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:
1. LOW
2. MEDIUM 1
3. MEDIUM 2
4. MEDIUM 3
5. HIGH

The blower motor will only operate in any switch position other than OFF, as long as the ignition switch is in the RUN position. The blower motor and mode switches are located within the HVAC control module. The blower motor OFF input is connected in series with the HVAC control module by the off blower motor control circuit.

Depending upon the selected speed, power is provided to the blower motor from either the left IP junction block or the right IP junction block. The right IP junction block only provides power when the High blower switch position is selected. Power and ground are provided to the HVAC control module by the ignition 3 voltage and the ground circuits.

Low Blower Speed
When the Low blower speed is selected, the HVAC control module applies voltage to the blower motor resistors through the low blower motor control circuit. Voltage is divided between 4 series resistors, a blower relay, and the blower motor to achieve the desired blower speed. The blower motor is grounded through the ground circuit.

Medium Blower Speeds
When the Medium 1 blower speed is selected, the HVAC control module applies voltage to the blower motor resistors through the medium 1 blower motor control circuit. Voltage is divided between 3 series resistors, a blower relay, and the blower motor to achieve the desired blower speed. The blower motor is grounded through the ground circuit.

When the Medium 2 blower speed is selected, the HVAC control module applies voltage to the blower motor resistors through the medium 2 blower motor control circuit. Voltage is divided between 2 series resistors, a blower relay, and the blower motor to achieve the desired blower speed. The blower motor is grounded through the ground circuit.

When the Medium 3 blower speed is selected, the HVAC control module applies voltage to the blower motor resistors through the medium 3 blower motor control circuit. Voltage is divided between a series resistor, a blower relay, and the blower motor to achieve the desired blower speed. The blower motor is grounded through the ground circuit.

High Blower Speed
When the High blower speed is selected, the HVAC control module applies voltage to the blower motor relay through the high blower motor control circuit. The voltage energizes the blower motor relay, causing the blower motor to be connected to the battery positive voltage circuit. The blower motor and blower motor relay are grounded through the ground circuit.

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 A/C request will be canceled and the A/C request LED will turn off. Fresh air will still be brought in from the outside, but the LED indicator will not illuminate.

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. 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 is selected or the next ignition cycle. Recirculation can be selected with the blower motor in either the ON or OFF position.