04 CAMRY SE 4cyl questions

[RB63]

2 questions I hope for help with.My purchased,new dealer serviced camry has a water slushing sound in the dash ,it seems to be in the center, but its hard to tell. You only hear it sometimes,no real pattern, when engine is running.You can hear it when moving or standing still.I checked ac drain hose and it is dripping ok.I did notice coolant overflow was empty so I filled it to top mark.Could there be air in the system from over flow running dry? Also at my last service I was told 1 of my battery connectors was corroded,it was replaced under warranty. When I looked under the hood to check out the slushing sound,I see my battery terminals, connectors and hold down bracket all have a good bit of corrosion on them. Assuming the repair was done properly the first time,why am I having this problem again or even the first time? I have a 93 camry 200,000 miles and it has no corrosion at all.I have to take it to the dealer soon for regular service and was hoping for some input from the group before hearing what the dealer has to say,which i suspect will be "we dont know and its not covered". Please excuse errors in punct. gram and spelling . Im a talker not a writer. Thanks in advance. RB63

[Gort11]

You probably have an air pocket in the cooling system, your overflow being empty is the cause. Your heater core is in in the lower center of the dash. I think your battery is leaking and causing the problem or is being overcharged by your alternator. If I was you I would take it back to the dealer it is still under warranty. Let them fix it for you.