your heater core is going bad
I had the same problem with my caprice a few weeks back. The water shouldn't be dripping from the back, it should be dripping on the rear passenger side floor board. That is caused by the heater core being bad, which is causing the water to seek through the carpet and drip out the back floor board.
Right above the drivers side floor board under the dash.
under driver's floor board. there is a hole in the floor to fill it.
i am looking for drivers side floor pan 1980 camaro ---- http://www.classicindustries.com/camaro
The computer is right above the floor board on passenger side under the dash.
the ducts can not be hooked up for the vents to work
jackson pollock
under the right floor board just in front of the seat under a latch cover.
Jack up the motor and replace them. Center of the motor on the sides. Use a block of wood on a floor jack and lift on the oil pan,
Distance from the floor to the base of the back board
Check for a sickly sweet smell. The heater core is probably leaking coolant into the floor. The core is not repairable but can be replaced.
Either have air in your lines or you might need a new clutch plate.