How Long Can You Run the Air Conditioning with the Engine Off?
2 Answers
Generally, it is not advisable to run the air conditioning with the engine off for too long, with 15 minutes being the recommended limit. Prolonged use can lead to poor heat dissipation, which may damage the car's engine. Additionally, in relatively enclosed environments such as garages, there is a risk of carbon dioxide poisoning. It is best to use the air conditioning in open or well-ventilated areas and to leave a slight gap in the window. Below are the hazards of running the air conditioning with the engine off: 1. Poor air exchange between the inside and outside of the car when parked with the air conditioning on can lead to oxygen deprivation, which is harmful to health. The lack of proper air circulation in a stationary vehicle can cause occupants to unknowingly suffer from oxygen deprivation or poisoning while in a comfortable sleep state with the windows closed. 2. It is recommended that car owners who sleep with the air conditioning on leave a window slightly open. This is because the incomplete combustion of the internal combustion engine can release harmful gases such as carbon monoxide into the car. Sleeping in a parked car with the windows closed and the air conditioning on poses a risk of carbon monoxide poisoning. 3. When running the air conditioning while parked, it is crucial to ensure the location is open and well-ventilated. Never stay in the car for extended periods in enclosed spaces like garages to avoid exhaust gas poisoning. Additionally, use the external circulation mode to allow fresh air to replenish the interior.
As an experienced driver, I've personally encountered this issue. During a summer road trip, I parked by the roadside waiting for a friend, turned off the engine but left the AC on to stay cool. In just 30 minutes, the battery died when trying to restart, almost requiring a tow truck. I later learned that with the engine off, the AC only runs the fan—the compressor doesn't work, so there's no cooling. The fan still drains significant power: a new battery might last 40-60 minutes, while older batteries or high fan speeds deplete it faster. My advice? Don't risk it, especially in extreme heat—safety first. Running the engine ensures proper AC operation and prevents premature battery failure. Regular battery checks during maintenance also extend vehicle lifespan.
