Hi All,
I have a 2011 Versa Hatchback S MR18DE with about 120K miles. At about 60K miles we noticed that the carpet was soaked especially in the right rear. Bad moldy smell. Thinking that the ac condensation line was clogged I blew it out, didn't' seem clogged but the problem persisted. About 3 weeks ago I parked the car to start some extensive maintenance on the vehicle. In troubleshooting the a/c issue I noticed that the blower case develops condensation on the outside of the case which drips down on the the floor. Has anybody had this issue before? This one is new to me.

-mark

No, I have not noticed this before. Condensation on the outside of the AC assembly parts sounds unique. Your heater core is in there as well, with coolant inside. Does the moisture seem like it could be coolant? Still, I'm not sure how it would be on the outside unless it was condensation. Then, you say you have it in the back seats? I don't know how it could get there other than to completely saturate the front seat area and then seep to the back. That sounds like a lot of condensation to me. Like half a gallon or so.

I looked at the FSM manual air conditioning chapter. There is a drain line from the bottom corner. It is #7 in the picture on page 76 and or 77. I googled a bit and found a couple of owners found that their drain line hose was too short and or clogged. I can't see where the hose is supposed to go in the diagrams, but if you were there under your dash, I think you'd see it. Here's a link to that.
http://www.nicoclub.com/service-manual? ... a/2011/MTC

Also, I saw some people saying there might be a technical service bulletin about it, but I couldn't confirm in my searches. The number I got for that was NTB08-101a. Got any more information?

Central,
So this has been going on for sometime. I just now have a chance to work on it again. The first time I got the chance to work on it, I put it up on a rack, a blew out the drain hose. No gush of water, but the floorboards were wet; front but mostly right rear. Then I proceeded to pull the carpet up in the right rear passenger area. Puddle of water underneath the Styrofoam insulator. I dried that out, but the problem returned. I did wonder if the car was leaking at all, but I didn't notice any other wet spots after a big rain. So , I went back to the AC. I let it run for a bit with the AC on max and then started to feel around behind the dash. That's when I noticed condensation all over the blower case. That was 6 months ago. I haven't checked lately and I have parked the car to do some other maintenance on it now that I have the chance. Maybe it's a combination of things. I don't know. I probably will have to replace the carpet it is pretty moldy.

-mark

Do you have a moon/ sun roof? Those have a drain line as well for the sort of "gutter" around the seal perimeter. Here, someone talks about this drain line: has-anyone-replaced-the-sunroof-drain-tube-t575321.html. I wonder if that's not a contributor to your rear floor water. It doesn't sound like it from your description, but it may be worth investigation, since you're in there poking around already. Sorry to hear about the carpet. I hope you can find a reasonably priced replacement that fits well.

Yeah, no moon roof. i 'm gonna keep poking around and see if I get the same issue from the Blower Case. I bring back more information as I get it.

-mark

I'd be willing to bet there is some sort of a unibody leak in the right rear area.

amc49,
That is something I did look for earlier, but not closely. I was focused on the AC. But this time I will have the exhaust pipes down and will look much closer. Any known areas that I should pay attention to?

-mark

No known but that doesn't mean spit. Cars break in one-off miraculous ways all day long.

Reason for the idea being if that wet back there it should be soaked even more up front.

Dry the area well and then spray some water up under there with hose to test. Can be from front of rear wheel well too if missing cover.