An automotive heater is used to supply warmth to the passengers of the vehicle. Conventionally this has been done using the coolant heated from the engine and then run through the heater core via the heater hoses. For electric motor vehicles this is achieved by heating a set of resistance wires (much like a bread toaster) using the main battery and then allowing a blower fan to push the heated air through the vents. Heater system controls are adjusted by one of two ways, either a manual system is used which is adjusted by the driver or a climate control computer responds to a setting which is then automatically adjusted. Some manufactures have separated the heater system into passenger and drivers side controls which offer independent temperature adjustments. Many aspects of the heater system can malfunction such as an engine coolant leak can develop which hinders the performance of the heater system, these leaks must be repaired before proper heater operation will return.