Sensor broken auto will work for other conditions but won't do anything regarding auc. Auto for example will kick on/off recirculating air to defrost. First recirculating to get more heat then outside to get rid of the moisture.

The sound is very different when recirculating air is enabled. Set the fan to medium high speed and hit the recirc then outside air button.

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2011 E70 • N55 (me)
2012 E70 • N63 (wife)