Hey, I just bought an 05 aveo sedan, little golf cart. Sounds like there are a few gallons of water sloshing around in the dash. My brother is an awesome Chevy Mech, owns and rebuilds lots of Heavy Chevys, he said water in the heater core...but I am not sure I can mess with that, but he also said ac drain may be clogged...I'd have him find the drain for me, but he's in FL and I'm in NY
Anyone able to tell me where it is located on the 05? He said if run ac and no water drops out under car it may be clogged

 

Check your radiator fluid level. Our suburban sounded like that when the water pump developed a slow leak and the coolant level got low. Our slosh was in the heater core and went away with a new pump and proper fluid level