Volvo Repair: 2000 Volvo c-70 convertible, volvo c 70, coolant level

Question
Robert, this one has stumped everyone that I've asked.  Hopefully you can help.  Over the past couple of months I've noticed that the floor behind the driver's seat, in front of the rear passenger is saturated with a greenish substance.  Had it looked at.  Turns out to be coolant.   approximately every two weeks my coolant level has been low and I've had to add to it to keep car from running hot.  Question is, what on earth could be causing coolant to leak in this area.  There are no other wet areas inside the car whatsoever.  Hope you can help.

Answer
The only path to the interior of the car for coolant is the heater core.It is accessed from the left side (drivers) underdash pad in the center column of the dash.Very common failure. Cant always tell it is leaking without disassembly, which is pretty easy. Only about 6 screws. The repair is way over priced, time wise. I've heard shops charging hours to replace. Takes about 20 minutes.