Need some help here. Vehicle is 2002 Chrysler Voyager 3.3l v6 with 130k miles. I've got an intermittent noise coming from the front accessory drive. It's not a squealing belt noise more of a "wah wah wah". And it's not consistent. A/C on doesn't trigger it. It seems to start at random.
Last weekend, I pulled the plastic cover off and ran it, but I couldn't get it to make the noise. I pulled the belt and rotated all the pullies and they all felt okay to me. Nothing rough or wobbly. The water pump had some drag on it, which I think is normal.

One possibility is the alternator- supposedly it has a clutch that can go bad. Maybe it's making noise when electrical load is high? Not sure how to diagnose this.

What else should I look at and how do I diagnose it?

-Dave