Common electronic expansion valve problems for air conditioners

Common electronic expansion valve problems for air conditioners 1. Principle of Electronic Expansion Valve    The angular displacement generated by the stepper motor drives the rotation of the valve needle in the valve body, thereby realizing the automatic adjustment of the flow area of the valve port and playing the role of automatically controlling the refrigerant flow of the system. Second, whether the electronic expansion valve is good or bad:   Step one (see): Whether the wiring is plugged in place and whether the circuit is damaged. Step two (listen): After the power is turned on, there is normally a "click" to check whether the coil is in place; Step three (measure): measure the coil resistance, insulation resistance and the voltage of the main board when the power is turned on. The winding between the common terminal COM (usually gray/blue wire) and other wires is generally more than 40 ohms. The coil supply voltage is usually 12V square wave pulse. Step 4 (Valve Body): If there is no abnormality in the above inspection, and the valve body is frosted or clogged, tap the valve body to see if it can be recovered. If it cannot be recovered, replace the valve body.    Third, the reproduction of electronic expansion valve cases:    Phenomenon: The customer responds that the indoor unit of the air conditioner is working normally, but it does not cool. Occasionally, the master checks the indoor and outdoor units of the air conditioner and hears the sound of "click, click" to determine the possible problem of the electronic expansion valve. Check: According to the air conditioner pressure from high pressure to negative pressure, the system may be blocked somewhere, and the sound of "click, click" of the electronic expansion valve may not be heard when starting up. Then the flow rate of the capillary is controlled by the electronic valve, and the machine can sometimes work normally To determine the electronic expansion valve. Treatment: The master of the outlet visited the machine and found that the fans of the internal and external machines were turned. The operating current of the external machine was measured at 4A. The compressor was normal. The low-pressure compressive stress was measured at 1Kg, and it also decreased. The current slowly increased. Turn on the air conditioner power supply, the pressure gradually decreases from negative pressure to about 17Kg, the system is initially judged to be blocked, the resistance valve coil is measured, the voltage and resistance are normal, and the sound of the electronic expansion valve opening cannot be heard when the power is turned on. Remove the electronic valve coil and use Lightly tap the screwdriver handle, the pressure rises slightly, install the electronic valve coil, restart, the air conditioner works normally, the electronic expansion valve is damaged, and the test machine is normal after many replacements.

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