Volvo backseat floor SOAKED when I run the A/C. What is the problem???

[kid_mayhem36]

I have an 05 volvo s60 2.5 AWD. When I run the A/C the REAR driver side back seat floor is SOAKED. I have found the front passengers side A/C drain tube and it is clear. How do I clear the tube for the driverside backseat floor? Where is it located? How hard is it to get to? How do I go about clearing it? Is that even the problem? Any and all responses are appreciated!!!!!!!!