Dash Buzzing for 15 minutes?

#1
Just bought a new '97 BMW M3.

I notice a buzzing from behind the radio;A/C;computer that lasts for about 15 minutes following turning the car off, and then it goes away. It sounds almost like a small fan or maybe transformer and I can't fully pinpoint quite where it's coming from in there. I find it strange that it lasts for exactly 15 minutes and then goes away after the car is turned off. It seems to happen in accessory mode as well.

Is this any known problem or should I start disassembling?

-M
 
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#2
Congrats on the purchase.

I have a 95 and mine seems to make the same noise. I have never timed it though......

Try posting your question on m3forum.net
 
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#3
This is normal. In the brilliant minds of BMW engineers, they have a small fan that pulls cabin air over the temperature sensor for the climate control system. They continue to run the fan after the car shuts off.

Something about keeping the sensor at cabin temperature so that if you return to the car after a short stop, the climate control system will blow proper temperature air, instead of hot or cold.
 
#4
Kirby said:
This is normal. In the brilliant minds of BMW engineers, they have a small fan that pulls cabin air over the temperature sensor for the climate control system. They continue to run the fan after the car shuts off.

Perfect- Just the answer I was looking for. I figured it was either:
- a dying electronic component that still has capacitor charge for a while
- a fan for the radio and\or electronics to cool it

Since it`s neither, then I`m not worried. Thanks so much.
-M
 


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