I can explain the common functionality of a kitchen fan/light switch.
Kitchen fan/light switches typically have two separate controls for the fan and the light. The reason they only turn in one direction is to simplify the operation and provide a straightforward user experience. Let's break down how these switches work:
Fan Control: The fan control on the switch is designed to operate the kitchen exhaust fan. Usually, the fan has multiple speed settings (low, medium, high, and sometimes an off position). When you turn the fan control in one direction, it cycles through these speed settings in a continuous loop, allowing you to choose the desired fan speed. When you reach the highest setting and continue turning, it loops back to the lowest setting. This design makes it easy to adjust the fan speed without having to flip a separate switch for each speed level.
Light Control: The light control on the switch operates the kitchen's light fixture. Similar to the fan control, it typically has an on position and an off position. When you turn the switch in one direction, it turns the light on, and when you turn it in the opposite direction, it turns the light off.
This simple one-direction control for both the fan and the light makes it easy to use and minimizes the number of components in the switch, which helps keep manufacturing costs down. Additionally, this design has been widely adopted and is familiar to most people, making it intuitive for users to operate without confusion.