I'm pretty fair with the electrical stuff but I'm confused on this one.

When I put my charging setup together, I had a virtually new Bosch alternator off a Deere 6 cylinder. Little lower amperage than what I'd like but hey, it was a freebie. 60 amps I think it is.

So when I did the hurry up to get it running to go on the move truck it squealed with the electric fan when I ran the rpms up. Pretty much anything above say, 1500 rpm. Hmm, interesting. I figured it was the way I had it wired in, though I couldn't tell you why. It was hooked to the switched side of the key switch.

I know it's the fan cause if I unplug it, no squeal from the alternator. It's got a serpentine set-up so I don't think its belt tension.

I popped for a new 100 amp GM type single wire alternator and a continuous duty solenoid to run the fan and other accessories/circuits, since I'm doing some re-wiring anyway. Installed it, charges well, but I've still got the squeal.

Any ideas?