I have a 2002 A4 Quattro. I get heat through the defroster vents but not through the instrument panel vents (they blow cold air). I plan on having the codes pulled today and flushing the heater core tomorrow. However reading some posts I am wondering if I should be concentrating more on the blend doors or similar issues? Any advice would be appreciated.

 

resolved, had some time today and went ahead and did a water flush of the heater core. This resolved it, not a lot of gunk in it but there was air in the system.