What Causes Intermittent Engine Shaking When the Car Air Conditioner is On?
2 Answers
Intermittent engine shaking when the car air conditioner is on is generally caused by a dirty throttle body, which affects the engine. Below are specific details about a dirty throttle body: 1. When the air conditioner is turned on, the compressor also operates. Since the compressor is driven by the engine, its operation increases the engine's load. This increased load requires a greater throttle opening, leading to more air intake. If the throttle body is not maintained for a long time, carbon deposits can easily accumulate. These deposits obstruct the engine's air intake, making it difficult for the engine to drive the compressor adequately, resulting in idle shaking. 2. The throttle body needs to be cleaned. If the driving environment is harsh, it is advisable to clean it regularly—recommended every 10,000 kilometers.
Once when I turned on the AC, my car suddenly jerked, which was really annoying. Later, I asked a mechanic friend who explained that this mainly happens because the AC compressor requires extra engine power when starting up, just like how a person would pant when suddenly sprinting. If the engine has carbon buildup or worn spark plugs, the increased load makes it more prone to jerking. It could also be due to a loose or slipping belt, or unstable generator voltage. The most annoying part is that sometimes, when the car stops, there might be a vacuum tube leak, causing insufficient vacuum and making the engine unstable. My advice is to first check if the AC is aging. If the car has been running for a long time, regular maintenance like replacing spark plugs and cleaning carbon deposits can prevent these issues. But don’t try to fix it yourself—it’s best to have a professional check it out, since safety comes first. If something goes wrong on the highway, it could be dangerous. I remember working on a car recently—after replacing the spark plugs, the AC stopped jerking, and the car ran much smoother.
