The air delivery controls are divided into two primary areas. The first, air speed, is dependent upon blower motor speed. The second, air distribution, is related to various single or multiple air outlets.
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 |
| • | Medium 1 |
| • | Medium 2 |
| • | 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 instrument panel fuse block is delivered to the blower relay. The coil is energized and closes the switch in the relay and power is sent to the blower motor. The blower motor is supplied constant power any time the ignition switch is in the ON position.
Ground is provided to the blower motor from HVAC control module depending upon selected blower speeds, ground is either supplied directly to the blower motor or ground current is varied by a series of in-line resistors. Power and ground are provided to the HVAC control assembly by the ignition 3 voltage circuit, ground circuits.
Low Blower Speed
When the Low blower speed is selected, the HVAC control module applies ground to the blower motor resistor assembly through the low blower motor control circuit. Current is divided between 4 series resistors in the blower motor resistor assembly. The blower motor is included in the series circuit by the blower motor supply voltage circuit.
Medium Blower Speeds
When the Medium 1 blower speed is selected, the HVAC control module applies ground to the blower motor resistor assembly through medium 1 blower motor control circuit. Current is divided between 2 series resistors in the blower motor resistor assembly, to the blower motor to achieve the desired blower speed. The blower motor is included in the series circuit by the blower motor supply voltage circuit.
When the Medium 2 blower speed is selected, the HVAC control module applies ground to the blower motor resistor assembly through medium 2 blower motor control circuit. Current is divided by a single resistor in the blower motor resistor assembly, to the blower motor to achieve the desired blower speed. The blower motor is included in the series circuit by the blower motor supply voltage circuit.
High Blower Speed
When the High blower speed is selected, the HVAC control module applies ground directly to the blower motor through the high blower motor control circuit. The blower motor voltage supply circuit provides complete path for the blower motor.
Off Mode
The blower motor and A/C compressor are turned off. When the vehicle is moving, air flowing over the vehicle increases the air pressure just ahead of the windshield. This forces air into the outside air inlet, into the HVAC assembly and out through the defrost outlets. Since the A/C compressor is not running, the incoming air may be warmed but not cooled.
Recirculation Mode
When the recirculation switch is pressed, a signal is sent from the HVAC control module to the recirculation actuator through the recirculation door control circuits. When the recirculation actuator receives the signal, the actuator moves into the recirculation mode. This recirculates air inside of the vehicle instead bringing fresh air from the outside. Power is provided from the instrument panel fuse block, through the blower relay to the recirculation actuator. The HVAC control module monitors the position of the recirculation door from a signal sent over the recirculation door signal circuit. Recirculation is available in any mode.
Air Distribution
When you select different modes, a signal is sent through the mode door position signal circuits (A through F) to the HVAC control module telling the module what position the door is in. The module then applies voltage and ground to the mode door control circuits switching the polarity, depending on the direction the door needs to move to acquire that specific mode that the operator selected.
Vent Mode
When VENT is selected, air is delivered through the instrument panel outlets with a small amount of air delivered to the floor.
Bi-Level Mode
When BI-LEVEL is selected, air is delivered through the instrument panel outlets and the floor outlets.
Floor Mode
When FLOOR is selected, most of the air is delivered to the floor outlets and the rest of the air is routed to the windshield outlets.
Mix-Blend Mode
When MIX-BLEND is selected, air is delivered to the windshield outlets and the floor outlets.
Defrost Mode
When DEFROST is selected, air is delivered to the windshield outlets.
