Blower Motor: Description and Operation

The Blower Motor circuit employs the following components:

Blower Motor
Blower Resistor Assembly
Blower Switch
High Blower Relay
Mode Selector

With the Ignition Switch in "RUN," battery voltage is applied to the Mode Selector. The Mode Selector funnels power to the Blower Switch in all modes but "OFF." With the Blower Switch set to "LO," battery voltage is applied to the Blower Motor though the Blower Resistor Assembly and the normally closed contacts of the High Blower Relay. The Blower Motor runs at low speed. When the Blower Switch is in the "M1" or "M2" positions, the operation is similar to the operation in "LO" except the resistance through the Blower Resistor Assembly is decreased, causing the Blower Motor to run faster in "M1" and even faster in "M2." When "HI" blower speed is selected, the Blower Switch applies voltage to the High Blower Relay coil. The High Blower Relay is energized, applying voltage from CKT 2 through the relay directly to the Blower Motor. The Blower Motor then runs at high speed.