Elmonte

Hi, during a cold winter day I started my car and heard this loud clicking coming from behind the dashboard. I went away after a while and now every time I start the car, I hear the clicking noise for about 20 seconds and then it goes away. I don't get heat or ac to the feet. After doing a lot of research and reading in the forums, I found out that it is most likely the foot well stepper motor linkage. I got the little plastic parts from the dealer and read the DIY Noisy Air Conditioner ?? Stepper Motor Replacement / Clicking & Hissing.

I found and uploaded this diagram that shows all the flap motors.

I followed the DIY and found out that the [M2/10, M2/15] motor had the linkage replaced already and seemed OK.

The clicking noise has gotten quitter with time. The sound is close to the back of the dashboard. I'm suspecting the [M2/8, M2/16] motor to be the problem now.

Any help would be appreciated before I dig in to this again today.

Glyn M Ruck

Likely M2/6 or M2/8, M2/16. You are going to have to trace by where the noise is coming from. Lucky you don't have a C320 with 10 of the darn things.

Laloggia

Worst design ever...mine has made the noise since I bought the car. Can't fathom pulling the dash apart to fix. I have heat and a/c...thats all that matters. Once that stops, its fixin time.
Good luck with your repair...Carsoft/star should diagnose which stepper motor is not working properly.

Elmonte

So it turns out the [M2/10, M2/15] stepper motor was bad. I swapped the [M2/19, M2/21] stepper motor with [M2/10, M2/15] and they both worked. For some reason the foot well might have required a stronger motor.

So just to clarify, the linkage was already the new design and it was fine, the foot well stepper motor was bad and I swapped the two motors that were behind the radio and now they both work.

Thank you for all your replies.

vr2whf

How long does it take for you replacing the stepper motor and the linkage? I learn from my friend that the complete dashboard removal is a painstaking job.

I have a C320 and got the diagnostic code when running the SDS computer health check.

Elmonte

It should take about 5 hours in total to replace the ones behind the radio head unit. If I had to do it again, it wouldn't take me more than two hours to do the job.

I definitely recommend doing it yourself as the mechanic would charge you at least 3 hours labor. Good luck

hanknum

I just replaced both bottom arms (both were broken) on my C320, only to have the clicking continue. Sounds like it is coming from the upper drivers side which would require removal of the upper dash too. The lower dash and console was a PITA! If you know it is only the bottom levers, then I'd say it would be questionable not knowing your mechanical ability. If you have to remove the upper dash then I'd say don't do it. I'm going to leave it as is. At least with the bottom ones fixed, I won't be freezing my feet like before.

edgarinho10

Complete dash removal is just time consuming. It would probably take no more than 4 hours from start to finish and less if you have have help or have done this before.

02C230C Lebanon

Now I have the problem with my 2002 C230 K Coupé. I hear the clicking sound and can't have air out of facial (dashboard) vents (everything else is working fine). How can I determine and locate the faulty arm/motor?

Dave T

Yes, I have the dreaded click now too! One added issue is that the radio/Command system won't come on until the clicking stops. This is going to be fixed this week...quite annoying to deal with.

Dave T

Well, not all clicks are faulty stepper motors! Mine turned out to be a problem with the Command system itself. Dealer replaced it with a brand new unit. The extended warranty paid for itself once again. My oil cooler was replaced at 53,000 miles, now this at 66,000. The console between the front seats has had the interior replaced twice during the extended warranty, a windshield washer leak as well.

vr2whf

Why you need to replace the oil cooler?

Dave T

It was leaking oil. First they replaced the connection seals, that didn't do it, so they replaced the whole thing.

CandyS

who can fix the clicking sound mechanic or aircon technician?

lkfoster

At least MB is consistent. The MIL's 560SL has a bad AC vent vacuum actuator that requires removing the dash to get into the heater box.

baha411

Here are two videos showing the stepper motor problem and how to fix it:

quip11

That's a nice video baha411! It gives a nice insight on what to expect. Although it's great to have, some pics don't give a total picture of how its like after everything is opened up.

I have yet to tackle mine. It's so hot lately that I'm waiting for the weather to cool down a bit. My question though, I don't hear clicking or ticking sounds but only a loud hissing sound when I turn the AC on. Hardly no air coming out of the middle vent or the dashboard vent and it can get hot quickly. I will try to find the diagnostic sheet given to me. I was told that I needed stepper motors too based on that print out.

Is it possible to have the same problem without the usual clicking/ticking sounds, only what I described above?

Thanks!

baha411

Thank you quip11 )

I am not sure where the hissing might be coming from, but it is possible that one or more of the stepper motors are dead and vents are not opening.

Not necessarily they will create clicking sound if they are broke bc each motor is designed differently, some have gears and some have arms.

If no air is coming from all the vents of the dash, I would be worrying about it because I don't have any guess what the reason would be, unless all stepper motors are dead and they are locked in closed position, which is unlikely.

I am not sure if you already did but I would make sure that AC compressor is working properly first. If the air is hot, I m not sure if you can directly connect it to stepper motors. You might have other problems, such as faulty compressor, faulty pressure sensor, faulty relays etc...

For my car, initially I had to replace pressure sensor that is under the radiator, because the AC was not working at all (compressor was not blowing any air). Realized that I broke the pressure sensor when I was parking I hit it to concrete block under the front bumper... you probably don't have this problem, I am just saying in case...

It takes a long time to fix this problem but if you have free times and you are patient a bit n you like to play with electronics, it might be fun too.

Also if you need stepper motors I have got a few lemme know if you want them (used ones are pretty cheap).

Hope this helps and good luck...
Baha

quip11

Thanks Baha. I've purchased the arms and linkages already but not the stepper motor yet. According to the MB indy I went to, that performed the diagnosis, my compressor and related parts are ok. I originally came in for a freon recharge since I feel no cold air. As it turns out, he said that my problem lies within the dash. There's some air coming/blowing in, but not strong, even if the switch is on max.

I guess I have to find the paper that was given to me. The stepper location is similar to what's being discussed here in the forum for this topic. I'll post it as soon as I locate it.

I might take you up on that stepper offer, I only need to know how many

Again, I'll give an update as soon as I can.

baha411

You are welcome )
Hope you will figure it out soon.

Baha