Why is there hot air coming out when the car's AC is off?
1 Answers
When the air conditioning is turned off, hot air may still come out of the vents, which is particularly common in automatic AC systems. This occurs because, to maintain air circulation inside the cabin while the AC is off, the system automatically switches to external air circulation and foot vent mode. The negative pressure generated inside the vehicle while driving causes outside air to enter the AC system, creating a natural convection. The faster the car moves, the more noticeable this effect becomes, which is why you may feel warm air coming from the foot vents even when the AC is off. This is a normal phenomenon. Here are the regulation functions of a car's air conditioning system: 1. Temperature Regulation: This is the primary function of a car's AC. In summer, the cooling system produces cold air to lower the cabin temperature. In winter, except for large commercial vehicles that use independent combustion heaters for warmth, most vehicles utilize residual heat from the engine for heating. 2. Humidity Regulation: The humidity inside the cabin should generally be maintained between 30% and 70%. Standard car AC systems do not have the capability to regulate humidity; this can only be achieved through ventilation systems or advanced integrated heating and cooling systems found in luxury vehicles. 3. Airflow Regulation: When the temperature is comfortable, airflow speed should be limited to a certain range. The speed can be adjusted based on passengers' living environments, ages, health conditions, and personal preferences regarding warmth and coolness. 4. Air Purification: The quality of air inside the cabin is crucial for comfort.