124 Blower Fan Squeaking

[Chazchuzzlewitt]

title says the extent of my problem really- starts sqeaking after an hour or so, like there actually is a mouse going 'round the wheel. Drives me up the wall.
I presume this is the bearings or dirt trapped somewhere?

 

[anyweb]

could be related to this post

http://forums.mercedesclub.org.uk/showthread.php?t=15015