I don't think you can just switch...
This is the first time I will have pulled a dash on a mk4 but I have done a couple of heater cores on mk3s before so I do know whats involved in pulling a dash out (not hard but frustrating and slow).
I'm doing work. (Build Thread) | VCDS Scans / Tweaks in the Waukesha / Milwaukee area for $5 or a 12-pk of Mountain Dew | MK4 Remote Window Control for $20
Yeah I thought I remembered that had to be done, luckily I want to change my coolant anyway (idk how old it is) and my a/c works but with a black car I want it to be ICE cold.Also, the AC does need to be discharged and the coolant does need to be drained.