Shifting Sand Sound (or hiss) when turning left with AC on

2009 Mitsu Galant here,

So I have the issue similar to this one here :

http://community.cartalk.com/discuss...-i-make-a-turn

Essentially, only when the AC/Heater is on - and I turn left. There is a strange sliding, sound going on coming from around the glovebox area. It sounds like a hiss or sand sliding. Also, if I come to a complete stop to fast it sounds like water sloshing over in the same area. I never knew this sounds because I've always had the radio turned up. I recently installed amp wiring and went through the firewall on the driver side so I doubt that could cause any issues. I went through the little knockout area where generally the clutch would come through. I've installed thousands of amp wires and never have caused any issues (former car audio installer) so I'm doubtful that was it.

Any idea what this could be? Anyone had the same issue?

You probably have an air bubble in your heater core.