No heat drivers side

2014 A4 B8. No heat on drivers side but have AC. Heat and AC on passengers side- all good there.

I've scanned with VDCS no faults recorded on HVAC ECU. I can actuate all the HVAC motors, no problems reported and can hear eat actuator/motor working. I've done the relearn process for the HVAC motors still no joy. When I turn down temp on drivers side I get cold air then change to HI heat, it goes from cold air to ambient air. I think my problem is associated with the linkage/doors associated with V159 right side temp control. It looks like a nasty job to get that motor out. and get access to linkages etc. I think I may have to take the steering column and pedals out. Anyone with any experience of this problem/symptom. Don't want to get all that out and its nothing to do with V159 and linkages etc... Any help or ideas appreciated. Thanks.