there are 2 things behind dashboard that can make a wind like noise. First is the economy gauge in the instrument cluster. It uses vacume and if the rubber hose connection behind the cluster is off, you will hear a noise and the economy gauge will not work. The second source is the headlight adjustor nearby headlight switch. The rubber house split thing located behind the brake booster supplies the vacume to economy gauge and a headlight adjuster.
My car's heating system buttons don't use vacume but yours may.
Hope this will help.
1989 230E, 8v, 166.000 km, updated to 94/95 trunk & hood
2002 Daewoo Nexia 50.000 km
1987 VW Jetta GLE 16V, Recaro seats
1982 Volvo 240 DL (lovely car!)
and few more american cars.