Ok so I know there have been alot of posts about leaking evaporator cores in the forums but I think I might have something entirely different going on. My prius is leaking quite heavily from inside the cabin but I'm pretty quick to dismiss the whole evaporator clog/leak theory because of one simple reason: its leaking everywhere EXCEPT the passenger side floor! That's where the drain is for the evaporator and yes, I have cleaned out that tube as much as is humanly possible. I've tried using a small pipe snake, a wet/dry vacuum and other steps to make sure it isn't that drain that's clogging up but still .... my problem remains. It would make sense that if the source of my leaking problems is the evaporator that it would stem from the passenger side area where the drain is and then migrate to the rest of the floorboards but that simply isn't the case. The passenger side floorboard is about the only thing that is DRY in the whole car. Basically the floor of the driver's, driver's rear and passenger's rear side are so completely soaked with what I can only hope to be water that there are visible (and smelly) puddles of water/condensation/whatever it is. I have soaked up all that I can with towels and dried out the rest hoping that cleaning out the drainage tube would have solved the problem but it just keeps coming back! Much like many of you that have had leaks in the cabin this only happens when it is humid/raining. Every other normal day the A/C and heater are running exactly as they should be and there is no leakage whatsoever but the second it rains, bam, puddles! I have looked everywhere I can for a possible source of incoming rain water but I can't find any holes, cracks, perforations or anything of the sort. The problem may be coming from underneath the car where I can't see but I have a feeling it might be from what my mechanic grandfather tells me is the radiator for the heater. Now I don't know enough about the prius to know if it even has one but he's worked on several cars for many years and he says that that definitely might be the problem: that the radiator for the heater is leaking its discharge into the cabin. Is this the case? Are there drainage tubes I don't know about underneath the spots I mentioned above? I notice that when I turn off the car and let it rest for a bit I do see little drips of water coming from the exact places where the water is gathering most in the cabin. Problem is, where's it coming from? Outside in? Inside out? Anyone else have this problem? Oh and just in case your wondering, yes, the floorboards (and consequently the carpet touching the floorboard, not the transmission hump) are the only things wet. The seats, roof, dash, hatch, seat belts, etc. are all completely dry.