In a PWM solenoid EEV, what does the control signal do?

In a PWM (Pulse Width Modulation) solenoid Electronic Expansion Valve (EEV), the control signal is crucial for modulating the flow of refrigerant. The control signal operates by rapidly switching the solenoid on and off, which effectively varies the amount of time the valve is open compared to when it is closed within a given cycle. This on-off switching creates a modulated flow, enabling the valve to adjust to varying thermal loads and conditions in the system.

This allows for precise control over refrigerant flow; as the duty cycle of the PWM signal changes, the valve opens and closes at different rates, optimizing the refrigeration cycle's efficiency. It is this ability to rapidly vary the valve position that makes choice B the correct answer, as it emphasizes the dynamic and responsive nature of PWM control in an EEV system. The other options do not capture this variability and modulation aspect of the control signal, making them less accurate descriptions of the operation of a PWM solenoid EEV.