I know very little about air conditioning systems, so here goes. Car is a 2003 1.9 TDI B6 A4 with the standard 2 zone climate control. It's had a problem for over a year now really. On moderate days (15-20 degress) after sitting for a day in the sun, I get in and open the windows to let the hot air out. I turn on air con to 21 and leave it. Fan speed will go to 1 or 2 bars and stay there for about 3min, pumping out cool air. Then after that the fan speed goes to 4-6 and pumps out cool (not cold) air. So all is fine, despite it not doing what it should. On a hotter day, or if I put the air con on LO, the fans go crazy and just pump out ambient air. So that's the problem. It was recharged a year ago (professionally) and there are no fault codes stored. Does anyone have any ideas what the problem is? It strikes me as a problem with wear somewhere in the system - because it works when running at low speed, but not faster. Any ideas gratefully received!