It's hard to describe. Like a sick bird or a dog squeaky toy, but not as loud. It's random, happens no matter how I'm driving (or not driving), can be quiet for 10 min or more, then suddenly start. Happens whether the vent/heat/AC is on or not. Even when the car is off.
I thought it was something w/the engine at first and my coolant and brake fluid were low so fixed that, and checked for animals in it--none. But the noise is more in the vent area.

Not sure what to do. Should I take it in?