Air Delivery

The Air Delivery description and operation is divided into 3 areas:
- HVAC Control Components
- Air Speed
- Air Distribution

HVAC Control Components

HVAC Control Module




The HVAC control module 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. Three integrated potentiometers control air temperature door position and blower motor speed. The integrated vacuum system controls the mode door position. The control assembly supports the features as in the table.

Air Speed
The HVAC control module 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-4 resistors
- Medium 1 speed-3 resistors
- Medium 2 speed-2 resistors
- Medium 3 speed-1 resistor

When the operator requests High speed, 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, connecting the blower motor to battery positive voltage.

Air Distribution

Vent Mode
When the operator selects VENT, the A/C Bi-level mode actuator has vacuum applied to it through the Blue vacuum line, making the vent door open. The heater/defroster 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 A/C Bi-level mode actuator is in neutral position.
- The heater/defroster actuator has vacuum applied to it through the Red vacuum line.
- The heater/defroster actuator closes the defrost door, thus opening the heater door though 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 A/C Bi-level mode actuator has vacuum applied to it through the Brown vacuum line, pushing the vent door closed.
The heater/defroster 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 A/C Bi-level mode actuator has vacuum applied to it through the Brown vacuum line, pushing the vent door closed.
- Vacuum is bled off the heater/defroster 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.

Defrost Mode
When the operator selects Defrost, the following occurs:
- The A/C Bi-level mode actuator has vacuum applied to it through the Brown vacuum line, pushing the vent door closed.
- The heater/defroster 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.