Hey, I have an Audi B7 3.0 TDi V6 (240bhp model) and im banging my head against a wall with my cooling system. For weeks and weeks it was heating up to temperature as normal but would then fluctuate between 70 and 90 degrees, but never once overheated. The blowers inside the car only blow freezing cold air. The car overheated one day just ever so slightly and the fan came on. I thought the issue was likely to be the thermostat so I had it replaced which had no effect. Now its the same but it is doing the slight overheating more often, fan kicks in, it comes back to temp and runs fine for the next half hour, then it comes on again. Its only going a needles width above the 90. during this whole thing I noticed that when at temperature, you can take the lid off the overhead tank and dip your finger in comfortably, though there is pressure in the bottle. So it doesn't seem to be circulating. I thought the fact there is pressure in the bottle, meant it couldn't be the headgasket. I thought the fact that its going under temperature that it wouldn't be the water pump as it would be more frequent. Does anyone have any idea what this could be? I thought maybe the temp sensor but then I didn't think that would cause it to blow out cold air inside the car? Any help would be amazing as I am sick of this now. Thanks, Kevin.