Albert, sorry spent 6 months getting to the problem so got lost in the termology! It's the black box located under the passenger side dash with the large hoses that go up to the dash air vents and defrosters. The box two pieces fastened together on each side of the firewall. It contains a ac coil and a heater coil where it blends the two airs together for what ever temp you set using the controls. Ours was not fastened flat against both sides of the firewall so it leaked both inside air and outside air, the ac would only make 6 degrees at best when it was 80 degrees outside, the heater worked good enough to defrost the window. Anyways once that was repaired we noticed all wind noise had stopped and DW no air movement from under the dash. You probably don't have this problem as I was told it was a production fluke. If if your chassis AC works just fine then this doesn't apply to you. Those weep holes made a huge difference in noise. Hope this helps!!
2015 FR3 25DS
2014 Fiat 500 Sport The Toad