1. Blockage

• ​​Ice Blockage​​: Caused by moisture in the system, which freezes at low temperatures to block the valve orifice. This leads to reduced cooling efficiency or intermittent failure to cool. The ice may melt temporarily after shutdown, restoring partial function.
• ​​Dirt Blockage​​: Accumulation of impurities (e.g., welding slag, oil contamination) at the valve port restricts refrigerant flow. Symptoms include uneven frosting or no frosting on the evaporator, condensation/frosting on the valve body, and insufficient cooling.

2. Abnormal Valve Opening/Closing

• ​​Insufficient Opening​​: Inadequate refrigerant flow causes high evaporator temperatures, low suction pressure, poor cooling performance, and condensation/frosting on the valve body.
• ​​Excessive Opening​​: Excessive refrigerant flow leads to thick frosting on the evaporator, high suction pressure, and potential compressor liquid hammer (wet stroke).

3. Temperature Sensing Bulb Malfunctions

• ​​Improper Installation​​: If the temperature sensing bulb is not tightly attached to the evaporator pipe, temperature sensing errors occur, resulting in faulty valve regulation.
• ​​Leakage or Damage​​: Leakage of refrigerant inside the sensing bulb prevents pressure signal transmission, causing the valve to close or fail to adjust, leading to system cooling failure.

4. Electronic Expansion Valve Faults (Intelligent Systems)

• ​​Motor Jamming/Damage​​: The valve needle cannot move properly, causing uncontrolled refrigerant flow. Common in variable-frequency air conditioners, this results in abnormal cooling/heating performance.
• ​​Abnormal Control Signals​​: Malfunctions in the circuit board or sensors lead to mismatched valve opening with system load, increasing energy consumption or reducing efficiency.

5. Valve Body Damage or Leakage

Cracks in the valve body, loose connections, or other issues cause refrigerant leakage, reducing system pressure and cooling capacity. Leakage can be detected using a leak detector.

6. Impacts

• Reduced cooling efficiency and increased energy consumption;
• Abnormal system pressure (excessively high high pressure or excessively low low pressure);
• Compressor damage (e.g., liquid hammer, wear).

Maintenance Recommendations

Professional personnel are required to identify the type of blockage, replace damaged components, or readjust the valve opening. Self-disassembly should be avoided to prevent system contamination.