Noisy fan

I have a 2003 S40 1.8 auto (2004 model) with air con & auto climate control.

When the air con is on, when I switch off the engine there is a
whirring then whining sound that carries on for a number of seconds.
It is clearly something turning and as it slows and stops the whining gets louder.Also if you place your hand on the bodywork eg.
wing or bonnet you can feel vibration as it comes to a stop. It does
seem to be coming from the cooling fan. The dealer says that this is normal and that all s40's of this spec make the same noise.I cannot see that this can be normal or that it shoul happen at all.
Can anyone let me know if this is normal or whatbthe problem might be caused by.

With the bonnet open you should be able to see if the air con fan wobbles on its shaft. Mine started doing this recently and very quickly degenerated to trying to eat its way through the radiator!


Edited to say:

Obviously, you should do this with the engine OFF and the fan not going round!

even if the bearing are going then it still shouldnt vibrate,the only 2 things that will make it do that are either the bearings are dry and the vibration is chattering of the shaft or the fan blades are out of balance,its probably lost its little slide on spring clip which they use for blade balance and is just clipped to the lightest blade.
As said abopve please make sure the ignition is off and the engine has cooled if the fan concerned is the main cooling fan as it can start up when the engie is stopped.