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 device that interfaces between the operator and the HVAC system to maintain air temperature and distribution settings. An ignition 3 voltage circuit provides power to the control assembly. The mode, air temperature and recirculation actuators are electrically controlled. The control assembly does not support the following features:
Feature | Availability |
|---|---|
Afterblow | No |
Purge | No |
Personalization | No |
Actuator Calibration | No |
Air Speed
The HVAC control assembly applies a 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 direct voltage to the blower motor.
Air Distribution
The mode actuator is a 5-wire bi-directional electric motor that incorporates a feedback potentiometer. Low reference, 8-volt reference, position signal, and 2 control circuits enable the actuator to operate. The control circuits use either a 0 or 12-volt value to coordinate the actuator movement. When the actuator is at rest, both control circuits have a value of 0 volts. In order to move the actuator, the HVAC control module grounds one of the control circuits while providing the other with 12 volts. The HVAC control module reverses the polarity of the control circuits to move the actuator in the opposite direction. When the actuator shaft rotates, the potentiometers adjustable contact changes the door position signal between 0-8 volts. The HVAC control module uses this value to index the actuator position. When the module sets a commanded, or targeted value, one of the control circuits is grounded. As the actuator shaft rotates the changing position signal is sent to the module. Once the position signal and the commanded value are the same, the module removes power and ground from the control circuits.
Recirculation Operation
The recirculation actuator is a 2-wire bi-directional electric motor. Two control circuits enable the actuator to operate. The control circuits use either ground or a 12-volt value to coordinate the actuator movement. The HVAC control assembly reverses the polarity of the control circuits to move the actuator in the opposite direction. Recirculation is not available in Defrost and Mix-Blend mode.
