Just bought 95 960 - love it. Strange though there is a hissing noise that's pretty consistant (stops now and then only to begin again a few seconds later) located near or in the passenger side vent underneath or at the base of the dash (like in back of the center console kinda). I can put my hand over the vent thing down there and sound becomes muffled. Any ideas?

My only guess would be that one of the vacuum hoses for controlling the parts of the heater/a.c. unit are hanging loose. I dont know anything about your volvo, but the hissing on any car is likely the same thing - a small vacuum leak.

Sounds like a vac. leak.