What Causes Significant Vibration in the Car When the Air Conditioning is Turned On?

[CooperLee]

The reasons for significant vibration when the car's air conditioning is turned on include: a dirty throttle body, poor fuel quality, ignition system issues, etc. Here are the details: 1. Dirty throttle body: If the throttle body is dirty, turning on the air conditioning will increase the engine's idle load, causing the steering wheel to shake. 2. Poor fuel quality: If the fuel quality is too poor, it can impair the engine's performance, leading to idle vibration issues. 3. Ignition system problems: If there is a fault in the car's ignition system, it can cause poor ignition system performance, weak spark plug firing, and other issues, resulting in unstable conditions like vibration during idle. 4. Excessive engine carbon deposits: If there is too much carbon buildup inside the engine, the fuel injected by the injectors during a cold start will be largely absorbed by the carbon deposits, leading to an overly lean air-fuel mixture during cold starts. This makes starting difficult and causes idle vibration after a cold start.