Hi, I am driving a 2002 E39 520. The air con is working perfectly. However, I experience hot air coming out of rear vents after driving car for a period of time. I noticed that the centre part of the car below the dashboard gets pretty hot. Subsequently, if I start my car after I parked, gear-box jerks very badly when it changes gear. This usually goes away once the car is sufficiently cooled down after a drive. Does anyone have any idea what is happening here? Performance SA asked me to turn the air con colder to cool down the hot air from the rear vent.