auto climate conversion to newer version

[ketje01]

Hello, I have a '90TT with the full automatic climate control. I would like to change that to the newer '91-'96 version where I can choose fan-speed and mode. I checked both wiring diagrams and the only thing different I can find is that the later model has an extra relay to switch the climate on when key is switched to "on" instead of the earlier model where the climate come on with key in "acc".
Would this conversion work if just switch both the controlpanel and ecu? Has anybody ever tried this?

Greetings, Mike