I have a 2004 Impala and I hear water sloshing.
It sounds like it is coming from the passenger side under dash or quarter panel.
Is there a drain some where? If so where?

Thanks
Tim C.

 

Sounds like air in your cooling system and sloshing is in heater coil..or it could be those damn frogs again.

 

Open your hood and go near the cabin filter. Remove the top plastic over the filter and you will see a rubber molding that fits tight in a groove. This molding prevent the rain water to get in the passager compartment. You will certainly notice that the molding has come off the holding groove. No need to buy a new one just use silicone and replace it in the groove slot. Then your problem will be solved. No more flooding on the carpet.

 

Make sure your coolant reservoir level is staying at the same level. If it is dropping you might have a coolant leak at the heater core. Which is on the passenger side and sloshing around in the heater core housing. Make sure your flooring is not wet and smells like coolant. Some heater core housings will not drain completely and "sloshing" can be heard. The fix is replacing the heater core.