Have a Car Question? Ask a Mechanic Online.
My name is XXXXX XXXXX I will be helping you with your issue. If you are running the defroster, the ac system will engage. This is because the AC causes all the moisture in the air to condense into liquid , making the air dry when it comes out. The fans will always run when the AC is engaged. You can double check by disabling the heat and AC and then seeing if it engages as well.
The water noise you hear could be two things. Water does build up in the ac unit while the car is running, this is normal, and it drains out. The drain can clog, usually this shows as a wet spot in the drivers or front passenger's foot-well. The other thing it could be is the refrigerant itself in you cooling system. Once the AC system is disengaged, the coolant that is still cold "boils" (this happens at 33*F) this sound can sometimes be heard, and it may be louder if the refrigerant is a little low.
So try disengaging/deactivating all climate control prior to starting the vehicle then start it and see if your issue occurs. Let me know if it is still happening.
If my answer(s) helped solve your questions, please rate it!