My 99 A6 Avant runs well, coolant temp rises from start to mid-meter and stops as it should, oil temp is fine, main engine fan runs fine - but - my right-side auxiliary fan will run in what I'd call "emergency" speed when the outside temp is no more than 83 - 85. It sounds very loud, starting up within 2 minutes from engine start at standstill on an 80 deg day. I remember years ago from another Audi where the manual said this was emergency mode and would happen if something else failed, but I don't notice anything failed. As expected in this manual nothing mentioned. Among other owners, is this expected or does it say that I'm on a backup system because something else failed? My Audi guy says it's to be expected, but it sure is an annoying sound, like an airplane running everywhere I stop at a light or parking lot. ?????