Yellowish greenish is coolant. Double check those hose clamps for leaks.

 

You would only notice it when it snows and theirs enough on the ground in my case. Not on my G but my civ, and the ac is on everytime to defrost the front window. So it makes sense that it could be the ac fluid condensation or whatever leaks out. Not 100% but a good guess. Cause I have no leaks either or my neugbours altima. A good way to text this is to find out where ur ac leaks water and put a cup their and pour it in the snow and see if the colors match. Aint nobody got time for that.

 

Also coolant is located only in the front of the car where the engine is not in the middle or anywhere past the firewall. OP said its in the middle or exhaust area. No coolant runs in that area. That's y I suggest my theory