Thanks for the quick response.
Using a Bavarian Autosport fault code reader, I checked for fault codes. There are none. I haven't been to the dealer. My experience is that when it isn't 'broke' they can't fix it.
Is there a single failure (intermittent or other) that you can think of that would cause this problem? Actuator? Cabin temp sensor? Cable? Other?
When last happened, selecting AUTO, MAX, lower, mid or upper had no effect on air distribtuion. Only control that had any response was manual fan speed: you could hear fan speed up / slow down. Can't remember what happened when I hit defrost button, but I don't think the airflow changed (could be mistaken).
Will be driving a shorter distance today! If it happens, I'll try to get more data.
Saturday, May 30th, 2009 AT 6:13 AM