Yesterday I replaced my old climatronic controls with the ECON button
to a mint condition newer version with the AC button
which I thought should be a direct swap. Now I understand the reversed functionality of the ECON and AC buttons, but turning my AC button on seems to disable the aircon completely to the point where it doesn't blow any air out of the vents, it justs makes a whole heap of noise behind the dash. When I turn the AC button off again I get a rush of cold air out and then it blows normally. I did verify with VCDS that pressing the AC button activates the compressor and there are no faults logged.
I'm very confused why this is happening, is there some sort of wiring change needed between the two panels or is the car somehow programmed to handle the button differently (surely the climatronic panel handles this but)? Anyway I'll be swapping back to my old panel if I can't get the new one working normally.