I wouldn't have been able to fix my problem without the included links. Thanks for the info.
My passenger side drain for the sun roof was kinked (made of very soft hose, picture a gummy bear in Las Vegas in Summer). I was driving with the s/r slightly open in wet weather, so what happened was because the tube drained very slowly, water backed up and leaked over the sunroof drainage channel down the A pillar (or B on pass side?) and soaked the carpet.
*DISCONNECT BATTERY BEFORE WORKING ON THE CAR*
1) Make sure you have a sun roof. If not, the following won't work.
2) Get a cup of water and pour it into the drainage channels in your sun roof. Do one side at a time.
3) All the water should come out just behind both front wheels. (some may have 4 drains so check back wheels too) Water can leak into car by having the tube connection to the wheel well hole come apart, or tube kinked/blocked and it fills with water and it backs up into car through sun roof.
4) My pass. side tube was kinked, not blocked with debris. I first tried to see if it was blocked. Don't use a coat hanger as it could puncture the soft tubing & it's too short. I use an old electrical cord It needs to be 2+ feet.
5) If 4 doesn't work, sorry. Now comes the hard part. Loosen/remove inner wheel well cover. You'll see drainage hole. Try unplugging from that end.
6) That drainage hole is where the tube from the s/r goes through the wheel well. Some people have experienced that this connection breaks and the tube now drains into the car.
7) I went to the following sites. I replaced the tube with a sturdier and longer hose. The longer hose runs right out the wheel and hangs down behind the wheel well liner. No chance of kinking or popping off wheel well connection.
Has anyone replaced the sunroof drain tube - Nissan Forum | Nissan Forums
water/rain leak behind ecu, drain tube? - Nissan Forum | Nissan Forums
Thanks again to the authors and contributers of the above links.