I got curious about this, so I fooled around in my climate settings. I found that if I adjusted the horizontal bar down, such that it was blue or multiple blue bars, the AC activated on its own. I'm sure this is a really ****ty explanation, but the settings to fix your problem are in that section. Hold the iDrive knob to the left for ~3seconds, then push towards the rear to move down the sections and then to the right once to get to this horizontal bar. The bar should be white. It turns blue if you want it colder and red if you want it warmer. I figure it turns the heat on if it's red. If you're still having trouble, I'll go take some pics after lunch.