When I start my car after its been sitting for a few hours, I hear a sound like water slushing around coming from the area ranging from my Radio/AC controls down to my automatic gear selector. I brought the car in for service and the techs thought it was air in the coolant line so they did a flush of the lines, but when I picked my car up it still had the sound. Is there still air in the line or could it be some other problem? I'm brining the car back today I just wanted to hear what you guys think.

 

*bump*

 

I have this sound all the time, I never thought anything about it. But only after a long time of sitting (like over night or a couple of days).