I have not had any AC issues in the X5, but I remember reading about the red and blue stuff, and if you had an E53, you remember that the dials on top of the vent do the same thing. It either makes the air slightly colder or warmer. So the HVAC in the X5 works excellent, even with the rear climate on 100% of the time. I haven't found that an issue.
But in the X3, it feels like all the cold air is escaping. It never gets comfortable in there
Glad you got yours fixed x5fx