I am a new owner of a 2002 ES300 and on the 1st long distance trip discover a lake on the rear passenger floor. I googled and found nothing for the ES300 that was helpful. So, this post might help others. Under the vehicle on the passenger side you will see a rubber grommet and a small hose should be sticking out. That will be the AC drain hose. That needs to be cleaned out. My problem was no hose was visible. I removed the grommet and stuck my finger in the hole and felt the hose. Needed a needle nose to get at it but once I pulled it out water began dripping. Problem solved. Hard pack snow or an ice chunk probably pushed the hose up in a kinked position.
