Reasons for Excessive Vibration When the Car Air Conditioner is On?
3 Answers
Reasons for excessive vibration when the car air conditioner is on are as follows: 1. Engine misfire: An engine misfire mainly refers to one or more cylinders not functioning properly, typically manifested as: intermittent exhaust gas flow, severe shaking of the exhaust pipe, noticeable engine vibration, and sometimes accompanied by a sputtering sound. This is often related to ignition coil failure. 2. Worn or loose engine mounts: Engine mounts are rubber blocks placed between the engine and the car frame. Their purpose is to reduce vibration and cushion the engine's operation while also securing the engine in place. Once these mounts become worn or loose, the engine's vibration will become significantly worse. Replacing the engine mounts can greatly reduce this effect.
I haven't owned this car for long, but whenever I turn on the AC, the vibration becomes particularly strong, especially at low speeds or when waiting at a red light—it feels like the entire steering wheel is shaking. The reason is that when the AC is on, the engine has to work harder to power the compressor, similar to how a person carrying a heavy load might walk unsteadily. If the engine's idle speed is already low, the compressor's mounting bolts are loose, or the engine mounts are worn out, the vibrations can become even more noticeable. Belt slippage is another common issue; over time, belts can loosen and slip, causing noise and vibrations. Last time I encountered this, I checked the belt myself and noticed some cracks—replacing it made a big difference. I recommend checking the belt tension once the engine has cooled down—safety first, don't wait until it breaks and costs a fortune to repair. Additionally, regular maintenance to clean carbon deposits can help; otherwise, the engine will shake even more, especially in city traffic with frequent AC use. In short, address these small vibrations early—don't ignore them.
I've been driving for over 30 years and have seen many cases of severe vibration when the AC is on. The most common issue is with the drive belt - if it's loose, deeply worn, or has debris on the pulley, it can slip when the AC starts, causing unstable engine RPM and strong vehicle vibration. This problem becomes more noticeable during hot summers when the AC is under heavy load. Additionally, worn compressor bearings or loose mounting brackets can worsen the shaking, which you can often diagnose by listening. Basic maintenance is simple: regularly check the belt's condition and maintain proper tension (too tight increases engine load). Replacing aging belts periodically effectively prevents such issues - don't neglect this, as safe driving is paramount. Excessive carbon buildup can also cause rough engine operation, especially noticeable as stronger vibrations at idle with AC on. I remember fixing this promptly when it happened to my car in my younger days.
