My problem is that the main vent of my 850 is only running in the max. position. Between min. and max. position of the middle dial there’s no ventilation. From time to time it works when the middle dial is switched to max. position for some minutes and then moved back. When it works all looks fine and the vent speed could be controled. The next day it is off again. Which part could be damaged and where is it located? I thought of looking at the conectors of the climate control unit, but can’t guess how to get it out. Any help? (Sorry for my broken english.)