I think in the US the expression "oscillate" is now commonly known. The advertisements for these fans refer to them as "oscillating fans," and when you see them in boxes in the stores, "it" usually says "OSCILLATING FAN" in big letters on the box. I'm afraid "rotate" and "turn" might imply that the fan was not working at all. The only clear alternatives I can think of are "wig-wag", or "go /