The blower motor forces air through the vents. You are able to control the speed of the motor through switches, buttons, and dials on the dashboard. The motor contains a resistor which allows it to change the speed of the fan. Without this part you will not be able to change the speed of the airflow from the blower motor. Without a functioning blower motor a vehicles engine runs the risk of overheating. If the blower motor isn’t running the driver should use a voltmeter to check for a blown fuse, if you find one you should replace it. Electrical Motor and Fan Older models may or may not have a resistor, if yours does please specify Switches or controls An electrical motor and fan that blow air for the a/c-heating system. MAY OR MAY NOT HAVE RESISTOR WITH THIS--ASK YARD.