Are you sure that what you think is the smell of coolant is not just the smell of wet carpet/sound proofing absorbed into the water.I've thought of the screen, I've also had a good look around to make sure there aren't any unexpected holes or missing plugs in the floorplan - nothing.
I'm only talking a small damp patch, not a puddle but as I say, the unmistakeable whiff of coolant is what is bothering me.
Everything else is fine, blower temp, all vents operate correctly.
Check the aircon drains first as it won't cost a penny if that is the problem.
I still can't find them.... I need a map or something... What do they look like?