While driving, my Aviator started shaking violently. I frantically started turning everything off and when I turned the A/C off it stopped instantly. What might cause that?

Did the car start shaking when the A/C was first turned on or was it acting normally? It's probably something mechanical like Tom said.

The air conditioner was on and it started suddenly shaking while driving. Stopped immediately when a/c was turned off.

The air had been on and was working fine, started suddenly. Nothing unusual up to that point. Drove it several hundred miles after the water pump was replaced and everything had been working normally.

Did we ever find answer to this problem because mine is doing the same thing?