Hello, I’m a new employee at a company and drive an old atego. He has the tachodisk still front to open under the tacho. I drove the whole week always 400 km per day. Today when I was on the return trip the on the highway began to whistle quietly. At the front of any place. Then almost on the company when unloading in the stand whistles quite loud. That wasn’t the whole week!! Driving he does normal. Or I don’t know if it’s more a howling. On the company there was no one there because I s Later came back today. Otherwise I would have asked someone there. I have no idea of such a thing. It comes somewhere under the hood I think. Does anyone know a advice?