Have posted before but its getting difficult.
History is bought car 3 years ago at under 7,000miles. Now on 21,000. Has Auto Aircon - Climate control
The left side of the ventilation system is always cold.
(Right side works normally through the temperature range) so if heating high I get heat on Right side but cold on left.
Note in diagram there does not appear to be a Left Right split for the airflow with each contral vane being one piece for both halves.
Airflow Direction control
Air comes out of all vents dependant on setting eg windscreen, footwell central and side vents which confirms Directional Flap control is working as it should. I have had radio out and top centre dash panel and can see the motor and levers cycling when direction of airflow is changed.
I have drained, flushed and refilled coolant suspecting an air lock in the left side of the heater matrix. Despite several attempts at bleeding/purging air there is no change to the problem.
Picture shows Dash with air as arrows. and schematic.
Short of completely removing the Dashboard and HVAC components I am a loss what else it could be.