Humming/buzzing noise from dash after turn-off

[SWB]

I just bought my first BMW, a 1996 328i, less than a week ago. I've noticed that when I turn off the car, there's a quiet, low-pitched electric buzzing/humming noise coming from the dash. This lasts for about 15 minutes or so, at which point it finally stops. I don't know whether this is normal or not, but either way, I'd like to know what it is. Any ideas?

Thanks!

 

[VANCE]

mine does it also...i hope it is normal

 

[Wadula]

hm..at first i though yeah that´s normal mine does that too, but than i read 15 minutes. no mine is just for some seconds and it is the electric motors from the climate control system closing the airchannels so nothing can come in i guess.

but 15 minutes? what temps is it outside where you are? already hot or warm again? then it could be the fan you hear

 

[SWB]

... the electric motors from the climate control system closing the airchannels ...

Yeah, I've noticed those sounds also. The noise I'm refering to continues on past that, though.

... what temps is it outside where you are? already hot or warm again? then it could be the fan you hear

It's still in the mid- to low-40's around here. It does sound like it could be a fan running, but I don't feel any air coming from any of the vents. I gather from your reply that, at least in warmer weather, it's normal for a fan to run for several minutes after powering down?

 

[dirsh]

I read the owner's manual and it says that after the car is shut off, the "parked car ventilation system" turns on. It uses the "blower of the heating and air conditioning system to ventilate the car's interior and lower it's temperature". The length of time that it runs can be adjusted using the OBC

 

[bahnstormer]

yeah its normal guys. lol
don't worry bout it. btw,
wtf are u doing inside your car
for 15 after u turn the key off?
eheheh

=]

 

[logantv325iX]

It's a little white plastic fan in the back of your heater/AC controls. I noticed mine when I was changing the heater core. I don't know if it's there to cool off the unit or what, but that's what it is. Pull out the sunglasses tray by the little finger hole in top. Now reach your fingers back behind the heat/AC unit and feel around on the passenger side of it (I think). When it feels like you stuck your finger in a really fast fan, you found it.

 

[logantv325iX]

Oh yeah, you have to pull the trip computer out, too. It just pushes straight out from the back. If I remember, the fan is about the size of a nickle or dime.