What component cycles on and off to maintain the desired buck temperature?

The buck thermostat is the correct component that cycles on and off to maintain the desired buck temperature. It functions by monitoring the temperature within a specific area and activating or deactivating a heating or cooling mechanism based on whether the temperature is above or below the set point. When the temperature exceeds the desired limit, the thermostat will turn off the heating element or cooling system, and when it falls below the set point, it will activate the system again. This on-and-off cycling ensures that the area stays within the specified temperature range effectively.

In contrast, a thermal fuse is a safety device designed to be a fail-safe mechanism; it disconnects power when the temperature exceeds a certain threshold, but it does not have a cycling function like a thermostat. A temperature gauge measures temperature but does not actively control or adjust it. The fan relay, while playing a role in controlling fans based on temperature instructions, does not directly maintain a desired temperature by cycling on and off; it's dependent on instructions from a control unit or thermostat. Thus, the buck thermostat is the key component that manages temperature regulation through cyclical operation.