Often when my car is on (either accessory mode or engine on, doesn't matter), there is a mechanical "whirring" sound coming from a component in the trunk. The sound cycles on and off every few seconds. It seems to be coming from a black component (pictured) located in the driver's side truck area near the amplifier.

Can anyone tell me what this thing is, and if the sound is normal? Thank you!




PS: The car (2010 550) is somewhat new to me. Only 19K miles, so I'm hoping it's normal, but who knows.

 

Perhaps the pump that inflates the contour seats?

 

Thanks for the reply. Yep, it looks like that's it. After some research, I think I might just have to disable the vacuum pump and go without (didn't use them anyway). It looks like it's going to be a gigantic hassle to repair myself, or an exorbitant expense to have someone do it for me.

In case anyone else comes across this issue, here is some info on fixing/replacing the air bladders and associated vacuum pump: https://mbworld.org/forums/e-class-c...-deflates.html