Which of the following is NOT a function of a motor controller?

The role of a motor controller is essential in managing how a motor operates, and it encompasses several specific functions. Starting and stopping the motor is a primary function; motor controllers are designed to initiate motor operation and halt it safely when necessary. Protecting against overload is also a vital function, as motor controllers often include protection mechanisms to prevent damage to the motor due to excessive current conditions. Regulating the motor's voltage supply is another critical responsibility, which ensures that the motor operates within designated voltage parameters for optimal performance.

On the other hand, controlling the ambient temperature is not a function of a motor controller. Ambient temperature regulation pertains to environmental control systems rather than motor control systems. Motor controllers focus specifically on the operational characteristics of the motor itself rather than managing surrounding environmental conditions. Therefore, the function of temperature control is not aligned with the primary purpose of motor controllers, making it the correct choice for the question.