With my Omega Caravan 2.5 DTI I had the problem of the foggy disks again and again. Also – and straight! – I had to fight with a lack of visibility in wet-cold weather. An exchange of the interior filter and the control of the processes did not bring a solution. At some point the FOH had to get there. Result: 1. the heater does not work. Was known, however, this was certainly not the riddle solution. Expensive!!! 2. The cooling water thermostat no longer closes. Could have been more of a reason for the evil, as the heating power was rather modest overall. So exchange, also not quite cheap. After that the FOH did not know any more, because the fogging remained. Why I write this now: thanks to this forum I came to the solution: the “hanging” air valve at the cold start was! Since I once briefly switched to circulating air, then again to fresh air, It’s all back in butter, the car doesn’t beat any more. A warm thank you to all the whistleblowers! I would have another question: since the tendency is now to let in cars with green badges in the so-called environmental zones, but my omi only has yellow: does someone know the current price situation for the installation of a soot filter incl. Kat? My car is with just 90000 km on the clock much too bad to throw away, but I have to go into a city now and then. The residual values of these cars are so low that there is no question of selling at acceptable prices.