Since the motor of the exhaust fan in the bathroom is an AC motor, why can it rotate forward?

Why can't AC motors rotate forward and reverse?

There is a problem with the placement of the coil in Figure 3, and the relationship between the two windings should be 90°!

The principle of a single-phase motor was introduced above, in which the capacitor is responsible for splitting the phase, that is, generating a voltage with a phase difference of 90° from the input voltage, supplying another winding, thus generating an elliptical rotating magnetic field!

To change the direction of rotation, you can change the X and Y contacts in Figure 2. (Swap the 220V input from X to Y).

Take a good look at the information given to you, I hope it will help you!

If the exhaust fan can be reversed, then its front and secondary windings are symmetrical, and by changing the position of the wiring, the steering can be changed, just like the washing machine can be reversed.

The stator winding of a single-phase motor is composed of a main winding and a secondary winding, as long as the line end of one of the windings (both main and secondary) is arbitrarily adjusted, the current and the magnetic field interact, the direction of the rotating magnetic field changes, and the direction of rotation of the rotor changes. When the wire diameter and number of turns of the main and auxiliary windings are the same, the rotation direction can be arbitrarily adjusted to the windings.

The steering of the single-phase motor can also be changed. Just swap the two ends of the starter coil.

Forward and reverse, whether it can be controlled, or whether it occurs randomly every time.