been looking at buying a a4 2.0 tfsi 2005 off a friend of mine. Trouble is none of the motors that control the airflow to upper ,middle and footwell vents appear to work. The green lever one( windscreen demister moves a little but not much) Have tried all combos on the controls. A mechanic friend of mine has said the problem may be the body control module. Does this sound about right and how much would it be to fix approx.