OK so this has happened before, but the last time was at least 8 years ago
or so and I forget what the mechanics did at the time, but now I'd like to
try my hand at fixing it...

Lots of vibration from the front fan assembly when the fan kicks on... my
wife was driving the van home today and she described it like going over a
rumble strip only there was no rumble strip.  She pulled over and turned the
van off and the sound kept on going (she had the AC on at the time).  After
the van cooled down a bit she started it up and no sound.  I'm unsure if the
sound will start up again if the engine heats up and the front fan kicks on
or if it only occurs when the AC is on, I'll check that out tomorrow.  Might
it be the thermoswitch for the fan or is it the fan motor itself? There are
a number of speeds for the fan, no?  One for the engine temperature and one
for when the AC is on??

Any help is appreciated.

--
Dan Erlandson
Flemington, NJ
> danoer1@eclipse.net
91 VW Vanagon GL 174,000 mi
99 VW Passat 111,000 mi