Hi, I have a 97 accord ex with 50k miles. I had my timing and ac belts changed a month back. I onlu used the AC once or twice after that but yesterday when I turned on the AC I realized that when I start the AC the car vibrates a bit and than it seems that the vibrations either disappear or become a part of the car cuz overall the car seems more shaky (not too sure about the latter comment). Any ideas? There is one more strange part which is that even when the car is turned off, sometimes a noise comes from the hood like some diagnostic test is being done and that is the strangest thing I saw yesterday. What could that be? Thanks, Wajahat