Does leaving the car running with the AC on consume more fuel?

[DeJames]

Yes, it consumes more fuel. When the car is idling without moving, it indicates the engine is in an idle state, which leads to increased fuel consumption. Here are some precautions regarding using the AC: 1. Random AC airflow direction: Adjusting the airflow direction randomly affects the interior temperature. If the AC airflow is set randomly, the cold air will cool down high-temperature components that don't need cooling, offsetting the cooling effect and reducing its efficiency. 2. Keeping the recirculation mode on for too long: Many drivers keep the recirculation mode on to save energy, which does reduce the compressor's activation frequency. However, prolonged use can make the air inside the car stale and reduce oxygen levels, leading to dizziness or even hypoxia for passengers. 3. Avoid running the AC while parked: Running the AC while the car is parked is very dangerous. When the car is idling or moving at low speeds, gasoline doesn't burn completely, producing carbon monoxide. If the AC is in fresh air mode, it will draw carbon monoxide into the car, potentially causing carbon monoxide poisoning. It's best to switch to recirculation mode.