What Causes the Expansion Valve to Freeze in the Passat Lingyu?

[DelAbel]

Passat Lingyu expansion valve freezing is caused by insufficient refrigerant, expansion valve malfunction, or evaporator temperature sensor failure. Below is a detailed explanation of the causes: Insufficient Refrigerant: Insufficient refrigerant leads to reduced air conditioning cooling efficiency, resulting in expansion valve freezing. It is recommended to add refrigerant. Expansion Valve Malfunction: When the expansion valve throttles too severely, it can cause the pipeline to freeze, necessitating replacement of the expansion valve. Evaporator Temperature Sensor: If this sensor fails and does not provide timely protection, the compressor continues to operate, leading to overcooling and freezing. The sensor needs to be replaced.

[DelAna]

I think icing of the expansion valve is quite common in the Passat Lingyu, mainly due to excessive moisture accumulation in the air conditioning system or improper refrigerant charging. The expansion valve is a component that regulates the flow of refrigerant. If it becomes clogged or moisture isn't properly removed, the temperature of the low-pressure gas passing through can drop sharply, leading to icing. The result is poor air conditioning cooling performance, reduced airflow from the vents, and abnormal compressor operation. I've dealt with similar issues before, mostly caused by incomplete vacuuming during previous repairs or desiccant failure absorbing moisture. It's advisable to promptly visit a professional shop to check system pressure, replace the desiccant, and properly recharge the refrigerant. Don't delay too long, as compressor damage will be more expensive to repair. Pay attention to the air conditioning's performance while driving, and avoid running the A/C for extended periods at idle. Regular maintenance can prevent such issues, and it's best to have a check-up before summer.

[SanKaden]

I believe the icing of the Passat Lingyu's expansion valve is usually caused by two key issues: first, excessive moisture in the air conditioning system, and second, abnormal refrigerant flow. Once the expansion valve ices up, the air conditioning stops working, causing uncomfortable temperature fluctuations in the car. I've driven this car and encountered a similar situation. Later, I learned that the previous refrigerant recharge wasn't done properly, leaving moisture inside that froze the valve opening. The mechanic recommended replacing the desiccant and performing a vacuum recharge to fix it. This issue is not trivial—delaying repairs can increase fuel consumption and damage the compressor. For prevention, I suggest avoiding the use of the external air circulation mode in rainy or humid conditions and ensuring the air conditioning system is serviced at least once a year. Checking the refrigerant pressure can also help detect problems early. The repair isn't too complicated and usually costs a few hundred yuan.

[VanChloe]

To deal with a frozen expansion valve, I believe the first step is to measure the air conditioning system pressure. If the low pressure is too low and causes freezing, it may be due to moisture blockage or insufficient refrigerant. It's best to release the old refrigerant, vacuum the system to remove moisture, and then recharge with the appropriate amount of new refrigerant. Next, check if the desiccant canister has failed and replace it promptly. If the expansion valve itself is damaged, it needs to be replaced with a new one—just choose the matching model for the Passat. After repairs, test the cooling effect to ensure the compressor is functioning properly. Don't attempt DIY fixes; a professional shop can resolve it quickly. Preventive measures include maintaining system sealing to avoid refrigerant leaks. Before parking daily, turn off the AC to allow the system to balance, which can reduce risks. Repair costs aren't high, but delaying will cost more in the long run.