How to Solve the Shaking Issue When Turning on the Air Conditioning in a BMW 5 Series?
2 Answers
Solutions for the shaking issue when turning on the air conditioning in a BMW 5 Series include the following: 1. Severe Engine Carbon Deposits: The most common cause of car shaking is a dirty throttle body or excessive carbon deposits in the fuel injectors. When there is too much carbon buildup inside the engine, the gasoline sprayed by the cold-start injector is largely absorbed by the carbon deposits, resulting in an overly lean air-fuel mixture during cold starts. This makes starting difficult. In such cases, the car will only start easily once the carbon deposits have absorbed enough gasoline to reach saturation. After starting, the gasoline adsorbed on the carbon deposits is drawn into the combustion chamber by the engine's vacuum suction, making the air-fuel mixture too rich. The engine's combustible mixture alternates between being too lean and too rich, causing idle shaking after a cold start. 2. Ignition System Issues: Check the condition of the spark plugs, high-voltage wires, and ignition coils. Problems with the ignition system or poor performance of the spark plugs can also lead to such symptoms. 3. Unstable Fuel Pressure: If you have already cleaned the engine carbon deposits, cleaned the throttle body, and replaced the spark plugs but still experience shaking when starting, it is recommended to check the fuel supply pressure and the intake pressure sensor. Abnormal fuel pump pressure or incorrect readings and poor performance of the intake pressure sensor can all cause the car to shake.
I own a BMW 5 Series and have also experienced car shaking when the AC is on. I initially thought the AC was faulty, but later discovered it was due to aging engine mounts. The mounts couldn't handle the pressure when the compressor kicked in, causing the engine to shake whenever the AC was turned on. The solution was to replace the mounts, which cost a few hundred bucks to fix. I also regularly check the spark plugs and clean throttle body carbon buildup to reduce idle instability. Routine maintenance can prevent this issue—don't wait until the shaking gets severe to fix it. Now it runs much smoother, with no shaking even after hours of AC use. I recommend getting a professional shop to check your mounts—don't skimp on safety. After all, BMWs are well-built, and proper repairs make for a comfortable ride.
