TRankin

Yesterday, I backed my C300 Sport from the garage into the driveway. I cleaned the wheels then pulled the car back into the garage. A couple of hours later, Idecided to clean the exterior of the windows. When I was cleaning the windshield, I could hear something running...sounded like the Heater/AC fan. The key was not in the ignition and all the doors were closed. It was a very faint sound.

Any ideas? I tried doing a search, but didn't find any information.

lamonsas

i hear that too after i turn the car off lol dunno wat it is

killerg

have u considered ghosts?

rich09

I have the same noise, sounds like a fan.

lamonsas

Lmao

Toast

I noticed the same noise too, sounds like a computer fan to me.

Do you happen to have the COMAND/Navigation package? Maybe its the fan for the brain of the nav to cool everything down?

lamonsas

Nope I got The stock audio 20

tanktube67

I believe is the electric water pump

TRankin

It does sound like a computer fan now that you mention it. However, I don't have the COMMAND/Nav package.

I didn't have my car running long enough for anything to get hot and the air temp was low 60'sF. Plus, when I heard it, the car had been sitting in the garage for around two hours.

C300CA

I also noticed similar sound. However, when I sit inside, close all doors, not playing anything that relates to electrical controls, and wait long enough for like 5 minutes (I didn't count), the running sound is gone, no sound at all. At soon as I open one door, the sound comes back. I haven't tried other things to find what else will bring the sound back.

C300CA

Just for fun, I sat inside and closed all doors. after about 3 minutes the sound was gone. I turned on the vanity mirror lights, no sound. I pushed back dome light button, the sound came back.

jctevere

Are you guys talking about the noise you hear about 30 seconds after you shut off your car, and then again after like 2 minutes of your car being off?

To me it sounds like a valve or something closing in two stages. One 30 seconds after the car has been off, and then again (in a different area further into the engine compartment) a few minutes after the car has been off. I have assumed that these are ducts that close the air vents or something to help insulate the car from the outside?

C300CA

I am talking about the noise not engine related. Any time I open the door, this noise starts. Three minutes after all doors are closed and no electronics are played (vanity mirror light is an exception), noise will disappear. Noise is very low but i can hear it, like a quiet fan or a CD player running.