Electric motor noise from dash?
 

Hello there,

I've just started taking Boxy (1982 300SD) out for spins around town, and I noticed when I sit stopped at stoplights that there is a noise coming from the dash. The best way I can describe it is an electric motor or servo noise. It is faint, I can only notice it when climate control is all off, and I don't have a radio right now so no other noise. It sounds like it goes on and off, or perhaps back and forth? I have no idea what it could possibly be. Without the climate control on there shouldn't be any activity back there, and I can't think of any systems that could produce that sort of noise, except maybe the cooling system (the w116 "evil servo" comes to mind). I don't hear it when I open the hood, but then again I've got a nailing injector making a racket:furious2:

Does anyone know what it is? Should I be concerned?

There is a small motor that draws air cabin air across a temperature sensor. The motor is under the glovebox, but I think it turns off if the O button is pressed on your climate control unit.

I get that same sort of thing in my 123, it sounds like it comes from behind the climate control unit.
Nothing will be on, no radio, heat/air, lights etc... it sounds like a buzzing sound. it comes and goes and can be a little louder at times.
when we stop, so does the sound. also it doesn`t do it all the time.

I even swaped the CC units thinking it being the cause somehow. sounds like maybe a relay.

Be interested to get to the answer to this.

Charlie

It sounds like a servo or electric valve opening and closing. My climate control is off, the big O button is depressed. :huh: