What is the fuel consumption when idling with the air conditioning on?

[VanRicardo]

Idling with the air conditioning on consumes approximately 1.4-2.5 liters of fuel depending on the engine displacement, with an average of around 1.6 liters. Below are the four cyclic processes of a car's air conditioning system: 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. 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, where its volume increases, and its pressure and temperature drop sharply, exiting 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 gas, absorbing a large amount of surrounding heat in the process. The low-temperature, low-pressure refrigerant vapor then re-enters the compressor. These processes repeat continuously to achieve the cooling of the air around the evaporator.

[MilesDella]

I understand how the car system works. When you run the air conditioning in neutral, the engine is idling and doesn't need to drive the wheels, but the AC compressor increases the engine load, leading to additional fuel consumption. Typically, this consumes an extra 0.2 to 0.5 liters of fuel per hour, depending on your car's engine size, AC settings, and ambient temperature. For example, a 1.6L car running the AC on a hot day might burn an additional 0.3 liters of fuel. This is a waste of resources because the engine already consumes base fuel in neutral, and adding the AC makes the fuel tank deplete faster. Additionally, this increases exhaust emissions, which is bad for the environment, and may also lead to engine carbon buildup or reduced component lifespan. In daily driving, I recommend using the AC only while driving, as this balances the engine load better, optimizes fuel consumption, and reduces unnecessary costs.

[LeDawson]

As a seasoned driver with years of experience, I've tried idling in neutral with the AC on during summer red lights or roadside breaks, only to quickly notice increased fuel consumption. It burns about 0.25 to 0.4 liters more per hour, especially noticeable at higher AC settings. That one-hour wait in the parking lot visibly dropped the fuel gauge by a notch. It's not just costly—it also puts unnecessary strain on the engine, increasing wear risks. I'd say this habit is uneconomical and should be minimized, reserved only for short-term emergencies. When running the AC while driving, higher engine RPMs make the system more efficient, with significantly less fuel impact while maintaining cabin comfort. To manage expenses, cultivate the habit of avoiding prolonged idling with AC.

[BrantleyMarie]

As a car owner who drives frequently, I pay close attention to fuel consumption management. Running the air conditioning in neutral gear definitely increases fuel consumption because the engine has to drive the compressor while idling, consuming an additional 0.2 liters or more per hour. This not only adds to expenses but also poses safety risks, such as rapid battery drain or overheating issues. I've recorded in my own car that running the air conditioning in neutral with cold air for an hour can consume nearly half a liter of fuel. A smarter approach is to use the air conditioning only while driving, when the engine operates efficiently, balancing the load and reducing waste. When parked, it's best to turn off the air conditioning, open the windows for ventilation, or minimize waiting time. Consistently saving fuel this way not only saves money but also reduces unnecessary environmental pollution, making driving more sustainable.

[KylieDella]

I am very sensitive to environmental issues. Running the air conditioning in neutral gear increases fuel consumption and emissions, which requires vigilance. Typically, it consumes an additional 0.2 to 0.4 liters of fuel per hour, equivalent to emitting more exhaust pollutants. This is a waste of resources, especially when idling purely for comfort during parking. In my daily travels, I have observed that running the air conditioning while the engine is idling not only wastes fuel but also accelerates heat buildup, which is unfriendly to the environment. We should advocate using the air conditioning only when the vehicle is moving or during brief stops to reduce unnecessary fuel consumption. Choosing to park in well-ventilated or shaded areas can also reduce reliance on air conditioning, saving energy for the planet. Simple changes in habits can make driving more eco-friendly.