How much fuel does a car consume when running only the AC without moving for one hour?
2 Answers
Running only the AC without moving consumes 2.5L of fuel per hour. Below are the impacts of running the AC while the car is stationary: 1. Battery: While the AC compressor is indeed driven by the engine, the blower fan is powered by the battery. When the car is idling, it may not necessarily charge the battery. Excessive use of the blower fan can drain the battery, leading to long-term battery depletion. Driving at high speeds occasionally can help recharge the battery and maintain its health. 2. Engine: Without the AC, the air blown out utilizes waste heat from the engine, which is the principle behind the car's heating system in winter and does not involve the AC refrigerant. A handy tip: If the car's coolant temperature remains too high, indicating insufficient cooling from the front radiator fan, turning on the heating system can provide an additional cooling channel as an emergency measure. 3. Long-term effects: Prolonged idling with the AC on increases fuel consumption and engine carbon buildup, with the greatest harm being to human health. In a stationary state, the air inside the car does not circulate properly. Keeping the windows closed can lead to a false sense of comfort, causing occupants to fall asleep unknowingly, risking carbon monoxide poisoning or oxygen deprivation.
I have a habit of tinkering with cars in the garage and found that idling with the AC on for an hour does consume quite a bit of fuel, roughly fluctuating between 0.5 to 2 liters, depending on the engine displacement and AC settings. I personally tested my compact car with a 1.6L engine—during summer at max AC setting, it burned nearly 1 liter of fuel per hour because the engine had to keep running to power the compressor. For larger-displacement SUVs, fuel consumption is even higher, possibly exceeding 1.5 liters. Doing this long-term not only spikes fuel costs quickly but also leads to carbon buildup in the engine, affecting its lifespan. It’s advisable to avoid prolonged idling; for instance, turn off the engine while waiting roadside to save money, and regularly check AC efficiency during maintenance.
