W203 Dash noise

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neiledgar

Member
Joined
Jul 24, 2014
Messages
49
Location
Lockerbie, Scotland
Car
Mercedes C320 Estate 2003
HI there guys, just a little annoying problem my friend has with his car and its driving him insane!! He has a car almost identical to mine, he has a C320 w203, auto saloon. The other day a funny noise started in his car and he came round to me for advice, mmm goodness knows why, but he did!!!
When he starts the car, there is a tapping noise behind the dash, is appears to be around the back of the heater controls or there abouts as you know noise travels, anyway, the noise is identical to someone tapping the top of the dash with their index finger, a solid tapping noise, not a tick, or a ping but a true tapping noise.
I did suggest that the fault could be one of the control mechanisms behind the dash that operates the heater vents, when you change from floor to screen or anything like that, as i am sure they are operated electronically, rather than the old "Cable/wire" systems of old, and maybe it is caught between settings and moving back and forward trying to settle in the right position.
So we began to move the air flow knob from floor to screen etc etc, nothing! then we tried the fan, nothing and then we tried a whole combination of moves and it stopped, it also stops if you turn of the ignition, but it starts once again as soon as you start it up. He is selling the car and wants it to be right, he has a guy who made a very good offer and he does not want to hand over the car with a fault, hes not like that, so have you any idea guys, what could be causing the problem, it is quite loud, very annoying for him, but more worryingly, is there a fault that need urgent attention, as he wont sell the car unless its right, and he has committed to buying a newer Merc, so needs to get this one perfect so he can complete the deal. Please guys anyone else ever had a similar noise? and ideas? Thanks very much for reading my post
 
Sounds like the very common air flap motor gear failure.

Get the car on STAR to read off the fault codes. Depending on which one it is it could be a simple fix, or a dash out job.
 
Search MBClub or Google for "stepper motor". Very common, very time consuming, and so unless he can do the job himself it will be very expensive for what it is.
 

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