Where do you start to get behind the aircon control panel on a VS?
Vacuum hiss behind there, no air on the face position.
Not a mechanic, can I do it?
You will have to remove the radio surround to get at it,there are 2 screws under the radio somewhere. You should be able to locate and fix the problem yourself. Just find where the hiss is coming from. Probably one of the many hoses back there.