What Causes Severe Vibration When Turning on the AC in an Old Honda Fit?
3 Answers
Severe vibration when turning on the AC in an old Honda Fit may be due to excessively large spark plug gaps, which would require replacement if found. Additionally, removing the air filter pipe to check if the throttle body is excessively dirty is recommended. If dirty, cleaning the fuel system should resolve the issue. Below is an introduction to the Honda Fit: Configuration: Equipped with Honda's all-new EDT engine, a 1.5L direct-injection DOHC-i-VTEC engine, CVT continuously variable transmission, Idle-stop engine energy-saving automatic start-stop system, VSA vehicle stability control system, three-mode rearview camera display system, ESS emergency braking warning system, HSA hill start assist system, intelligent screen interconnection system, and ten other advanced technologies leading its class. Environmental and Economic Performance: The third-generation Fit (FIT) adopts Honda's all-new "Earth Dreams Technology" powertrain system, maintaining high power output while reducing fuel demand, resulting in a fuel consumption as low as 5.3L per 100 kilometers, achieving the lowest fuel consumption in its class.
I drove an old Fit for ten years, and shaking when the AC is on is quite common because the engine load increases when the compressor is cooling. Older cars with more carbon deposits in the engine or a stuck/slow-responding idle control valve will shake when the RPM drops. If the spark plugs are worn, unstable ignition can worsen the shaking. Regularly clean the throttle body to avoid carbon buildup and check if the ignition coils are aged or cracked. Safety first—if the shaking is severe while driving, it's best to pull over and turn off the engine or seek nearby repairs. Long-term neglect can increase fuel consumption, damage engine components, and affect driving comfort and stability.
When the air conditioning is turned on in older Honda Fit models, the engine pressure suddenly increases, making it prone to shaking. The main reason is aging components due to the vehicle's age, such as eroded spark plugs or a weak battery causing unstable voltage. The idle control valve might be dirty and slow to respond, or there could be an air intake leak leading to an imbalanced air-fuel mixture. It's recommended to first check the condition of the spark plugs and try replacing them. A simple DIY check of the fuse box can also be done. If sudden shaking occurs while driving, don’t panic—turn on the hazard lights and pull over to address the issue. Regular maintenance is key for older cars, including periodic replacement of wear-prone parts to prevent unexpected issues.
