A four-way valve (hydraulic valve term) is a control valve with four oil ports. Four-way valve is an indispensable part of refrigeration equipment, its working principle is that when the solenoid valve coil is in a state of power failure, the pilot slide valve moves left driven by the right compression spring, the high pressure gas enters the capillary into the right end of the piston chamber, on the other hand, the gas discharge of the left end of the piston chamber, due to the pressure difference between the two ends of the piston, the piston and the main slide valve move left. The exhaust pipe is connected to the pipe of the outdoor unit, and the other two pipes are connected to form a cooling cycle. When the solenoid valve coil is energized, the pilot slide valve overcomes the tension of the compression spring under the magnetic force generated by the solenoid coil and moves to the right, and the high pressure gas enters the capillary and enters the left piston chamber. On the ot…