash, console or other interior damage.

Go here and look down ... see the W203 HVAC PDF for great help explaining the HVAC stepper units & details:
http://www.buellwinkle.com/howtos.html .....

Sounding like your M2/16 stepper motor/arm is the area effected? I believe a MB scan (or carsoft-i didn't have mine yet then? You in Syracuse I'd let you try mine) can tell which one is bad.... $$$$$

mleskovar

From your troubleshooting results I would say you are correct.


I agree with NYFlapjack2 that it is probably the M2/16 motor or linkage (see link he posted). I believe you must remove/lift the upper dash to get to this part....which involves removing center and lower dash first. Major work.

2subway

Thanks for the response I've tried to seek out a DIY dash removal but no success. Do you know of one existing on this forum?
By the way I forgot to mention that the clicking is only happening during start up for about 1-2 minutes then stops for the entire time the car remains on.
Thanks again,
Henry

mleskovar

Not for the top dash that I'm aware of. There is one for the lower and center dashes in the first sticky on this forum.



When the car is first turned on the footwell flaps cycle and air is blown in to clear the cabin. That clicking you hear is most likely a crack in the actuator arm that's allowing the stepper motor drive shaft to rotate inside of it. You may have two bad linkages....are you sure air never goes through the defrost vents?

2subway

Mleskovar.....Ok, I went through the sync test again and YES there is air flowing through the defrost vents ONLY during the sync test. Any other mode of AC/Defrost does not allow air to flow through. I uploaded a short video of the clicking sound along with a visual aid to boot. http://youtu.be/2V1CRJdBFqE

I could physically see the defrost vent opening and closing throughout the sync test.

So, I'm kind of confused at this point since I first thought that no air was coming through the defrost vent. I can also feel air coming through the foot well just fine on both driver and passenger sides. Any ideas?
Thanks for the troubleshooting help,
Henry

mleskovar

That means the defrost motor/link is OK. You're lucky. Does a big blast go through the defrost vents or just some air? It should really be forceful in the defrost mode.

I haven't heard that sound but that could be because of your mic/pickup. The flicking wand is interesting and seems to point at the defrost vents being the culprit though. But I doubt it.

Yes but do they ever close? Maybe the majority of the air is being directed through the footwell vents instead of all being directed to the defrost vents when it should be? The footwell link arms are the "usual" culprit probably because they cycle every time the car is turned on. It's hard to tell where the defective flap/motor is because they are all mounted on the plastic HVAC unit and the sound and motion carries throughout.

2subway

For defrost: YES, big blast of air during sync mode

As for the sound: I noticed when I flashed a flashlight through the defrost vents I could see the plastic vents working (opening and closing)...but when they closed that is when the one on the left side would start to "snap" or "pop" for little bit as the sync test continues.

Footwell: During the sync test: I could feel a sudden blast of air at times but while the sync test ran I never fully noticed a period when the footwell was fully closed. (In other words, there was always air coming through)

While on manual mode and using the vent selector when I selected for only the top vents to be open (defrost vents) all the air was coming through the footwells full blast.

What do you think?
Henry

mleskovar

There are two noises the stepper motors make that I am aware of. One is a ticking noise as the motor shaft slips inside a cracked linkage and the other is a 'snap' (like in your video) when the motor internal clutch slips.


The footwell vents should close completely at some time.

I'm no expert but I've had mine apart 4 (?) times and experienced both linkage and motor failures at different times. It sounds like your defrost motor is slipping the internal clutch in closed position. It's working and if you can get past the noise just leave it alone unless you're willing to pop the top dash. The footwell vents sound like the linkage is broken. Much easier to replace. You can't really tell until you get it apart and look at it. You can run the sync test while apart and watch each location cycle and even pull the connector at each motor to bypass it.

2subway

I've done quite a few DIY on my car and I feel comfortable taking apart as much as possible to hopefully fix the problem. I'm living in Germany at the moment and it's getting pretty cold now days so I definitely need defrost.
What I don't understand is why the defrost vents are opening during the sync test but NOT opening when I select defrost or when using the manual knob to aim the vent selection to the defrost vents.(?)
I could totally deal with the noise if the defrost worked ...at least for now.
Going to the local Mercedes to buy some links tomorrow.
Henry

mleskovar

I was stationed for two years in Boblingen, Germany back in the late 60's. I know what you mean.

I don't understand that either. Are you viewing the flaps during your test just like you view them during the synch test or just feeling for air? From the video you sent I see the wand jumping during a test. Are the flaps opening and staying open once from the beginning of the test cycle then closing at the end or is the giration of the wand on the video the flaps opening and closing during the test? If that's so it probably means the linkage is broken. The flaps should open and stay open until closed for the next flap test. I think it's about 10 seconds? Here's a link for replacing the top dash...not detailed but should be easy to follow. The IC is easy to remove...takes less than a minute with the tool that's easy to make from a coat hanger. See post #13

http://www.********.org/viewtopic.php?f=46&t=69

I still think your footwell linkage or motor is broken.

