This is my second 6 (the latest version) and notice the aircon works a little differently to my previous car (2002). When the large knob marked auto is pressed the A/C starts. If I adjust the temperature downward, the fan stays at a constant speed until I drop the temp to about 15degC when it speeds up instantly. On my previous car the fan speed ramped up as the temp was dropped. Is this how the A/C should function on the latest models, or do I have a fault?