I have a 52 plate Audi A4 convertible 2.5tdi with dual aircon/climate control. It has always worked fine up until today. I was taking photos to put it up for sale so had the roof up, then down, then up etc. On the way home from taking the photos, I was a little cold so turned up my side of the heater to HI, but it was blowing out cold air. I have played around with the temperature, used aircon and econ, but it remains cold. The passenger side changes as it should, but not the drivers side. Can anyone suggest what might be wrong with it and whether I'm looking at mega bucks or if its a cheap fix? I hope its a common problem and a cheap fix as I'm selling the car due to needing money Any help is much appreciated.