Does idling the engine with AC on for half an hour damage the car?

[VonMiguel]

Idling the engine with the AC on for half an hour will not damage the car, but prolonged low-speed idling can significantly increase the likelihood of carbon buildup. The effects of engine carbon buildup are as follows: Carbon deposits can affect the operation of the fuel injectors, leading to poor atomization, which can disrupt the air-fuel mixture and increase fuel consumption. It can also reduce engine power, impair performance, and affect the spark plug's ignition timing, causing difficulty in starting and engine vibration. Precautions for idling with AC on: Avoid idling with the AC on in enclosed indoor spaces or with the windows tightly closed for extended periods, as this can easily lead to dangerously high levels of carbon monoxide inside the vehicle, which is far more serious than potential damage to the car.

[Jimmy]

I've been driving for over 20 years, and often hear people say idling with AC on for half an hour is fine, but it actually harms the car. When the engine idles, it runs slowly, leading to incomplete fuel combustion. Over time, this causes carbon buildup, clogging fuel injectors and cylinder heads, affecting performance and increasing fuel consumption. Running the AC puts extra load on the engine, and higher temperatures may cause cooling system issues, especially in summer heat—half an hour can drain the battery quickly. A friend of mine once spent a fortune cleaning carbon deposits due to frequent idling. While occasional idling is tolerable, it's best not to make it a habit. For long waits, park in the shade or turn off the AC and open windows to protect your car's lifespan.

[ElenaDella]

I drive to and from work every day, and in summer, I often idle with the AC on for half an hour while waiting. As a result, I noticed a significant increase in fuel consumption. At idle, the engine operates inefficiently, and running the AC engages the compressor, increasing engine load. This not only burns more fuel but also tends to accumulate impurities, forming deposits on the cylinder walls. The issues might not be obvious in the short term, but over time, the battery could also fail prematurely. A mechanic once reminded me during a repair. My current strategy is to turn off the AC after cooling for a few minutes or carry a portable mini fan to save money and hassle. A car is a big investment, so it's important to take good care of it.

[HarleyFitz]

I've been paying attention to car maintenance and believe that idling with the AC on for half an hour won't immediately damage modern vehicles' hardware. Engine designs are durable, and short-term operation poses minimal risks, though it can lead to carbon buildup that increases future maintenance hassles. Fuel consumption also rises significantly—half an hour of idling can burn 1-5 liters of gas, wasting money unnecessarily. From an environmental perspective, unnecessary emissions are harmful. I recommend adjusting habits, such as setting a higher temperature or turning off the AC intermittently while ventilating to maintain comfort.