What Causes Significant Engine Vibration When the Air Conditioning is Turned On in the Buick Excelle?
3 Answers
Significant engine vibration when the air conditioning is turned on in the Buick Excelle can be caused by a dirty throttle body or collapsed/damaged engine mounts. Below are detailed explanations: Dirty Throttle Body: As the vehicle accumulates mileage, carbon deposits can build up in various areas, particularly the throttle body. If the throttle body is excessively dirty, it can obstruct air intake, leading to insufficient engine power to drive the compressor smoothly, resulting in noticeable engine vibration when the AC is on. Cleaning the throttle body is the solution, typically recommended every 20,000 kilometers. Collapsed or Damaged Engine Mounts: Even during normal operation, the engine produces vibrations (including when the compressor is engaged), but these are partially dampened by the engine mounts, making the vibrations less noticeable. If the engine mounts are collapsed or damaged, the engine's balance is disrupted, potentially causing resonance when the compressor is activated and amplifying the vibrations. It is advisable to visit a 4S shop for repairs.
I also experienced a similar situation with my Excelle. When the AC is turned on, the engine noticeably shakes, which is quite concerning. This is usually because the AC compressor requires engine power to start, causing a sudden increase in load. If the engine already has minor issues, it can easily become unbalanced. Common causes include aging spark plugs, ignition coil failures leading to uneven combustion, or a dirty throttle body affecting air intake efficiency. Carbon buildup on the idle control valve can also worsen the instability. Additionally, aging engine mounts can make the vibrations more noticeable—gently shaking them to check for looseness is recommended. For prevention, regular maintenance is key, such as replacing the air filter every 20,000 kilometers, cleaning the throttle body, and using high-quality fuel to reduce carbon deposits. If the shaking persists, it’s safer to visit a professional shop promptly to check the compressor or ignition system. Shaking while driving may affect control, so addressing it early prevents minor issues from becoming major ones.
Having worked on many cars, I'm quite familiar with the shaking issue when the Excelle's AC is on. When the compressor is running, it increases the load, so the engine idle needs to be stable. Otherwise, worn spark plugs or poor ignition can cause combustion vibrations. A clogged air filter restricting airflow is another factor, and carbon buildup on the throttle body makes it sluggish. Cracked rubber mounts directly transfer vibrations to the body. Start by scanning for trouble codes with a diagnostic tool to save time and effort. If you're DIY-inclined, checking and replacing eroded spark plugs is straightforward, and cleaning the throttle body with carb cleaner spray helps. For clogged fuel injectors, try adding a fuel system cleaner. Mounts are cheap to replace and reinforce. Regular maintenance is key—change the oil every six months to prevent carbon buildup. If the compressor's electromagnetic clutch is slipping or making noise, it's safer to get it professionally repaired. Don't delay; worsening shakes make driving unstable and prone to accidents.
