I actually have this same problem with the OEM knob climatronic unit. I did the retrofit over the winter and noticed when it was cold out that my windows would fog up and the defogger didn't really do anything (because the A/C wasn't running).This is more for the people who have done this retrofit with the capacitive climatronic unit from the Chinese market. Has anybody noticed issues with their A/C not working, despite the car saying it's on? My A/C button will light up, and if I go into the menu on the infotainment, it says the A/C is on. But since it has been cold, I didn't notice that the condenser wasn't actually kicking on, and the air wasn't actually being chilled until the other day. I took the unit out, put it in my buddy's Autobahn, did the compressor run in, etc... and it works fine in his car. A\C turns on and blows ice cold. Put it back in my car, and nothing. The interesting thing is, if I put his knob-based climatronic unit in my car, A\C works fine.
When I initially got the capacitive unit, I messed a bunch of stuff up with it trying to fix an issue that couldn't be fixed, but thought I had corrected everything. So I don't know if it was something I did, or just the way it is. But it's strange it'll turn on the A\C in his car, but not in mine .
I tested in my driveway putting max A/C on, and looked in the engine bay and confirmed the compressor wasn't running. In OBDeleven, in the climate module, it said (I don't remember the exact wording) the A/C compressor status was function limited due to low temperature. Apparently there is some outdoor temperature limit where the climate unit will not kick on the compressor. I have not found out a solution to this problem yet, and in the meantime have swapped back to the manual control unit as the fog on my windows was a hazard driving in the colder winter months.