What's that noise when ignition is on? by RoberB

When I turn the key to ignition position 2 on my V6 petrol I have noticed a prolonged humming sound from the passenger side fusebox area.
It is like a servo is working.
It lasts for about 4 seconds.
I have noticed that the note of the sound does waver a bit.
Does anyone know what could be making this sound?

Posted 22 Sep 2011, 09:51 #1 

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(Site Admin)
This is normal, the vent flaps for the heating system re-setting position I believe. The reverse occurs when you switch off.

Posted 22 Sep 2011, 10:59 #2 

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It is a vent flap, but a specific one.

I beliveve its the fresh air / recurculation flap. It's normally open when driving, but closes when the ignition is off. It keeps damp air out, and prevents any draughts through the system when the car is stationary. It's more noticeable on switch off as everything else is quiet. If that's correct then the noise should be repeated if 'recirc' is selected with ignition on.

Posted 22 Sep 2011, 12:06 #3 

These cars are pretty sophisticated aren't they?

Posted 22 Sep 2011, 16:21 #4 

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Yep, flap behind the pollen filter. Was curious myself .

Posted 30 Sep 2011, 18:21 #5 

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In mine it's my wallet going oh no not again!

Posted 30 Sep 2011, 21:11 #6