Does idling with the AC on in summer consume more fuel?

[Camargo]

Idling with the AC on in summer does consume more fuel. Running the AC's cooling function while the car is idling leads to increased fuel consumption. Prolonged idling can also accelerate carbon buildup, which over time may cause symptoms like engine shaking at idle, increased fuel consumption, and sluggish acceleration. Relevant details are as follows: 1. Running the AC while idling: The engine needs to power the AC compressor, water pump, oil pump, etc., but only the AC compressor is actually working. This results in wasted energy, leading to higher fuel consumption. 2. When the AC is cooling: The engine must drive the compressor, which consumes a portion of the engine's power. Keeping the AC on for extended periods while idling does indeed result in significantly higher fuel consumption.

[JohnFitz]

I have to say this is indeed quite fuel-consuming! I've personally experienced it during summer when waiting in the car. The engine has to keep running to power the air conditioning compressor, and at idle speed, the fuel consumption is at least 1.5 liters per hour. If you're driving an ordinary family car, one hour of air conditioning can easily burn over ten yuan worth of fuel. What's more troublesome is that prolonged idling can easily cause carbon buildup in the engine, which means spending more money on cleaning during the next maintenance. So, I usually turn off the engine if I have to wait for more than half an hour, roll down the windows for some fresh air instead—it's more cost-effective. If it's really unbearably hot, I'll turn on the air conditioning for 15 minutes and then turn it off to cool down.

[Tiffany]

As someone who frequently drives long distances, I've tested this firsthand. Idling with the AC on consumes way more fuel than you'd expect – a 1.6L engine can burn nearly 2 liters per hour! The bigger issue is engine damage. At idle, combustion efficiency drops significantly, leading to incomplete fuel burn that causes carbon buildup on valves and spark plugs. My friend's car actually threw a fault code from doing this. My advice: avoid napping in parking lots with the AC running. If you need rest, park in the shade with windows down or invest in a solar-powered vent fan for your window – keeps you cool while saving fuel.

[Lillian]

Honestly, this practice wastes both fuel and the car. I've seen too many cases in the repair shop where long-term idling with the AC on leads to severe carbon buildup. When the engine RPM is too low to power the AC, it burns fuel like crazy. For small-displacement cars, running the AC for an hour is equivalent to driving 20 km for nothing. My personal habit is to open the windows for ventilation for three minutes before turning on the AC, which cools faster and saves fuel. If I'm waiting in the car for more than 20 minutes, it's more economical to turn off the engine and get out, rather than watching the fuel gauge drop while enjoying the cold air.