1. Identify which damper motor you need to replace before you remove the dashboard.
2. Try a software reload and motor calibration to see if you can get the faulty motor moving correctly.
3. If you determine the motor is indeed broken. Know that only the passenger side defroster motor is accessible. The other 4 are behind structural dashboard parts and require removal of the dash as per vida (I can confirm it too).
4. If you do it, be ultra careful when pulling back the dash as the climate box is all plastic and is pinned on the dash, and the main structual beam of the dashboard assemble passes right through its center (the whole climate box is kinda banaba / U-Shaped). So you must lift ever so slightly while pulling the dash toward you. A very tricky move. I DID break both the climate box on the salvage yard car I tried it on, and then damaged the top of my own Climate box on my second attempt.
4. To test the replaced damper motor, you must reassemble the whole dashboard assembly... So you better be sure you had the right one.
Word of advice... Go to the dealer, have the whole unit replaced.
Why?
damper motor: 200$ (there are 5 total)
Climate box: can be negociated for around 1000$ (from 1400 retail price) And it also comes with new carbon filter, new evap core, new AC tubings, no accumulated dusts inside or stuck on blend doors grease, 5 new motors and new blower motor...
Time required to change the damper motor, or the climate box is almost the same... And just changing the motor might not work if the blend door inside the climate box is at fault... So it could require a second attempt where you WOULD have to change the whole unit...
BTW my car was a 2009 C30, did it in 2013.