I cannot get the distribution control knob to the defrost position on my 2003 TD4. It springs back slightly when I try to obtain demist/defrost position and there is little hot air coming out of the windscreen vents. It appears there is still a large proportion of heat being deflected to the floor area. This is a bit frustrating when trying to defrost on a frosty morning after running the engine for 10 or so minutes to get a bit of heat into the coolant system.