I have similar stochastic problems. It sometimes works and sometimes doesn't; it may start okay, but after a few hours, it begins blowing cold without any adjustment or change in the outside temperature.
If I set the climate control to auto mode at 20-22 degrees, ice-cold air frequently enters the passenger footwell (I believe it's the recirculation duct under the glove compartment). It's getting too cold to sit in the passenger seat. At the same time, very warm air usually flows through the vents in the back seat, which might be 10-20 degrees warmer than the front.
The automatic system never provides warm air to the windscreen defroster, thus fog and/or ice accumulates on the windscreen in cold weather until you manually manage the airflow.
It also appears that there is no method to distribute warm air to the feet, panel vents, and defroster all at once, which is preferable when it's freezing outdoors.
In summary I've probably never encountered an automatic system that operated so poorly, which is quite an accomplishment given that I previously owned a Citroen CX and several Land Rovers. Operating the system manually does not appear to be a solution because it frequently ignores the settings that are made.