Most likely this is the rear fan which blows the cool air from the AC unit to the back of the SUV. If this has always been the case, then there is no problem. If the whirring just started it could be a sign the compressor or another part of the AC is breaking down. Have it looked at if the whirring noise just started and don't wait until it breaks, because it can ruin or damage other parts of the system. Find a reputable mechanic and specialist in AC like Ice Cold Air in the south. The water droplets sound like a compressor problem, but I wasn't sure if these were inside the vehicle or outside? Either way, new noise=go to mechanic. Simple equation.