Thanks One pipe is hot the other luke warm, I have also been told that the system could have air in it can it be bled or should it just clear its self and is it something I can do?

Hi I have a 2001 2ltr petrol bongo and although the temp gauge says engine temp is good I get very little heat in the cabin and none in the back area. If I set the mode to face and legs and 32 degrees I get a warmth on fan speed 1 but any higher on the fan and the slight warmth disappears ...