1998 Voyager Blower noise

I'm wondering if anyone can shed some light on this one since I can't find
any similar problems via google...

My wife started complaining that she was hearing noises whenever she made a
left turn. I took the car out and tried to re-create the problem and
couldn't but I did get a very odd noise when I turned on the heater to
defrost the windshield. All I can describe it as is a kind of
rattling/revving noise that went on for about ten seconds then stopped. I
defrosted the windshield, then switched over to the main vents and cranked
the heat. The heat was working fine.

The last time something like this happened it was the AC compressor that had
died but that was only about five months ago and it was a very different
noise (almost a squealing noise) with the accompanying failure of the AC
system and a metallic smell coming from the vicinity of the compressor. I
turned on the AC and it got VERY cold very fast. I left the van running, got
out and leaned in close to the compressor. No smell. What could cause that
noise?

 

Okay, I was able to get a better listen and here's what it sounded like:

I let the car sit for about an hour then started it up again. Again, the
same noise. It was loud. REALLY loud. I popped the hood and was able to
pinpoint the location to the vicinity of the compressor but it sounded
like it might have been belt noise. The first thought was that the belt
was wet (it's raining pretty hard around here right now) but after it
subsided, again after a very short amount of time, there was no burnt
rubber odor and still no metallic odor that would indicate a blown
compressor. I drove it around a little, changed the setting on the
blower between defrost, heat and AC and everything is still working
fine. It's just that god-awful noise at startup.