After a heavy rain storm, the drains for the heating, ventilation and AC (HVAC) system intake can be plugged with leaves and other debris, causing a dead battery. Water fills the intake cavity and overflows into the vehicle, directly onto the blower motor and its regulator. This causes the regulator to short out and the blower motor will continue to run, despite the key being off and removed from the vehicle. Usually the carpet at the right front passenger floor will be wet too. If the carpet is saturated, the passenger seat may need to be removed to dry out the battery storage area before water or moisture reaches the relay and fuse holders. To prevent this, do not let leaves and twigs accumulate at base of windshield. If there are leaves or debris below the wiper blades, clean the area.
Plugged drains in HVAC system intake may cause dead battery on Mercedes-Benz ML63 AMG
Average mileage: 45,000 (45,000–45,000)
5 people reported this problem