You'll need to carefully inspect for coolant spills when the car is cold. Try squeezing the front hoses and look for drips. There are also 2 very short (hidden) hoses at the end of the front metal pipes that bring coolant two/from the engine block - need an inspection mirror to see them (passenger side, behind the fan blade, end of pipes).
The rear of the engine has two hoses (near battery) for the cabin heater system, it could be them? Or it could be one of the half dozen small hoses Nissan has scattered around the rear part of the engine. A small extension inspection mirror and flashlight might help to spot the trouble...