What Happens If You Leave the Car AC On All Night?

[DeDonovan]

Leaving the car AC running all night while the engine is on can cause damage to the vehicle. Here is relevant information: Introduction to Car Air Conditioning: The car air conditioning system consists of a compressor, condenser, throttle element, evaporator, fan, and necessary control components. It is designed to regulate the temperature and humidity inside the car, providing a comfortable environment for the driver. Working Principle: When the compressor operates, it draws in low-temperature, low-pressure gaseous refrigerant from the evaporator. After compression, the refrigerant's temperature and pressure increase, and it is sent to the condenser. Inside the condenser, the high-temperature, high-pressure gaseous refrigerant transfers heat to the outside air passing through the condenser, causing it to liquefy into a liquid. The liquid refrigerant flows through the throttle device, where its temperature and pressure decrease, and then enters the evaporator. Inside the evaporator, the low-temperature, low-pressure liquid refrigerant absorbs heat from the cabin air passing through the evaporator, evaporating into a gas. The gas is then drawn back into the compressor for the next cycle.

[EleanorAnn]

I had a similar experience before. That time, I parked by the roadside waiting for someone and fell asleep from exhaustion, forgetting to turn off the air conditioning. As a result, the car wouldn't start the next morning—the battery was completely drained, and I had to get a jump start to resolve it. Later, I learned that the continuous operation of the air conditioning compressor consumes a significant amount of power, especially if the engine is idling, which also leads to high fuel consumption. After a whole night, the fuel tank could be noticeably lower. Nowadays, some new cars come with automatic protection features, such as turning off the air conditioning after running for a certain period to prevent such situations. I recommend installing a mobile app to remotely monitor the vehicle's status to avoid repeating the mistake. For safety reasons, it's best not to stay overnight in the car with the air conditioning on.