Have a 2011 Terrain. Twice now when I have changed the cabin air filter I've found the remains of acorns on top of the air filter. The filter fits the housing very tight and as I remove the filer to change it, the acorn remains fall into the blower motor. Now I have to remove the blower motor to get the acorns out or they cause an imbalance in the fan and the dash vibrates. I can't figure out where they are getting into the air duct system. Anyone ever have this problem and found out where the rodents are getting in?