What would cause the sound of running water when turning a corner while the air conditioner is running in a '96 VW Golf?

sounds as if your drain hose is blocked. I had a similar problem many years ago when the heater of my Renault 16 got full of rainwater. Every time I turned a corner it sounded like a washing machine as the fan thrashed the water about in the heater inlet duct. I solved it by poking a piece of wire up through the drain hose (you would have to locate it on your particular car, of course). A load of water came gushing out and it never did it again. (A free mend is always good news!) Good luck That is the answer. I had the exact problem on the exact same model--to find the plug, open the hood and look on the back "wall" of the engine compartment--a little to the left--it is down behind the shiny silver insulation--there is a small flap that you can lift--then poke in there to pull the plug out and let it drain out. it is a cinch.