Wet passenger side floorboard

[2006LR3]

Hi -

I own a 2006 Land Rover LR3 V8 HSE. The problem is the passenger side floor board gets wet after turning on the air conditioner. I have read some other problem solving post, and to date I believe the problem is caused by a clogged drain tube.

Can anyone tell me the best way to locate that drain tube, and then unclog it. Or if that may be the problem?

Thanks in advance.