The ceiling fan has 2 windings. A winding consists of a capacitor that is permanently connected in series. This capacitor is located in the fan housing.
Most of the new ones have 2 capacitors on the switch which they are connected in series with the first capacitor located on the fan. They control fan speed through 3-speed switches.
Connecting the capacitor in series reduces capacitance thus slowing the fan run.
Fault finding signal. If Fab = N moves too slowly at high-speed setting then the capacitor in the fan body is faulty. If the fan runs fine at the high-speed setting but is not running properly at low and medium speeds, the problem is on the switch and there is a 2 capacitor pack on the switch. Switch (supplied to the fan) to pass this switch. If the fan runs fine at high speed then the fan is fine.
Image Source: Google
