Blower Motor: Description and Operation

CIRCUIT OPERATION
With the ignition switch in RUN and Mode selector switch in any position except OFF, voltage is applied to the coil of the A/C control relay. The relay is grounded always at G200. With the contacts closed, battery voltage is applied through Fuse 20 and the A/C control relay contacts, to the Heater and A/C control assembly and the blower resistors.


Battery voltage at the blower resistors is applied through all three resistors to the blower motor. The blower motor is a variable speed motor which runs at a speed proportional to the applied voltage. The higher the voltage applied to the motor, the faster the speed. With all three resistors in the circuit, the blower runs at low speed to circulate air in the car.

Battery voltage is applied to the blower switch and the contacts of the blower motor relay when the mode selector is in any position except OFF. As long as the blower switch is in the OFF position, the blower will continue to run at the low speed determined by the three blower resistors.

As the blower switch is moved through the LO and MED positions, the switch bypasses some of the blower resistors. This allows more voltage to be applied to the blower motor, which will increase its speed.

When the blower switch is in the HI position, voltage is applied through the WHT/BRN (963) wire to the coil of the blower motor relay. The blower motor relay operates, applying battery voltage directly to the blower motor. The motor runs at maximum (high) speed.