Orifice tube and expansion valve location

Hardly ever just means you might be the "lucky" owner.

I would use a scan tool and test the actuators. I highly doubt it's any of the cores, if they were blocked the issue wouldn't go away.

Without a scan tool to test you could replace every part of the system and still not have it work. Sorry but that is a fact. At the moment it could be the temperature control doors, the fresh air door, the body control module, the temperature sensors or the main control head. The BCM and HVAC controller both are units that have to be programmed, The actuators also need a scan tool to reset them to the base positions if they are replaced.

There are a few that cover the VW/Audi Group vehicles, but those cars can be touchy when it comes to what works and what doesn't. There are a lot that can read the codes but many cannot read the odd VW long codes or connect to all the modules. About the best aftermarket unit is from Ross Tech.