Why does the car shake when the AC is turned on?
3 Answers
Opening the AC causes the car to shake for the following reasons: 1. Throttle: As the vehicle's mileage increases, carbon deposits accumulate in various places, especially on the throttle. If the throttle is dirty, it can obstruct air intake, causing the engine to struggle or barely manage to drive the compressor. This results in the car shaking when the AC is turned on. 2. Engine: The engine naturally vibrates during normal operation (including after starting the compressor), but these vibrations are usually dampened by the engine mounts, making them less noticeable. If the engine mounts collapse or are damaged, the engine's balance is disrupted, and turning on the compressor may reach a resonance frequency, intensifying the vibrations.
When I first started driving, I also encountered the issue of car shaking when the air conditioning was turned on. This is mainly caused by the compressor starting up and increasing the engine load. The engine has limited power at idle speed, and once the compressor kicks in, it requires additional power for cooling, making the engine work harder. If the car's ignition system is a bit old, the spark plugs might be carbon-fouled or the idle control valve dirty, making it more prone to shaking when the load suddenly increases. If the compressor itself is worn or loosely installed, the shaking can be even more severe. It's recommended to regularly clean the throttle body during maintenance and check the lifespan of the spark plugs for prevention. If the shaking persists for a long time without attention, not only will driving become uncomfortable, but fuel consumption will also increase, and there could even be safety hazards. Therefore, it's best to visit a reliable repair shop as soon as possible to identify the specific issue, such as whether the compressor bracket is functioning properly.
Engine shaking when the AC is on is quite common, especially in older models. The reason lies in the compressor momentarily drawing engine RPM when it kicks in. If the engine idle stabilization system has issues, the control system can't react quickly enough to the load change, causing the car to shake. Compressor activation creates a jolt similar to an impact, and the engine may vibrate more due to insufficient fuel or ignition timing deviation. Regularly check if your idle is smooth during driving, and perform simple self-checks on spark plugs and air filter condition. If shaking persists severely, it could indicate aging engine mounts or compressor failure needing attention. Addressing it early improves driving refinement, prevents damage to other components, and extends your vehicle's lifespan.