2subway

I was near Boblingen recently when I was driving to the Black Forest.

As for the defrost flaps.....YES....I kept my eye on them during the sync test. I could see the vents opening and closing for approx 10 sec each time their turn came up. When they would fully close is when you begin to hear the snap sound and I'm starting to believe that the noise is coming from the flap itself snapping (as if the motor is continuing to try and close the flap but the flap is already closed and therefore putting pressure on the flap making it snap). It could still possibly be the internal clutch that you mentioned earlier though.
The link for the top dash didn't appear properly on your post.

Henry

mleskovar

It's being blocked by this forum Here's the quote..."You will need to remove the A pillar trim, left, right and center lower dash panels, IC, then trim pieces around defrost vents to reach screws (2?) and the rest of the dash screws are along the front. After that the upper dash should come out, might need to remove passenger airbag first. You might need a special bit ratchet to remove the stepper motor once everything is removed."

2subway

Mleskovar, I took the C230 to the local Mercedes and had them give me a quote to fix several issues that I've been leaving for later.
They hooked the car up to the computer and told me that all the motors are fine but that the gear on the defrost flap motor is broken and the footwell linkage is broken. It's going to be expensive to fix but I'm getting several things done.
If it was still warm outside I may have tackled DIY on the defroster problem but it's super cold and I'm running out of time before I start driving to the alps for some skiing!
So this is what I'm having done:
1. Defrost gear and Footwell linkages will be replaced
2. Seatbelt in the back seat will not retract (Started acting up 1 year ago)
3. Turn signal arm doesn't stay when placed into left turn signal (broke 2-3 years ago)
4. Winter tires mounted on new rims
5. I like my car so much I'm even getting the sliding cover that hides the cup holder on the center console. (broken into several pieces 2-3 years ago-sun dmg maybe)
6. Polishing the headlights because they're turning a yellowish color

So you can see I've had several minor/cosmetic problems that have just added up and finally decided to get it all taken care of at once.
The most recent DIY I did on this car was to replace the thermostat, O2 sensors, and also took care of the leaking oil problem with the cam sensors and wiring harness.

I appreciate all the help the last few days diagnosing the HVAC.

Henry

mleskovar

As suspected. As long as they have the dash off I hope you have them replace all the gears/linkages. Parts cost is minimal and it's worth the couple of bucks for the the peace of mind to have the updated gears/linkages installed. My experience with the German dealer repairs is very favorable. They pride themselves not only in the workmanship but also give you fair value for your payment. If I were living there I would have them do my repairs instead of doing it myself.

2subway

I will let them know that I want them all replaced to be on the safe side. So far my experience with the Mercedes dealer here in Germany has been good. From what I've seen so far their customer service and shop operates very differently than I've ever seen back in the states.
Henry

harshaiit

I am trying to do a DIY to fix the ticking sound behind my dash....Is it necessary to disconnect the battery before I start....?? Sorry if I have missed reading that anywhere...pls help

mleskovar

No

harshaiit

I was trying to download the PDF at buellwinkle's website (http://www​.buellwink​le.com/W20​3HVAC.pdf)...I get a page not found reply...I tried contacting him for the PDF..by any chance do you have the PDF? I could use that before I do my DIY. Btw I got the parts from KO Performance for $19 and $8 shipping. The delivered it the next day I ordered. Part#: 2038300033. I read someone asking if the part is only available with the dealer. The part I got has the MB OEM logo etc on it...guess its the original one...also they have a $10 part from EZ ( i guess)..i preferred this. In case you have the PDF please send it to me..thanks in advance...

Update: Got a reply from buellwinkle...he deleted the pdf...if anyone has the PDF on HVAC..can you please post it here??

mleskovar

PM me your email address and I'll send it to you....

harshaiit

Hi All....I am stuck at the 3rd screw on the motor which is behind the steel frame and not able to get it out..its a torx 20 and i guess an L shaped tool is needed...any guidance pls?

luca67

I am not sure an L shaped would fit; I remember having to work the screw at an angle, very patiently, trying not not to strip the torx head.
When I reinstalled the motor I swapped the worn out screw with one in better shape and used the bad one for one of the easier to reach motors.
hope it helps,
Happy New Year!

2subway

Mleskovar!
Just wanted to update you....everything that I typed up in my last post (#366) was fixed. As for the HVAC problem, the employee that was in charge of my car told me that they invested a total of 22 hours taking the dash apart, replacing the links, one motor (defrost), and putting it all back together. That portion of the repair cost me roughly 500 euro as they did not charge me for all the extra time it took them to do the repair. I would have to reference my receipts but I believe they only charged me for 6 hours labor.
Just wanted to say thanks for the help when I was looking to DIY and thanks to all others who answered questions along the way.

Henry