I received some questions to my email from some people having the same problem. I solve the problem in my van, it was a bad water pump. The water pump diaphragm broke and leak water, that was the reazon for water loss from the radiator cooling system. I wasn't able to see the problem because the system was filled with water and can be mistaken with the water that the air conditioning system drop under the van. Once I charge the system with coolant, I was able to see that the water that drop under the van was not from the air conditioning, was from the radiator system because was green in color. I track the path of water to the main pulley, The pulley that drives all the belts, is the lowest pulley. If you have the same problem you may change your water pump, and is not so easy, you have to remove the cam shafts pulley covers, belts, mainshaft pulley and some harnesses to get to the place where the pump is, is the same way you may change your timing belt. Then, you have to follow step by step the air bleeding proccess, that the more tricky part of the repair proccess. Be shure that you have a working thermostat, a fine working electric fan ( is 2 speeds ), check if the 2 speed are working, check the harness plug, I fund mine burned because this is a high current fan. Check for leaks in the heaters lines, can be corrected with a heatproof hose and 2 clamps. Some times a big problem have different combined sources. I had problem with the fan, the heater lines and the pump, all at the same time, that's why I was crazy about the problem, I was looking for one broke part, not for multiple broke parts. In a system like this when a part failure, can make another part to failure. I hope I can help someone with this follow up. And don't be shy, write here what else you found to solve this problem, that way we can help another Nissan Quest Users.
Thanks !