What Causes Car Vibration When Braking with Air Conditioning On?
2 Answers
Here are the specific reasons for car vibration when braking with air conditioning on: 1. Suspension system failure: The suspension system is mainly responsible for filtering engine vibrations during operation. If there is a problem with the suspension, these vibrations will be directly transmitted to the steering wheel and the cabin, affecting driving. When the engine is idling, turning on the vehicle's electrical system can also easily cause vibrations. The engine increases its load due to the electrical system being turned on, causing the idle speed to drop. To compensate for the vibration caused by the idle speed drop, the engine will automatically increase the speed. When turning on the electrical system, especially the air conditioning, the engine often vibrates. This vibration is likely caused by aging suspension components and requires timely replacement. 2. Unstable oil pressure: If the engine carbon deposits have been cleaned, the throttle body has been cleaned, and the oil pads have been replaced, but the car still vibrates, it is recommended to check the fuel supply pressure and the intake pressure sensor at a repair shop. If the fuel pump supply pressure is abnormal or the intake pressure sensor values are incorrect or malfunctioning, it can cause car vibration. 3. Cold start: The main reason for car vibration during a cold start is insufficient fuel combustion, resulting in insufficient power. The ignition energy is relatively low, and when starting, with lower temperatures of fuel and lubricating oil, more throttle is needed to meet the power demand. Over time, the gap between the spark plug electrodes gradually increases, leading to decreased ignition energy and poor fuel atomization, which causes car vibration. Additionally, aging ignition coils, aging spark plug high-voltage wires, or leakage can also reduce ignition energy.
As a veteran driver with over a decade of experience, I'm quite familiar with car vibrations when braking with the AC on. This is usually caused by the AC compressor engaging, which increases engine load and leads to unstable idling. Naturally, the lower the engine RPM, the more pronounced the vibration. When braking, the vacuum booster system consumes vacuum to assist braking. If the AC also draws vacuum, the brake pedal may feel stiff, and vibrations could intensify. This issue is especially noticeable in older vehicles where the engine mount rubber has aged or cracked, reducing its ability to dampen vibrations. My old Santana had this problem, which improved immediately after replacing the mounts. Paying attention to the difference in engine idle with the AC on or off can help diagnose the issue early. Otherwise, it's best to visit a professional shop for inspection to avoid safety hazards.
