Does idling with the AC on consume more fuel?
2 Answers
Idling with the AC on does consume more fuel. Running the AC while idling increases fuel consumption, and prolonged idling can accelerate carbon buildup. Over time, this may lead to symptoms such as engine shaking at idle, increased fuel consumption, and poor acceleration. Here are the details: Increased fuel consumption when idling with AC on: When the AC is on while idling, the engine not only needs to power the AC compressor but also maintain the normal operation of the power steering and brake booster pumps. The latter two functions are completely unnecessary when the vehicle is stationary, and keeping them running will increase fuel consumption. Idling with AC on accelerates carbon buildup: When a car remains idling with the AC on for an extended period, the vehicle's heat dissipation is poor, and the engine compartment temperature rises, causing the air-fuel mixture in the gasoline engine to become richer. This leads to uneven distribution of the air-fuel mixture in the intake manifold, preventing complete combustion of gasoline particles. As a result, large amounts of carbon monoxide are emitted, and carbon deposits form in the cylinders. Carbon buildup can disrupt the engine's air-fuel ratio, affecting not only fuel consumption and power output but also potentially causing engine damage.
As someone who's been driving for years, let me tell you, idling with the AC on really burns fuel. When the car is idling, although the engine runs at low RPM, it still needs to operate to power the AC compressor. The compressor requires energy to provide cooling, which comes entirely from burning gasoline. Based on my experience, a sedan consumes roughly 0.6 to 1 liter of fuel per hour, while an SUV might consume even more, depending on the model and AC settings. The fuel consumption isn't huge, but it adds up over time—especially with today's high fuel prices. Plus, prolonged idling can lead to carbon buildup in the engine. I recommend only doing this for short waits or when using the AC, keeping it under 15 minutes. When possible, turning off the engine and using the fan or rolling down the windows for ventilation is far more fuel-efficient than idling with the AC on, and it also reduces potential risks.
