Why does the car air conditioner not cool when driving at high speed?

[ElainaLynn]

When the car air conditioner does not cool properly during high-speed driving, the general cause is a malfunctioning expansion valve: 1. When the expansion valve is blocked: The refrigerant cannot flow smoothly in the air conditioning system, eventually leading to excessive pressure. Normally, the air conditioning compressor is driven by a belt, so theoretically, the higher the speed, the better the cooling effect should be. However, when there is moisture in the refrigerant, it can easily freeze at the expansion valve due to the high speed and high cooling power, causing blockage. This results in increased air conditioning pressure, leading to a loss of cooling. 2. Excessive sensor pressure: If the air conditioning pressure sensor detects excessively high pressure, it will stop the compressor from working. This is why the air conditioner stops cooling when the car is driven at high speeds.