2001 Chevy Tahoe Squeal on acceleration with A/C on 2001 Ta

Either the tension of the belt is less than adequate, or more than likely you have a compressor that is failing and trying to seize. Does it also do it when you just rev the engine, with the A/C on?

Is the squeal coming from the engine compartment? I don't know what difference load would have on an accessory drive noise, that just engine speed would not. Unless something like crankshaft thrust for example, is causing a slight misalignment in the belt drive system. I searched for service bulletins within GM service info and found none. Obviously, removing the A/C belt for process of elimination would be the same as having the A/C off, sort of inconclusive. If it happens within a short period of acceleration, you could remove the main drive belt to see if you get the noise. You will have no charging, or power steering, and I believe you have a hydro-boost system and would have no brake assist. At this point you could try replacing the belt(AC), and see if the noise persists.