Started happening a few weeks ago. I noticed that after it rains considerably, I hear water sloshing around, right behind the dashboard. I take it water is pooling somewhere against the firewall. After a few hard right and left hand turns, the sound stops, so I guess it is draining (not inside the car, thankfully). Anyone else have this happen?

 

Open the hood and look on the driver's side where the wiper motor is located. On the driver's side, there is a screen that you can look into and see. There is an area where water can pool up if the drain at the bottom comes clogged with small debris. You need to unclog it. The wiper arms and cover need to be removed to access it.

 

I will take a look...thanks!

 

Inside the dash? Could be the heater core (low coolant - air sloshing around in the core).
(Older cars - I have not had this problem on my HHR though).

 

look in your front wheel well behind the tire. there are vents on each side to let water drain out of the cavity where your wiper motor is (what 87 silver is talking about) . they could be plugged. they have a soft rubber flap on the back side you can lift to see if its plugged. mine drain pretty easy cause they got smashed the first time i layed the fron out.