When running the air conditioner or vent, there is a foul, sour odor that emits from the vents for the first few minutes, especially in hot weather. We had a module replaced by the dealer and it was fine for a short time. The odor is back and they told us there is nothing more they can do except for us to spray Lysol in the vents. We are about to take this issue to GM and Buick headquarters if this is not resolved soon.