Just recently I noticed coolant collecting in the passenger side floor. It's hard to trace exactly how it got there and where it came from. Is there a chance my heater coil had ruptured somehow?

 

Is it actually cooant (greenish yellow and smelly) or just wet? If it is more like water, see the other thread--it is likely the AC condensate line backing up. It could also be a leak through the fresh cabin air intake.

If it is definitely coolant, than I would look at the heater.

 

what he said