Blower Motor: Description and Operation

The blower motor is controlled by the climate control unit which receives battery voltage at all times through fuse 56. With the ignition switch in ON (II), battery voltage is supplied to the control unit through fuse 7. The control unit is grounded at G404.
Battery voltage is applied through fuse 37 to the blower motor relay contacts at all times. With the ignition switch in ON (II), the blower motor relay is energized and battery voltage is supplied to the blower motor. The power transistor controls the blower motor in all speeds except HIGH. The power transistor is controlled by the control unit. When the control unit requests HIGH blower speed, it grounds the blower motor HIGH relay coil, energizing the relay which connects the blower motor directly to ground, making the blower run at high speed.
When the climate control unit is in the auto mode and requests heat, the blower motor will not turn on until the engine coolant is warm (the radiator fan comes on).