My Dyson air multiplier technology had F2. I waited for an hour as the previous post mentioned, but F2 was still on. My filter is clean. Here what I did from several trial and error. When I turnedon it showed 10 for few second and changed to F2 again. I unplugged and plugged back, turned on and the moment it showed 10, I pressed power level down to 5 or whatever. This made the fan on.