I have what seems a common problem in that I can't get any hot air through the vents. I'm aware that the center vents are only cold, but it won't blow hot through the side or screen vents either. It seems that the heater control cable is not connected (heater valve doesn't move under bonnet when knob turned), but I have adjusted the valve by hand, and that hasnt made any difference either - Only had the van a week so assuming this may not have been working for some while. Any ideas? All are welcome ?