The air delivery description and operation is divided into 4 areas:
| • | HVAC Control Components |
| • | Air Speed |
| • | Air Distribution |
| • | Recirculation Operation |
HVAC Control Components
HVAC Control Assembly
The HVAC control assembly is a non-class 2 device that interfaces between the operator and the HVAC system to maintain air temperature and distribution settings. The battery positive and ignition 3 voltage circuits provide power to the control assembly. Two integrated potentiometers control air temperature door position and blower motor speed. The integrated vacuum system controls the mode, recirculation, and defrost door positions. The control assembly supports the following features:
Feature | Availability |
|---|---|
Afterblow | No |
Purge | No |
Personalization | No |
Actuator Calibration | No |
Air Speed
The HVAC control assembly applies voltage to the blower motor control circuit that corresponds to the selected blower speed. The resistors and the blower motor are in a series circuit. The following list represents the number of resistors in series with the blower motor per particular speed request:
| • | Low speed-3 resistors |
| • | Medium 1 speed-2 resistors |
| • | Medium 2 speed-1 resistors |
When the operator requests High speed, the HVAC control assembly applies voltage to the blower motor relay through the high blower motor control circuit. The voltage energizes the blower motor relay, connecting the blower motor to battery positive voltage.
Air Distribution
Mode Switch
The mode switch is a rotary vacuum valve that directly applies vacuum to the appropriate vacuum actuator. Use the mode switch to change the air delivery mode in the vehicle.
Vent Mode
When the operator selects VENT, the mode actuator has vacuum applied to it through the Blue vacuum line, making the vent door open. The defrost actuator has vacuum applied to it through the Red vacuum line, making the defrost door close and the heater door open through mechanical linkage.
Bi-Level Mode
When the operator selects Bi-Level, the following occurs:
| • | The mode actuator is in neutral position. |
| • | The defrost actuator has vacuum applied to it through the Red vacuum line. |
| • | The defrost actuator closes the defrost door, thus opening the heater door though a mechanical linkage. |
| • | Vacuum is bled off the mode actuator and the vent door is held stationary in the half open position. |
Floor Mode
When the operator selects FLOOR, the mode actuator has vacuum applied to it through the Green vacuum line, pushing the vent door closed. The defrost actuator has vacuum applied to it through the Red vacuum line, pulling the defrost door closed and opening the heater door through mechanical linkage.
Mix-Blend Mode
When the operator selects Mix-Blend, the following occurs:
| • | The mode actuator has vacuum applied to it through the Green vacuum line, pushing the vent door closed. |
| • | Vacuum is bled off the defrost actuator, holding the defrost door stationary in the half-open position. The heater door is also held stationary in the half-open position through mechanical linkage. |
| • | A/C is forced ON. |
| • | Recirculation is not available. |
Defrost Mode
When the operator selects Defrost, the following occurs:
| • | The mode actuator has vacuum applied to it through the Green vacuum line, pushing the vent door closed. |
| • | The defrost actuator has vacuum applied to it through the Yellow vacuum line, pushing the defrost door open and closing the heater door through mechanical linkage. |
| • | A/C is forced ON. |
| • | Recirculation is not available. |
Recirculation Operation
When the operator selects Recirculation, a solenoid inside the HVAC control assembly connects the recirculation door vacuum actuator to the vacuum source. The recirculation actuator retracts, closing the recirculation door. A/C is forced ON. The recirculation operation can function with blower motor in either the ON or OFF position. Recirculation is not available in Defrost and Mix-Blend mode.
