The airflow for the HV battery is filtered by a serviceable air filter that is similar in design to an A/C cabin filter. As the hybrid system charges and discharges the high voltage hybrid battery pack, large amounts of heat are created. In order to dissipate this heat, cooled and filtered air is drawn over the battery pack that is provided by the vehicle's A/C system. There is an automatic door that meters the amount of cooled air flow to the battery pack depending on its temperature reading. This means that the vehicle's A/C system runs when ever the battery pack needs cooling but only cools the passenger compartment when the occupants request it. These filters are typically replaced every 10,000 miles or once a year depending upon which interval occurs more frequently.