The VIP version of the technical information contains the following types, "private message" reply to the word "information", for details
| 128G multi-line, modular machine, screw centrifuge data; |
| 52G refrigeration and refrigeration, cold storage freezer technical data; |
| 283G Household Air Conditioner and Motherboard Maintenance Data; |
| 500 set cold storage + air conditioning + fluorine machine + water machine video collection; |
| 200 multi-online/module + centrifugal screw paper books of various brands; |
A four-way valve is a key component used in refrigeration and air conditioning systems to switch the direction of refrigerant flow to achieve a heat exchanger function transition, i.e., a refrigeration and heating mode change. It is usually composed of components such as a solenoid valve, valve body, slider (or piston), capillary, and spring, and has four ports, hence the name "four-way valve"
The four-way valve is a solenoid control valve with four interfaces (hence the name "four-way"), which changes the flow direction of the refrigerant in the air conditioning system through the movement of the internal valve core or slide, ensuring that the refrigerant can switch the cycle path between the compressor, condenser, evaporator and related auxiliary components as needed to meet the cooling or heating needs of the air conditioning system.
First, the working principle of the four-way valve
Power-off state (refrigeration mode): When the solenoid coil is not energized, the spool remains in a specific position under the action of a spring or other return device. After the refrigerant is output from the compressor, it first flows into the condenser of the outdoor unit for heat dissipation, then throttles and lowers the pressure through the expansion valve (or electronic expansion valve), enters the evaporator of the indoor unit to absorb the heat in the indoor unit, and finally returns to the compressor to complete the refrigeration cycle.
Energized state (heating mode): When the air conditioner needs to switch to heating mode, the control system energizes the solenoid coil of the four-way valve to generate a magnetic field. The magnetic field acts on the spool, causing it to change position despite the spring force. At this time, the refrigerant flows directly to the indoor unit (acting as a condenser at this time) after coming out of the compressor, releasing heat to heat the indoor environment, and then switching to the outdoor unit through the four-way valve (acting as an evaporator at this time), where it absorbs the heat of the external environment and returns to the compressor to form a heating cycle.
Second, the air conditioner four-way valve string gas failure performance
The four-way valve is not fully in place during the reversing process, resulting in the refrigerant flowing directly from the high-pressure side to the low-pressure side when the main spool valve is in the middle position, forming a short circuit of the refrigerant circulation. This phenomenon will have a series of adverse effects on the normal operation of the air conditioning system, which is mainly manifested in the following aspects:
The refrigeration/heating effect is significantly reduced: because the refrigerant cannot effectively carry out the complete evaporation and condensation process in the system due to the string of gas, the heat exchange efficiency of the air conditioner is reduced, and the indoor temperature regulation ability is greatly weakened in both cooling and heating modes, and the user feels that the air conditioner is not running well.
Increase of return pressure and decrease of exhaust pressure: The cross-air series causes part of the refrigerant on the high-pressure side to return directly to the low-pressure side without condensation, resulting in an abnormal increase in the return pressure (i.e., suction pressure), and at the same time, due to the decrease in the effective refrigerant circulation, the exhaust pressure decreases accordingly. These pressure changes can be observed from the pressure gauge readings of the air conditioning system.
Abnormal compressor operation:
- Overheating of the return pipe: A large amount of high-pressure refrigerant directly enters the return pipe without sufficient condensation due to the gas string, which increases the temperature of the return pipe, and you may obviously feel that the return air is hot.
- Quieter operation and lower current: As the effective refrigerant circulation is reduced and the compressor load is reduced, the operating sound may become lighter than normal, and the current monitoring shows that the current value is lower than normal.
- High compressor surface temperature: Due to abnormal refrigerant circulation, the compressor itself may have poor heat dissipation, and the surface temperature may exceed the normal range.
System protection or fault shutdown: Prolonged gas cross-gas may cause the system to start up with high-pressure protection, and the compressor to automatically shut down due to high-pressure protection or overheating protection. At this point, the high and low pressure differences in the system may approach or disappear.
Mode Transition Failure: The air conditioner may not be able to switch between cooling and heating modes properly, or it may only operate in a single mode. For example, a faulty 4-way valve coil or a stuck valve body can result in a failure to change, with only cooling without heating or only heating without cooling.
Unstable or uncontrolled operation: If the internal control airway of the four-way valve is damaged, the cooling and heating effects may change randomly during operation, and sometimes even no effect at all, and the control will be completely out of order.
3. Troubleshooting steps for defective four-way valves