Before talking about whether it is good or bad, let’s talk about the working principle of the electronic expansion valve: its function is to use a special stepping motor to drive the valve core to adjust the refrigerant flow.
The inspection methods of the electronic expansion valve are as follows:
1. Measure whether the coil of the motor is open;
2. Is there any driving signal added?
3. Does the opening change after adding the drive signal? Only through comprehensive testing can these technologies make correct judgments and select a good electronic expansion valve.
First of all, the ideal working state of the electronic expansion valve should be to change the opening degree in real time and control the flow with the change of the evaporator load. But in fact, due to the hysteresis of heat transfer in the temperature sensed by the bulb, the response of the electronic expansion valve is always half a beat slower. If we draw a time flow diagram of the electronic expansion valve, we will find that it is not a smooth curve, but a zigzag line. The quality of the electronic expansion valve is reflected in the amplitude of the twists and turns. The larger the amplitude, the slower the response of the valve and the worse the quality.
Secondly, the electromagnetic coil is on, the electronic expansion valve has a sound of action after receiving the switch command, and it is judged from the system state parameters that the expansion valve action is effective. During normal operation, there is no obvious abnormality in the pipeline behind the electronic expansion valve. Explain that the electronic expansion valve is good.
Finally, the failure rate of the electronic expansion valve itself is very low, and it is a component that is not easily damaged. Most electronic expansion valve failures are caused by dirty blockage, ice blockage, or abnormal solenoid coils.