Front Auxiliary HVAC Control Assembly
The front auxiliary HVAC control assembly provides inputs to the rear auxiliary HVAC control module. It is located in the overhead console so that front seat occupants can control auxiliary HVAC operation. This assembly provides blower, air delivery mode, air temperature settings and control of which control unit will operate the auxiliary HVAC system. When the REAR position is selected, inputs from this control assembly will not be processed by the rear auxiliary HVAC control module. When OFF position is selected the auxiliary system is inoperative. The module is turned on by ignition voltage from the ignition 3 voltage circuit.
Inside Air Temperature Sensor Assembly
The HVAC control module receives an input of the passenger compartment air temperature from the inside air temperature sensor assembly. A fan located internally to the inside air temperature sensor assembly housing continually draws passenger compartment air over the sensor.
The inside air temperature sensor is a Negative Temperature Coefficient (NTC) thermistor, when the temperature of the sensor changes so does the resistance across the thermistor. When the air temperature is warm, the sensor resistance and signal voltage is low. When the air temperature is cool, the sensor resistance and signal voltage is high. Inside the HVAC control module 5 volts is supplied to the inside air temperature signal circuit through a fixed resistance. The fixed resistance inside the HVAC control module makes the signal circuit a series circuit. As the resistance of the sensor changes, the amount of voltage it drops also changes since it is in series with the fixed resistance inside the HVAC control module. The HVAC control module monitors the voltage drop of the circuit which is needed to calculate the air temperature. The ground for the inside air temperature sensor is provided by the low reference circuit.
The HVAC control module will use a default value for the inside air temperature signal if there is a fault with the input. This value will be displayed on the scan tool. The HVAC control module will use this default to ensure HVAC operation is still performed.
The front auxiliary HVAC control assembly provides inputs to the rear auxiliary HVAC control module. It is located in the overhead console so that front seat occupants can control auxiliary HVAC operation. This assembly provides blower, air delivery mode, air temperature settings and control of which control unit will operate the auxiliary HVAC system. When the REAR position is selected, inputs from this control assembly will not be processed by the rear auxiliary HVAC control module. When OFF position is selected the auxiliary system is inoperative. The module is turned on by ignition voltage from the ignition 3 voltage circuit.
The front auxiliary HVAC control assembly provides inputs to the auxiliary HVAC control processor. It is located in the overhead console so that front seat occupants can control auxiliary HVAC operation. This assembly provides blower, air delivery mode, air temperature settings and control of which control unit will operate the auxiliary HVAC system. When the REAR position is selected, inputs from this control assembly will not be processed by the auxiliary HVAC control processor. This system does not have Class 2 communication available.
The front auxiliary HVAC control assembly receives power from the ignition 3 voltage circuit. Ground is provided by the ground circuit to a splice pack. The front HVAC control assembly will apply a ground to the rear auxiliary enable control circuit when REAR is selected. When the air temperature knob is rotated a variable resistor internal to the assembly will vary a 12 volt input. The 12 volt varied voltage is supplied to the auxiliary HVAC control processor for an auxiliary air temperature actuator position change request. This is done on the auxiliary air temperature door position signal circuit. When the voltage signal is low a cool air request is made and when the voltage signal is high a warm air request is made.
Rear Auxiliary HVAC Control Assembly
The rear auxiliary HVAC control assembly provides inputs to the auxiliary HVAC control processor. It is located in the rear headliner so that second row seat occupants can control auxiliary HVAC operation. This assembly provides blower, air delivery mode and air temperature settings. When the REAR position is selected, on the front HVAC control assembly, inputs from this control assembly will be processed by the auxiliary HVAC control processor. This system does not have Class 2 communication available.
The rear auxiliary HVAC control assembly receives power from the ignition 3 voltage circuit. Ground is provided by the ground circuit through the rear auxiliary HVAC control assembly. The front HVAC control assembly will apply a ground to the rear auxiliary enable control circuit when REAR is selected. When the air temperature knob is rotated a variable resistor internal to the assembly will vary a 12 volt input. The 12 volt varied voltage is supplied to the auxiliary HVAC control processor for an auxiliary air temperature actuator position change request. This is done on the auxiliary air temperature door position signal circuit. When the voltage signal is low a cool air request is made and when the voltage signal is high a warm air request is made.
The front auxiliary HVAC control assembly is located in the front headliner. This controller controls all auxiliary HVAC operation. This assembly provides blower, air delivery mode and air temperature settings. This system does not have Class 2 communication available.
The front auxiliary HVAC control assembly receives power from the ignition 3 voltage circuit. Ground is provided by the ground circuit to a splice pack. When the air temperature knob is rotated a variable resistor internal to the assembly will vary a 12 volt input. This 12 volt varied signal is then sent to the auxiliary air temperature actuator for a change in door position. This is done on the auxiliary air temperature door position signal circuit. When the voltage signal is low a cool air request is made and when the voltage signal is high a warm air request is made.