So I was having a charging problem (well, 18.5 volts and a boiling battery might not be a problem to some people) and I replaced the alternator with a rebuilt Bosch one out of a yard. (I think it's a 100amp, BTW). Voltage seems fine now and have been driving around for a couple of days with no probs.

So I'm seeing something that was only slightly evident before, but now in a big way. I was driving along at highway speed with the AC on Full and the blower on #4. I had to slow for a stop so I slipped it out of gear and as the engine neared idle, the blower suddenly started blowing much harder. When I revved up again, the blower died down. I played around a bit and realized the following odd relationships:

Below ~2500 RPM:
* Shift up indicator light glows bright (it's been staying on for a while now, never paid attention to it anyway).
* Subwoofer dies (sub amp tied into radio energy lead)
* Blower operates normally

Above ~2500 RPM:
* Shift indicator light dims drastically
* Subwoofer kicks out da mad phat bass (or something like that)
* Blower operates about about 50% capacity

It's very odd to be driving in city traffic and have the stereo and AC alternate between what's dominating the cabin noise.

I'm thinking bad ground somewhere in the engine compartment. Thoughts? Where should I look? TIA.