Why does the car air conditioner not cool when driving at high speed?
2 Answers
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.
I've been driving for years, and it's quite common to encounter the issue of the car's air conditioning not cooling well on the highway. The reasons can vary, such as insufficient refrigerant or leaks. At high speeds, the engine runs faster, and the compressor works more frequently, but the cooling effect can't keep up. There's also the issue of condenser heat dissipation—it works well at low speeds in the city, but at high speeds, increased airflow might block the condenser, preventing cool air from coming through. A dirty filter is another key factor; dust blocking the vents prevents cold air from flowing, so the temperature naturally doesn't drop. I remember last year when my car's AC wasn't cooling on the highway, a check revealed a loose compressor belt, and it improved after replacement. It's advisable to check the filter's cleanliness before driving and replace it regularly to ensure proper ventilation. If the problem persists, get it fixed at a professional shop promptly to avoid safety hazards. On the highway, keep the windows slightly open for ventilation to prevent heatstroke.
