Volvo Repair: Resonance above 100 km/hour, volvo 240, air dam

Question
My car makes a resonance noise in the front of the car when I exceed the speed of 100 -120 km/h dependend on wind speed.

Do you know what it is and where it comes from and above all what to do.

My car is a Volvo 240 Polar U9 build in 1992

Answer
Hello,
      Many parts of body may cause noise you speak of.
       Sunroof partially open ....misc.body panels including...lower engine cover...sits under motor..air dam located under front bumper...antennas or other placed items can make a resonance like noise   .
            Good luck,
                        Bilbo

     Whats a U 9?