How does a solenoid valve function?

A solenoid valve functions by utilizing an electromagnet to control the movement of a plunger within the valve assembly. When an electrical current passes through the coil of the solenoid, it generates a magnetic field that either pulls or pushes the plunger. This action opens or closes the valve, allowing or restricting the flow of refrigerant or other fluids through the valve.

Choosing the option that states the valve opens a plunger to allow refrigerant in accurately captures this essential function. This opening permits fluid to flow into the designated pathway, which is fundamental in various applications, such as refrigeration systems, where controlled fluid flow is critical for efficient operation.

In the context of the other options, while they touch on aspects related to valve operation, they do not correctly define the primary action through which a solenoid valve operates. Closing off refrigerant flow implies the opposite action of what occurs when the solenoid is energized, and regulating flow based on temperature speaks to a different type of control mechanism not specific to solenoid operation. Operating through mechanical pressure could relate to other types of valves but does not describe the electromagnetic principle central to how a solenoid valve functions.