The center and rear dash sections removed. The entire dash does not need to come out. Simply remove the center consoles, the driver side lower panel, and the glovebox. This will expose the ducts that need to be seperated from the airbox.
You may notice leaves all over the passenger side carpet. These came from the recirculation flap located above glovebox. Now is a great time to clean it out. Open the flap by hand and clean out any debris. Mine was clogged full of leaves and kleenex.
Testing position/temp flaps with VAG-Com.*
Disconnect the left/right footwell vents as well as the rubber center section from the airbox:
Driver side footwell duct... these just snap out:
Heater box out after all hoses disconnected. I used a few broom sticks to pry the box out.
Where the heater core lives:
Heater core inlet/outlet. I suspect this is where the leak was happening. Peel away the factory sealent with a screwdriver.
Airbox seperated, blower motor out. I should really replace the blower motor now, but I don't have one on hand. It's a good time to clean up and re-lube the rubber blower motor mounts, as well as cleaning up any dust and dirt.
Heater core removed:
For re-assembly, purchase a new airbox seal, part number 431 819 225. Should be around $10. For reference, the heater core part number is 443 819 030. RTV silicone can be used to reseal the heater core into the box.
*All temp/position flaps use the same servo motors. Worlpac sites only list one flap motor, but it can be adapted for use in all temp/position applications. Make sure the red/blue motors connected to the heater box are fully operational before re-assembly. Pulling the fault codes from the climate control will help diagnose any problems.