Posted on 7/31/2026
Turning on the A/C should not make your car feel like it suddenly gained a trailer. A slight change in engine load is normal, especially in a smaller vehicle. Still, noticeable hesitation, weak acceleration, a rough idle, or stalling suggests the engine is struggling to meet the extra demand. The A/C compressor takes power from the engine whenever it runs. A healthy vehicle compensates by adjusting idle speed, fuel delivery, and throttle position. When another part is already weak, switching on the A/C can expose the problem almost immediately. The A/C Compressor Adds Load To The Engine The compressor circulates refrigerant through the A/C system. On many vehicles, it is driven by the serpentine belt, so the engine has to provide the power needed to turn it. That extra load is why you may hear the idle change slightly when the compressor engages. A small drop in power can be normal during hard acceleration, particularly with a low-horsepower engine. The concern beg ... read more