Wes,
I've recently BTDT.  My fan just stopped dead, blowing fuses without so much as a whimper.  So, a fan replacement was in order.  I have a '91 Carat, so there may be some differences.  The fan is not really serviceable since it is really very, very well buried in the dash.  So, if you're going in, I'd recommend replacing it.
In a nutshell, you're going to remove most of the dash, remove the "air box", and then you'll be able to remove the motor.  This is a fairly straightforward disassembly-reassembly repair job.  I had to cut two wires (one for the fan power going into the box, the second for a stupid dash light I could not get loose), I just spliced them back together and all is well.  You'll need basic tools for the job, and it's easier to have the help of a friend/spouse/neighbor when you take the dash out.  I'm sorry, I didn't document my job very well.  It's not too difficult and you'll learn a great deal more about how air flows in the van and what all those wires are used for.
NOTE: those switches in your dash, the fan switch, A/C switch, etc., study them a bit for easy removal and note that you CAN remove the connection from the rear of the switch itself.  These switches plug up VERY TIGHT which led me to think that I HAD to remove the switch from the dash.  Guess which switch I broke before I learned this lesson?  That's right, the switch to the fan I just replaced.  Murphy waited until the end to have that fun with me :-)
Original Message:
Okay guys,
the heater,etc. blower fan in the front cabin has been sounding for a
while now like it's been on its last legs.  It squeals sometimes, and is
sometimes just generally very lound.  Twice in two days, its blown the
fuse.  Anybody have experience with this problem?  Can I do something to
fix the fan?  Or will I need to replace it?  And how big a deal might this
be?

Thanks for any help,
wes