1997 E300d 210 Body - Electrical Hum
 

Hello all:

On starting the car, I get a audible background electrical hum which appears to emanate from the glove compartment area. The hum appears to be louder when the car is cold. As the car gets warmer, it appears reduce a little bit but never disappears. Any ideas?

Thanks.

Beneath the glove box is the blower motor for the ac/heater.

Two charcoal activated filters are accessed from below and two cabin filters are accessed by removing the glove box guts.

The latter get very dirty after 30K miles, restricting air flow.

Yeah, I was thinking blower motor too...you ought to be able to confirm it by shutting the system down (tap (-) on the blower control until is says "off").

If the noise stops it is the blower. Maybe new filters will fix it if you are lucky, maybe the blower is on its way out...it's not a hard job to replace it, not like on older M-Bs but the parts are expensive since you'll need to upgrade to the new blower/regulator (about $600) or just find a used one on ebay and pop that in for a few $.

1997 E300d 210 Body - Electrical Hum
 

Thanks. I plan on changing the motor and carbon filters, however, the hum is audible on starting the car and when the fan is off.

If your fan motor is bad perhaps it IS the cause of the noise?

You can take the kick panel off about the pass side footwell easliy enough to see if it becomes louder.

Are you sure the hum isn't the little fan near the lightswitches on the roof? Used for drawing air past a temperature sensor.

How do I access the fan near the light switches on the roof?

You have to cut the roof off with an angle grinder.

No not really, you just remove the light cluster.

Thank you all so very muych. The problem turned out to be the climatic control sampler blower motor located in the interior light cluster. Special thanks to the Parrot of Doom for his tip to access it!

Parrot - thanks for the morning laugh.

How do you take the kick panel off the pass side? I have a handfree kit I don't need and need to get access to that area to remove it. I was able to get the portion off by the center console but was affraid to undo the part above the knees as I didn't want to brake any of the clips. If you know I sure would appreciate you sharing your knowledge.
Thanks,
Mike