What was found
DURING ROUTINE OIL CHANGE, FOUND MAGNETIC LATCH FOR ALTERNATE AIR DOOR BOX VERY WORN AND AREA AROUND IT COVERED IN ALUMINUM DUST. THE LATCH HOLDS THE DOOR IN THE CLOSED POSITION UNTIL THE AIR FILTER BECOMES CLOGGED WITH WATER/ICE (WHEN IN SUCH CONDITIONS) FORCING THE ALTERNATE AIR DOOR TO OPEN AUTOMATICALLY. WE ROUTINELY FIND THESE LATCHES VERY WORN AND ON THE VERGE OF COMING APART. THIS AIR BOX/LATCH SETUP IS USED ON SEVERAL MODELS, WHICH ALL HAVE THE SAME RECURRING WEAR PROBLEM.