Hi Patrick,
As you may know the E70 shares a number of same or similar components to its earlier version, the E53.
I know in the E53, warm air out the drivers’ side and cold air out the passenger side is usually a classic symptom of not having enough gas in the air-con.
Mine had this exact problem, and like yours the air-con would work fine when it was cooler; re-gassing it fixed the problem.
The failure message might be a result of, rather than the cause of this problem.
I’m not saying this is your problem but it would certainly be something to consider.