Blower Motor
The Blower Motor controls supply ground to the motor through the following
components:
| • | The Blower Speed Switch contacts |
Circuit Breaker #6 can supply battery voltage to the Blower Relay Coil
when the ignition switch is in the RUN position through the BRN (198) wire.
Circuit Breaker #24 provides relay contact power for the operation of
the Blower Motor. The relay contact power is provided when the ignition is
in the RUN position.
Motor speed is controlled by routing the blower motor ground through
dropping resistors.
The Blower Motor Speed Switch supplies ground through one of the resistors
for all of the speeds but HIGH.
The following conditions exist when the Blower Motor Switch is the LO
position:
| • | Voltage is applied from the switch contacts through the BLU/WHT
(180,196) wire to the Blower Motor Resistor. |
| • | The Blower Motor current flows through all three resistors. |
| • | Grounding is provided through the following components: |
| - | The switch common terminal |
| - | The HVAC controller module |
| • | Current flow is established. |
| • | The Blower Motor operates. |
| • | The voltage drops through the three resistors in the Blower Motor
Resistor. |
| | The drop in voltage limits motor operation to the lowest possible speed. |
The following conditions exist when the Blower Motor Switch is in the
MED LO position:
| • | Voltage is applied to the Blower Motor Resistor through the BLU/BLK
(181/195) wire. |
| • | Current flows through two resistors in order to get to the motor. |
| • | The motor operates at a faster speed than through all three resistors. |
The following conditions occur when the Blower Motor Switch is in the
MED HI position:
| • | Voltage is applied to the Blower Motor Resistor through the BLU/YEL
(182/194) wire. |
| • | Current flows through only one resistor in order to get to the
motor. |
| • | The increased voltage causes the motor to operate at a faster
rate. |
The following conditions exist when the Blower Motor Switch is in the
HI position:
| • | Voltage is applied directly to the Blower Motor through the BLU/RED
(183/192) wire. |
| • | Current flows directly to the motor. |
| • | Maximum voltage is applied to the motor. The motor operates at
the fastest possible speed. |
HVAC Temperature Actuator
The HVAC Temperature Actuator controls the amount of engine coolant
that is available to the heater core. The operator heat selection lever position
is translated into an electrical signal.
The Temperature Actuator controls a motor operated valve in the engine
coolant line. The position of the valve is changed in response to the operator
temperature selection. The valve is driven open in order to provide more
heat energy. The valve is driven closed for less heat.
