Air Speed - Front Control

The blower motor forces outside air into the vehicle's interior. The vehicle operator determines the blower motor's speed when the driver places the blower switch in one of the following positions:
^ Low
^ M1
^ M2
^ M3
^ High

The blower motor will operate in any switch position other than OFF, as long as the ignition switch is in the RUN position. When the ignition switch is ON, power from the underhood fuse block is delivered to the load side of the blower motor relay through the ignition 3 voltage circuit. Once energized, the load control switch inside the relay connects the HVAC control module to power through the battery positive voltage circuit. The blower motor and mode switches are located within the HVAC control module. The blower motor OFF input is connected in series at the HVAC control module by the off blower motor control circuit.

Power is provided to the blower motor from the instrument panel fuse block. Depending upon selected blower speeds, voltage is either supplied directly to the blower motor or voltage is varied by a series of in-line resistors. Power and ground are provided to the HVAC control module by the battery positive voltage, ignition 3 voltage circuit, ground circuits and splice pack.

Low Blower Speed
When the Low (1) blower speed is selected, the HVAC control module applies voltage to the blower motor resistor assembly through the low blower motor control circuit. Voltage is divided between 4 series resistors, the blower motor resistor assembly relay, and the blower motor to achieve the desired blower speed. The blower motor is included in the series circuit by the blower motor supply voltage and ground circuits. The blower motor resistor assembly provides a ground path for the blower motor.

Medium Blower Speeds
When the Medium 1 (2) blower speed is selected, the HVAC control module applies voltage to the blower motor resistor assembly through the medium 1 blower motor control circuit. Voltage is divided between 3 series resistors, the blower motor resistor assembly relay, and the blower motor to achieve the desired blower speed. The blower motor is included in the series circuit by the blower motor supply voltage and ground circuits. The blower motor resistor assembly provides a ground path for the blower motor.

When the Medium 2 (3) blower speed is selected, the HVAC control module applies voltage to the blower motor resistor assembly through the medium 2 blower motor control circuit. Voltage is divided between 2 series resistors, the blower motor resistor assembly relay, and the blower motor to achieve the desired blower speed. The blower motor is included in the series circuit by the blower motor supply voltage and ground circuits. The blower motor resistor assembly provides a ground path for the blower motor. When the Medium 3 (4) blower speed is selected, the HVAC control module applies voltage to the blower motor resistor assembly through the medium 3 blower motor control circuit. Voltage is divided between a series resistor, the blower motor resistor assembly relay, and the blower motor to achieve the desired blower speed. The blower motor is included in the series circuit by the blower motor supply voltage and ground circuits. The blower motor resistor assembly provides a ground path for the blower motor.

High Blower Speed
When the High (5) blower speed is selected, the HVAC control module applies voltage to the blower motor resistor assembly relay through the high blower motor control circuit. The voltage energizes the relay, causing the blower motor to be connected to the battery positive voltage circuit. The blower motor resistor assembly provides a ground path for the blower motor.

Off Mode
When the OFF position is selected, the HVAC control module applies voltage to the blower switch off input within the HVAC control module through the off blower motor control circuit. When the HVAC control module receives this input, any blower and A/C requests will be cancelled and the A/C request LED will turn off. Fresh air will still be brought from the outside, but the LED indicator will not illuminate. The temperature and mode controls will continue to function only to manipulate the fresh air that enters the vehicle. The recirculation function can still be activated. The recirculation mode will stay on until either fresh air is selected. The HVAC control module will stay in recirculation mode for 30 minutes after the ignition switch has been turned off.

Recirculation Mode
When the recirculation switch is pressed, a solenoid inside the HVAC control module connects the recirculation vacuum actuator to the vacuum source. Power is provided to the recirculation switch by the ignition 3 voltage circuit. Ground is provided by the ground circuit and splice pack. The recirculation actuator retracts, closing the recirculation door. This brings air from inside the vehicle instead of fresh air from the outside.

Recirculation is available in all modes except FRONT DEFROST and MIX-BLEND. The recirculation mode will stay on and the LED will illuminate until either outside air or a non-recirculation mode is selected.

The HVAC control module will stay in recirculation mode for 30 minutes after the ignition switch has been turned off. Recirculation can be selected with the blower motor in either the ON or OFF position.