Air Speed - Front Control

The blower motor forces 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 the fuse block on either the ignition 3 voltage or battery positive voltage circuit. 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 decreased across 4 series resistors to achieve the desired blower speed. The blower motor is grounded through the blower motor resistor assembly and ground circuit of the blower motor resistor assembly.

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 decreased across 3 series resistors to achieve the desired blower speed.

The blower motor is grounded through the blower motor resistor assembly and ground circuit of the blower motor resistor assembly.

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 decreased across 2 series resistors to achieve the desired blower speed. The blower motor is grounded through the blower motor resistor assembly and ground circuit of the blower motor resistor assembly.

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 decreased across a resistor to achieve the desired blower speed. The blower motor is grounded through the blower motor resistor assembly and ground circuit of the blower motor resistor assembly.

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 blower motor relay is internal to the blower motor resistor assembly. The voltage energizes the blower motor relay, causing the blower motor to be connected to the battery positive voltage circuit. The blower motor is grounded through the blower motor resistor assembly and ground circuit of the blower motor resistor assembly.

Off Mode
When the OFF position is selected, the HVAC control module applies voltage to the off blower motor control 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 cancelled and the A/C request LED will turn off. Fresh air will still be brought in from the outside.

Recirculation Mode
Recirculation is only available in MAX. When MAX mode is selected, vacuum is applied to the recirculation actuator. The force of the vacuum overcomes the spring pressure of the spring inside the actuator. This moves the actuator, which is linked to the recirculation door, into recirculation mode. This brings air from inside the vehicle instead of fresh air from the outside.