What component do pulse width modulating (PWM) solenoid EEVs control for variable refrigerant flow?

Pulse width modulating (PWM) solenoid electronic expansion valves (EEVs) are designed to regulate the flow of refrigerant in a variable refrigerant flow system effectively. The primary role of a solenoid valve in this context is to control the amount of refrigerant that flows through the system by precisely adjusting the opening and closing of the valve based on the pulse-width modulated signals it receives.

The solenoid valve works by continuously varying the opening according to the system's demands, thus maintaining optimal performance and efficiency. This modulation allows for better control over the refrigerant flow, adapting to changing load conditions, which is critical for the system's overall efficiency and performance.

The other components mentioned, while potentially relevant in different contexts, do not fulfill the same function as the solenoid valve. Check valves are used to ensure flow in one direction, sensing bulbs are temperature-sensing devices that provide feedback to the system, and bleed valves are typically used to release pressure or excess fluid rather than control refrigerant flow directly. Therefore, the solenoid valve is the correct answer because it is the component that PWM controls directly to achieve variable refrigerant flow management.