Is it okay to leave a sedan idling with the air conditioning on for a long time?
2 Answers
It is not recommended to leave a sedan idling with the air conditioning on for extended periods. When the engine is idling, the fuel does not burn completely, and the exhaust often contains a large amount of carbon monoxide. This carbon monoxide, expelled with the exhaust, can accumulate around the vehicle and enter the cabin through the air conditioning system. Additionally, with the windows closed while the air conditioning is on, the air does not circulate. Over time, the concentration of carbon monoxide inside the car can become dangerously high, posing a risk to human health. Additional relevant information is as follows: 1. Power consumption: The power output consumed by the air conditioning only accounts for a very small portion of the engine's idle energy. However, when idling with the air conditioning on, the engine not only drives the air conditioning compressor but also needs to maintain the normal operation of the power steering and brake booster pumps. The latter two functions are completely unnecessary when the vehicle is stationary, and keeping them running is a waste of power. 2. Idling: Idling is the minimum fuel injection strategy employed by the engine to ensure continuous operation. The engine is in a state of almost zero load, and idling is merely to maintain the continuous movement of the four strokes of the cylinder without interruption.
I've been driving sedans for over a decade, often idling with the AC on for warmth during cold winters. While it keeps the car comfortable, prolonged use has caused several issues. Once at a gas station while waiting for a friend, I idled with the AC on for half an hour and nearly ran out of gas—I had to push the car and ended up spending hundreds on repairs. When idling, the engine runs at low RPM with high load, increasing fuel consumption by at least 30%, raising pollutant emissions, and leading to carbon buildup, which causes engine shaking, shortens its lifespan, and reduces overall longevity. Now, I only use it briefly—like waiting a few minutes for someone—and shut off the engine immediately afterward, avoiding prolonged AC use. This saves money, protects the engine's health, extends its lifespan, and reduces unexpected breakdowns.
