How much fuel does a car consume when running the air conditioning for one hour?
2 Answers
For a typical family sedan, running the air conditioning for one hour consumes approximately 1-3 liters of fuel. The car air conditioning system operates through four cyclical processes: 1. Compression process: The compressor draws in low-temperature, low-pressure refrigerant gas from the evaporator outlet and compresses it into high-temperature, high-pressure gas before discharging it from the compressor. 2. Heat dissipation process: The high-temperature, high-pressure superheated refrigerant gas enters the condenser, where it condenses into a liquid due to the reduction in pressure and temperature, releasing a significant amount of heat. 3. Throttling process: The higher-temperature and higher-pressure refrigerant liquid passes through the expansion device, causing its volume to increase and its pressure and temperature to drop sharply, exiting the expansion device as a mist (fine droplets). 4. Heat absorption process: The mist-like refrigerant liquid enters the evaporator. Since the boiling point of the refrigerant is much lower than the temperature inside the evaporator, the refrigerant liquid evaporates into a gas, absorbing a large amount of surrounding heat in the process. The resulting low-temperature, low-pressure refrigerant vapor then re-enters the compressor. These processes repeat continuously to achieve the goal of lowering the temperature of the air around the evaporator.
From my driving experience, running the air conditioning for about an hour consumes an extra 0.5 to 1 liter of gasoline. The exact amount depends on the car size—small-displacement cars use around 0.4 liters, while large-displacement SUVs can go up to 1.2 liters. The hotter the weather, the harder the AC works, increasing fuel consumption. In city traffic with frequent stops, AC usage spikes fuel consumption, whereas highway driving is slightly more efficient based on my multiple tests. I recommend setting the temperature around 26°C instead of too low, and ventilating the car by opening windows for a minute or two before turning on the AC to reduce fuel usage. Regularly check the AC system for refrigerant leaks, as this can lead to higher fuel consumption—ignoring this could cost more in the long run. Staying proactive saves money and ensures peace of mind.