Teddd

My wife was driving the 95 LS 400 home yesterday with the AC on. While she was at a red light, she heard and felt a strong vibration. At first she thought is was heavy equipment nearby, but quickly realized it was the car. The first thing she did was turn off the AC. The vibration stopped. After continuing on from the light, she turned the AC on again and it was fine. I looked under the hood when she got home and everything seemed normal. I'll keep an eye on it, but has anyone had this happen??