I have had this problem for nine months. You can hear the rattle very well from inside the car when you are on a bumpy road. It is a distinctive metal-to-metal rattle. It appears to becoming from the firewall area. The evaporator was replaced (VIP picked up the tab) about six months ago and I figured it would be tightened when they reassembled the dash...no such luck. When I roll down the windows I cannot hear anything. Any suggestions. I have checked the air ducks underneath the front seats. Thanks