I own a 2002 Monte Carlo SS with 3.8 engine.. I was cleaning out my car and had my keys in my pocket. Then about 30 minutes into cleaning, the heater blower turned on for 5 seconds. It blew air out from the floor vents. Then did it again about 30 minutes later for 5 seconds.. What would be causing the blower to turn on by its self when the car is turned off ??