Component Description

Rear Auxiliary Climate Control Assembly 

The vehicle has dual climate controls for the auxiliary unit. The front controls are built into the FCIM, and can control the auxiliary unit by means of a temperature selection button and blower speed control, or can transfer control to the rear auxiliary climate control assembly. The rear auxiliary climate control has separate controls for blower speed, temperature blend and airflow mode.

Auxiliary Mode Door Actuator 

The auxiliary mode door actuator moves the auxiliary mode door on command from the HVAC module based on input from either the front or rear auxiliary climate controls.

The auxiliary mode door actuator contains a reversible electric motor and potentiometer. The potentiometer allows the HVAC module to monitor the position of the auxiliary mode door. The potentiometer circuit consists of a 5-volt reference signal connected to one end of a variable resistor, and a signal ground connected to the other. A signal circuit is connected to a contact wiper, which is driven along the variable resistor by the actuator shaft. The signal to the HVAC module from the contact wiper indicates the position of the airflow mode door.

Auxiliary Temperature Blend Door Actuator 

The auxiliary temperature blend door actuator moves the auxiliary temperature blend door on command from the HVAC module based on input from either the front or rear auxiliary climate controls.

The auxiliary temperature blend door actuator contains a reversible electric motor and potentiometer. The potentiometer allows the HVAC module to monitor the position of the auxiliary temperature blend door. The potentiometer circuit consists of a 5-volt reference signal connected to one end of a variable resistor, and a signal ground connected to the other. A signal circuit is connected to a contact wiper, which is driven along the variable resistor by the actuator shaft. The signal to the HVAC module from the contact wiper indicates the position of the airflow temperature blend door.

Auxiliary Blower Motor Speed Control 

The auxiliary blower motor speed control controls the auxiliary blower motor speed, based on input from either the front or rear auxiliary climate controls by converting low power signals from the HVAC module to a high current, variable ground feed for the auxiliary blower motor.

Auxiliary Blower Motor 

The auxiliary climate control system contains a blower motor, which is controlled by either the front or rear auxiliary climate controls.

Auxiliary Evaporator Core 

The auxiliary climate control system uses an evaporator core, which cools and dehumidifies the airflow from the auxiliary blower motor when the A/C compressor is operating. All airflow from the blower motor passes through the evaporator core.

Auxiliary Heater Core 

The heater core consists of fins and tubes arranged to extract heat from the engine coolant and transfer it to air passing through the heater core.

Thermostatic Expansion Valve (TXV) 

The TXV provides a restriction to the flow of refrigerant from the high-pressure side of the refrigerant system and separates the low-pressure and high-pressure sides of the refrigerant system. Refrigerant entering and exiting the evaporator core passes through the TXV through 2 separate flow paths. An internal temperature sensing bulb senses the temperature of the refrigerant flowing out of the evaporator core and adjusts an internal pin-type valve to meter the refrigerant flow into the evaporator core. The internal pin-type valve decreases the amount of refrigerant entering the evaporator core at lower temperatures and increases the amount of refrigerant entering the evaporator core at higher temperatures.

Underbody Auxiliary A/C Lines 

The 2 underbody auxiliary A/C lines are part of a bundle of 4 aluminum tube assemblies of various sizes bracketed together and fastened to the underbody of the vehicle.

The underbody auxiliary A/C lines have these features:

• The underbody auxiliary evaporator A/C liquid line is an aluminum tube assembly that carries refrigerant from the front evaporator liquid inlet supply line to the auxiliary evaporator inlet.
• The underbody auxiliary evaporator A/C suction line is a 15.875 mm (0.625 in) aluminum tube assembly that carries refrigerant from the auxiliary evaporator to the front evaporator outlet suction line.

Underbody Auxiliary Heater Lines 

The 2 underbody auxiliary heater lines are part of a bundle of 4 aluminum tube assemblies of various sizes bracketed together and fastened to the underbody of the vehicle.

The underbody auxiliary heater lines have these features:

• The underbody auxiliary heater inlet line is an aluminum tube assembly that carries coolant from the engine coolant supply line to the auxiliary heater core inlet.
• The underbody auxiliary heater outlet line carries coolant from the auxiliary heater core to the front heater core outlet line.