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Analysis of the working principle of imported four-way valve and the reasons for poor commutation

The role of the first four-way valve
The four-way reversing valve is referred to as a four-way valve, which is a valve body that is installed in the piping system of the heat pump air conditioner to change the flow direction of the gaseous refrigerant.
The four-way valve can change the functions of the outdoor heat exchanger (condenser) and the indoor heat exchanger (evaporator) to meet the summer and winter heating switching requirements.
The four-way valve for cooling and heating switching also reflects the process of defrosting the air conditioner in winter.
During heating in winter, when the sensor detects frost on the outdoor heat exchanger, the four-way valve switches the flow of the refrigerant to raise the temperature of the outdoor heat exchanger to complete the defrosting operation in a short time.

The principle of the second and fourth valve
The four-way reversing valve is composed of a main valve, a pilot valve and an electromagnetic coil. The pilot valve is used to control the main valve, and the action of the four-way valve is switched by the pressure difference of the refrigerant, thereby achieving the purpose of commutation.

Possible reasons for poor commutation of three-way and four-way valves
1 The coil is disconnected or the voltage does not meet the performance requirements of the coil, causing the spool of the pilot valve to not operate;
2 The pilot valve is deformed, causing the spool to not move;
3 The pilot valve capillary is deformed, the flow is insufficient, and the pressure difference required for the commutation cannot be formed and cannot be operated;
4 The main valve body is deformed, and the piston portion is stuck and cannot be operated;
5 The debris in the system enters the four-way valve to lock the piston or the main spool valve and cannot move;
6 When the pipe is brazed, the temperature of the main valve body exceeds 120 °C, and the internal parts are thermally deformed and cannot be operated. (This is especially important, sometimes not paying attention to the welding, the four-way valve body is not wrapped with a wet rag, resulting in four-way valve failure);
7 The air conditioning system leaks outside the refrigerant, the refrigerant circulation is insufficient, and the pressure difference required for the commutation cannot be established and cannot be operated;
8 The refrigerant circulation of the compressor cannot meet the necessary flow rate of the four-way valve reversing;
9 When the inverter frequency is low, the necessary flow required for commutation is not guaranteed;
10 The scroll compressor causes the hydraulic shock of the system to cause the piston of the four-way valve to break and not operate.

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