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Engineers with extensive experience in the field of industrial refrigeration are aware that solenoid valves are widely used in refrigeration units, in roles such as control valves, regulating valves, and safety valves. Although there are many different types of these valves, their functions are essentially the same: they are used to control the direction, flow rate, speed, and other parameters of the fluid within the refrigeration unit. The desired control is achieved by combining them with various circuits. A solenoid valve consists of components such as the valve body, valve core, sealing elements, and electromagnetic coil; any problem with one of these components can result in the valve losing its functionality. After understanding the working principle and components of solenoid valves, let’s take a look at a maintenance case involving one such valve. In this case, a York refrigeration unit in a factory in Wuxi experienced a decrease in its cooling efficiency; the issue manifested as a reduction in power output, which affected the factory’s production processes. When the maintenance team arrived at the site, they found that the solenoid valve was not functioning, which was causing a reduction in the unit’s cooling efficiency. The cause of the solenoid valve malfunction was identified as a short circuit in its coil; ultimately, replacing the coil with the 950A0293H01 model resolved the issue. Here, it is explained that the structure of the solenoid valve coil consists of a pilot valve and a main valve; when current flows through the coil, electromagnetic force opens the main valve port, and when the power is cut off, the magnetic field disappears and the solenoid valve closes. https://p6.toutiaoimg.com/origin/pgc-image/f078212c247c455b84e6c899deea6273?from=pc The malfunction of solenoid valves is a typical issue in refrigeration units. Many engineers and operators used to assume that the reduced cooling efficiency was caused by the unit’s long service life; this is a misconception. It is necessary to diagnose the problem based on the specific symptoms exhibited by each unit. Below, Gonglenghui will explain the four most common faults of solenoid valves and their solutions. I. Short circuit in the solenoid coil: A short circuit in the solenoid coil can occur during heat exchange by the unit, causing an excessive current that damages the coil. The method to detect this fault is to use a multimeter to check for an open circuit; if there is an open circuit, it means the solenoid coil is damaged, and the solution is to replace the solenoid coil. II. Solenoid valve does not function when powered On. The solenoid valve may not work when powered on due to loose or disconnected wiring; to diagnose this issue, it is necessary to disassemble it and check. The solution is to rewire and tighten any loose wire ends. III. The solenoid valve cannot be closed. Generally, the gap between the valve sleeve and the valve core of a solenoid valve is very small; when there are foreign objects inside the valve or insufficient lubricating oil, it may prevent the solenoid valve from closing. To detect this fault, the solenoid valve is removed, and the valve sleeve and spool are taken out to check for any foreign objects. The solution is to clean it with carbon tetrachloride; after cleaning, place the valve core inside the valve sleeve so that it can function efficiently there. Any blockages in the throttle holes or balance holes also need to be cleaned promptly. If the valve sleeve, valve core, or springs of the solenoid valve are damaged, new replacement parts must be used. IV. Problems with the solenoid valve slider: These problems are manifested by the valve core failing to move when power is applied, which results in the valve block not moving into position. The possible causes of the fault are as follows: 1. The solenoid coil is short-circuited or damaged; the solution is to replace the coil. 2. The solenoid valve is stuck and the spool does not move; the solution is to clean the spool. 3. The power supply voltage is below the rated value of the solenoid valve; the solution is to improve the power supply. 4. Foreign objects have entered the solenoid valve; the solution is to clean the interior of the solenoid valve. 5. A loose seal gasket or screw on the solenoid valve can cause refrigerant leakage; the solution is to replace the seal gasket or tighten the screw.