Final answer:
In a reversing valve, the internal slide is moved back and forth by the pressure differential created by the refrigerant, with the aid of a solenoid coil when it is energized.
Step-by-step explanation:
The internal slide in a reversing valve, also known as a four-way valve or a reversing heat pump valve, is typically pushed back and forth by pressure differential. This pressure differential is created by the refrigerant circulating through the air conditioning or heat pump system.
During operation, the reversing valve changes position to switch the direction of the refrigerant flow, which consequently changes the function from heating to cooling, or vice-versa. A solenoid coil, which is an electromagnet, is energized to initiate the slide movement by creating a pressure difference within the valve.
Once the solenoid is energized, it shifts the internal mechanisms, allowing the high-pressure refrigerant to move the slide to the opposite position.