I’ve had a wet passenger side rear floor in my Accord for the past year now when I run the A/C. Two mechanics including a Honda dealership have told me the A/C drain is not plugged. One of them ran compressed air through the drain and it seemed to be better for about a week and then started again. Does anyone have any thoughts or suggestions for how to investigate the matter further. The floor does not smell like coolant. It just feels like and smells like water.
When it leaks, has it recently rained, by chance?
Maybe the ac drain became unplugged or is binding.
The drain tube itself may be perforated or disconnected somewhere.
Why is it in the backseat. Do you have a sunroof? If so it could be a drain line for it leaking water into the back seat.
I agree with @knfenimore. It is either a leaky sunroof or possibly a power window that is not functioning properly.
I will add the possibility that you are getting water because rain or condensation is getting in via the that big vent just in front of the windscreen.
Inspect the belt moulding on the door. I had a vehicle with a bad belt moulding, when it rained water ran down the glass into the door onto the carpet.
This is not a/c related but if this occurs when it rains it is a possibility.