5 Refrigeration Solenoid Valve Failures and the Solutions

Figure 1: Solenoid valves of various models.

Refrigeration solenoid valve is an industrial equipment controlled by solenoid. It adjusts mass direction, flow, speed and other parameters in industrial control systems. During use, the refrigeration solenoid valve will also fail due to improper use, aging parts, and inappropriate working environment. The following describes five common faults, their causes and solutions.

1. Solenoid Valve does not Work when Energized.

Poor power wiring: reconnect the wires and connectors;
The power supply voltage is not within the working range: adjust to the normal range;
Coil desoldered: re-solder the coil, or replace the coil;
The working pressure difference is not suitable: adjust the pressure difference, or replace with a commensurate solenoid valve;
Fluid temperature is too high: replace the solenoid valve;
Impurities jam the main spool and moving iron core of the solenoid valve: clean it;
Fluid is too viscous or has reached its lifespan: replace the product.

2. Solenoid Valve does not Close.

The seal cap of the main spool or the iron moving core is damaged: replace the seal cap;
Fluid temperature and viscosity are too high: replace the solenoid valve;
Impurities enter the solenoid spool or moving iron core: clean them;
The spring has reached its lifespan or is deformed: replace it;
Blockage of orifice and balance hole: clean in time;
The working frequency is too high or the service life has expired: replace the product or update the product.

Figure 2: Components of refrigeration solenoid valves in sectional view.

3. The Spool Cannot be Pulled in or does not Move.

When the solenoid valve coil is open, short-circuited or burnt out, the spool cannot be pulled in, and the slider cannot move. The coil should be replaced.
The armature of the solenoid valve is stuck, both the spool and the slider cannot move. Open the valve body for cleaning and adjustment.
When the power supply voltage is lower than the rated value of the solenoid valve, the pressure difference between the inlet and outlet of the solenoid valve does not allow the valve to open, causing the spool to fail to close, and accompanied by "ta-ta" noise in the valve. The power supply should be improved.
The flow direction of the solenoid valve is reversed, causing the spool to not move. Adjust the flow direction.
The remanence attracts the spool or the spool is stuck, and the solenoid valve cannot be closed after the power is cut off. Clean and adjust it; if not resolved, replace it.

4. Deformation of Solenoid Valve Slider

If the slider is deformed, even if the solenoid valve coil is energized, the spool of the pilot valve will not move, resulting in the slider not reversing in place. This causes gas to flow inside the valve body, and the high-pressure gas in the compressor forms a short cycle. Then, short cycles cause high temperature, high pressure, along with frequent thermal protection, which eventually burns out the compressor insulation. The solution is to replace the slider.

5. The Reversing Valve is not Reversing

If the pressure difference of the refrigeration system is too large to make the reversing valve to reverse, check the pressure of the refrigeration system or look for the leak point and fill it with refrigerant.

Figure 3: Components of refrigeration solenoid valves and flow direction of refrigerant.

If the slider of the four-way valve does not move or does not move in place, use the wooden handle end of a screwdriver to gently tap the valve body during inspection. Turn on and off the AC 220V power supply from time to time repetitively. If you hear the sound of the armature pulling in and the gas reversing in the valve body, it can be said that the reversing valve has basically returned to normal operation.

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