The foot well vents don't close on my 2005 C230 Sport Sedan. (I have copious amounts of hot air in the winter, but the problem is frozen feet in the summer.) I'm assuming the most likely cause is broken levers on the foot well flaps. I understand that it could be the stepper motors too, but the most likely cause and most inexpensive repair is the levers and I am pursuing those first. I have the levers and I am preparing to start disassembly of the dash during the next week to 10 days. I want to set aside a full day in case I run into any issues.

I have two other issues with the HVAC system and I'm wondering I can address them while I have the dash apart:

1. I have the common smelly air conditioning system. I have injected cleaners into the system through the condenser housing as described in the MB Star bulletin. I'm wondering whether there are any other cleaning processes I can employ while the dash is apart.

2. On summer nights after I've run the AC, there are times when it cools down enough to open the windows. When I turn off the AC and do this, the air coming out of the vents seems warmer than it should. Is there another mechanism that could be broken that I need to check?

Thanks

 

thank you for this. first time registering and actually using MB forums. I hope this is still kicking around with people sharing tips and tricks and knowledge such as Racin_fool thanks

 

Not sure if this thread has died, but I wanted to thank everyone who has posted information regarding this issue.

I am at the beginning of my long and arduous process to (possibly) fix my stepper motor/linkage arm. If anyone can advise: my clicking started today whilst driving. It is getting to be winter-time in CLE Ohio and I had to defrost my windows on multiple occasions as I was driving my 05 C240 4M tonight. After turning the defroster on for maybe the 4th time of the drive, the dreaded clicking from the top of the dash began. Once I arrived at my destination, I realized air was not blowing out of the footwell vents from either side (I can hear the air blowing, but the vents must be closed). Tried the HVAC reset and the clicking persisted the whole time as the air was circulating throughout the vents, and air would blow out of the footwells during the reset. Have my footwell stepper motor/linkage arms failed? I only ask because the issue began while defrosting and I did not once turn on the vents for the footwells during the drive. All other vents work, including the defroster vents on the front of the dash. Also, has anyone been successful in replacing a stepper motor by just removing the radio unit? I read somewhere in a thread that it was possible for footwell stepper failures. Thanks in advance.

Do I really need heat on my dang feet? The jury's still out on that.

 

Sounds like the footwell arms have snapped. Not sure why these arms are often the first to go. Change out both arms. While everything is apart you may want to maybe replace a motor or all 6/10 (I think the C240 has 6?). This one is a tough call as the motors aren't cheap. You're basically rolling the dice.

The really dumb thing about these stepper motors is that they generally don't die from an electrical standpoint. The failure is usually a tooth breaking off in the internal gearbox. Open up a motor and you'll see. I've had 2 motors out of 6 fail on me right now (L footwell, and defroster) and this was the case both times. Go German plastics. When a 3rd motor fails on me I'm just going to replace the remaining 4, which will hopefully be the last time I have to take the stupid dash apart. Just FYI, the defroster motor is the most inaccessable, and requires removal of both the glove box and upper dash.

Behind the radio there is the plastic tray the radio slides into. This part has tabs that go behind the trim pieces where the driver and passenger knees are, and those trim pieces cannot be moved or shifted without removing the centre console. Once this thing is out of the way, there is still a piece of foam with plastic backing. I guess you can cut a hole with a knife through this part, but even with everything removed there is still a crossbar or two in the way that severely limits screwdriver access. I imagine it would be difficult if not impossible.

 

Looks like I'll be ripping apart the dang dash/console soon. Love working on my Merc but REALLY not looking forward to this job. Maybe I'll wait till it warms up. Not prepared to replace all of the motors, but if all goes smoothly during the repair I've seen some users move the gear 180 in order to get fresh plastic teeth instead of the worn away teeth and I might see if that works, worth a shot at least. Wish Mercedes would have thought into the future with this inevitable failing plastic design.

 

It sounds like you had the upper dash removed, do you think I could cut the hole and unscrew and removed the motor from the engine bay without touching the dash? Thanks!

 

My daughter has a 2004 C240 4Matic and it has the dreaded clicking noise coming from the foot well servo motor for the climate control. I’m a chiropractor living in Canada and out of work temporarily because of the corona virus so I thought I would take this project on with the understanding that it could take me 3 to 5 days to complete. Just a few misconceptions, you do not have to modify the new motor in any way and you do not have to force anything in this whole project with the exception of pulling the cage out that holds the radio and climate control apparatus. You will need to be familiar with the different connectors that are used to connect the electronics to the parts as there are three or four different kinds, again, you need no force any of them off. For the most part I followed YouTube video and it was excellent. However he did suggest that you cut off the spindle buy an eighth of an inch or so on the motor in order to make it fit. I will repeat… you do not need to modify or force this stepper motor

.

The only problem I ran into in the initial stages was an oversight on my part where I did not know there was a screw above the hood release handle holding the headlamp switch assembly…lost 45 minutes . The other part that I struggled with was getting the cage out that holds the radio and climate control, it’s a black cage. Please note that there are two plastic tabs at the top of it that push through and allow it to hook on to the brace. Under the instruction of one of the blogs they used a large flat screwdriver to push through the holes in the brace and straighten out the tabs that secure the cage the brace.

I did not have any difficulty getting motor 2/15 (footwell flaps) out of the climate control unit. And because of that I realize that it should go in without any modification or force. However, I did spend the better part of two or three hours trying to get the motor and its arm or linkage back in. At the end of the day here’s how I did it;

I’m in Canada and this is a left-hand drive vehicle. So using that as a reference I held the motor in my left hand and pushed it up into position with it lying on its side by going on the left, our driver side, of the brace that is positioned in front of the stepper motor. With my right hand I held the linkage or actuator arm and attached it to the splines or spindle on the motor. I then attached the end of the arm to the linkage from the climate control unit. I then moved the motor and its attached arm down into the small recess in the climate control unit that accepts the arm, a small circular recess behind the brace. Once I figure this out it’s about a five minute job. I hooked up to the climate control unit as they have in the videos and ran through the testing of the flaps, everything was quiet and worked great. I had some difficulty getting the cage or the black shelving unit back into its position so I decided to put it in without putting the tabs through the bracing bar, I just used a pair of pliers to squeeze the tabs then force the shelving unit into place and put some screws in. It worked fine.

I had an SRS code that I have triggered that cleared when everything was back together. I hope this helps everyone. I’m embarrassed to tell you this probably took me 10 to 15 hours to do. I was quoted 10 hours of labor to do the job plus Parts and taxes. I think this would’ve been an $1800-$2000 bill at MERCEDES. I chose not to use a second-hand motor. I bought one locally from a supply store for C$130, there’s just too much labor involved to put a used motor in and have it fail shortly after.



Knowing what I know now I think I could do the job in four hours or less. Hope I’m back to work soon...this mechanic-ing is killing my back and neck!

 

My clicking sound are more intense than anything I've seen on the internet, can anyone tell me which motors are broken?

Here's the video of my dash:
Window, footwell and far left/right corner vents work fine, but the driver/passenger and center vents don't work at all.

 

Dumb question, but are you sure that's not from a speaker? Need to ask this as I thought some of the earlier W203s had a speaker there, possibly as an option.

If that's not from the speakers, then it's most likely a broken gear tooth. You're looking at replacing at least one of the motors. However I am unaware of any motors in that area. Are you sure it's not slightly off (0.3m or so) to one side?

There are several reducing gears inside the stepper motors. Based on the speed of the ticks, in your case the broken gear would be one of the "middle" ones instead of the large "final" one that most of us are having problems with.

 

No, I don't think it's a speaker, because it has a vent open/close circle thingy.

It might be slightly towards the left (driver) side. Are there any "easier" ways to replace that one?

Also, are all of the stepper motors the same? I mean, do they have the same code etc.?

 

There is no easier way to get to these things. There's a reason this thread got stickied.

All stepper motors are the same.

 

Sorry if this has been asked already, but I found out that my all of my vents actually work, however the ones I thought that didn't work (driver/passenger and center) only blow cold air. Is it because of the motor as well?

 

Yes it is. The blend motor has failed. This one controls the dampers that control the mixture between hot and cold air.

 

So I have to replace multiple motors or could it be the same one?

I should rephrase that, is a blend motor the same as the stepper motor?

 

They are all (identical) stepper motors with the same PN. They each serve a different function depending on where they're installed. So you have a broken stepper motor that controls the L blend, or the linkage to that motor is broken. That is the minimum problem. There may be other broken motors or linkages as well, though it would be obvious (for example there is no air to your feet or defroster etc.).

See post #56 to see where each motor is located.

As nobody else can see your car, you'll have to open up the dash and see what else is broken. There's a good chance there are several problems that have either happened or are imminent, especially if you never had the linkage recall done. At minimum you want to update all the linkages. The most expensive but permanent(?) solution is to replace every motor so you don't have to open up the dash a 2nd time. This repair is painful.

 

My center vents and passenger and driver side almost don't work.
Cold air is very low and I got no hot air.
No clicking noises, so maybe a stepper motor is dead?
Could someone guide me in the right direction? What is the one I have to check?

 

^ See link in post above. Everyone has to deal with the same problem by opening up the car. Obviously I would check the dampers to the footwell as well as the blend air motors and linkages.

 

Thank you for your response.
I saw the post that you are talking about, but it don't know what is the one that is not working.
Footwell is working OK, it blows hot air, my problem is the center vents and sides. Only blow cold air, and almost no pressure. The center vents blows a little more to driver side.
What stepper number would it be?

 

^ Yes it does. See post #56. Sounds like your blend air motors M2/5 and M2/7 are malfunctioning. If no air is blowing, that is caused by either a damaged gear in the motor, or a broken linkage that the motor connects to. Again, you have to open the dash and check the corresponding linkages and motors to find the culprit.

The footwell motors and linkages (particularly L side for LHD vehicles) are most known for failing for some reason. There is an upgraded (reinforced) set of linkage arms available from the dealer. Personally I had both the linkage and motor gears fail.

 

There is some air, but only cold. Windshield, window and footwell work ok.
So M2/5 and M2/7 are behind the glovebox? How do I get there? I searched for some instructions, but found nothing on those.

 

Sounds like the motors that control the hot/cold mix for each side are broken, or you'd be getting warm air. The fact that you're only getting some air but not full airflow tells me that you probably have a broken linkage(s) as well. If I were to guess, you're looking at 1-2 new motors, and the linkage kit I mentioned earlier. Because of the work involved, I would highly recommend updating the footwell linkages (the original ones are known to be too weak for the job and have a very high failure rate) while you have everything apart.

Most of the motors are actually behind the radio. However, removing the radio is not good enough. The surrounding trim has to come out as well. To be specific, 4 motors are behind the radio, 1 is behind the instrument cluster (on a LHD car), and 1 is behind the glove box. This is assuming you have the basic HVAC system (6 motors). The deluxe version (digital display, only for C320 and higher trims I believe) has 10 motors.

See post #18. Someone saved the full instructions as a 3 part PDF file.

 

I've already read that pdf, but it does not include the motors that interest me. M2/6 and M2/7 are not behind the radio. That's why I was asking how to get to them.

 

^ Yes they are. They are slightly higher up and on the sides of the airbox (facing the L and R sides of the car). Post #56 has a diagram. The procedure to reach them is the same. However, after everything is removed there, you may also have to remove the glove box followed by the upper dash. At that point all 6 motors will be easily accessible. Ask me how I know.

 

Oh, I see them now, thank you so much.
I guess I have to find the time to do it then.

 

Youtube is your friend. Check out this video:
I owned my C320 for 19 years. I had stepper motor 3 times. If the motor dies, you'll experience problem getting to the right setting. If the linkage dies, on top of that, you may hear the annoying constant flapping noise. The motor was like $2/300 dollars, and the linkage is 1/10 of that. The problem here is more about the labour cost than the parts. Like mentioned above, there are 10 stepper motors in my car. The first time I had the problem, the car was still relatively new. I had it fixed at the dealer. You basically need to take apart the dash and the radio, at the minimum. You'll reach some stepper motors. There are some hiding behind the steering column. So how much time it takes depends on how much you need to dissemble to reach the stepper motor. The dealer told me the best case scenario is 6-8 hours of labour. Worst case can be 12 hours.

Second time, I didn't have it fix at the dealer to save some labour cost. Third time, I did it myself and that culprit was the one behind the steering column. It's a one week job for me.

In the third time, I managed to get a set of 3 old stepper motors and some linkages from the dealer, just in case. The stepper motor(s) controlling the footwell is probably bad now. There's always a bit of air blowing to the driver side footwell, but no air going to the passenger side footwell. There's no snapping noise and I don't mind my passenger getting cold feet, so I am okay living with it

Despite have these problem and some normal wear and tear that I need to fix, this is a great car. It is still rock solid after almost 20 years. Recent MB build has really gone downhill. My brother's first MB was older than mine, and it still runs. He had to get rid of his 2nd and 3rd because there were so much problems. He finally gave up on MB.