Auxiliary Climate Control

The auxiliary climate control housing is located on the LH side of the vehicle between the side windows and the floorpan, behind the rear wheel well. The driver has primary control of the auxiliary climate control system or can transfer control to a rear passenger control panel.

All of the auxiliary climate control system components are serviceable from the inside of the vehicle except the lines.

Auxiliary System Airflow

The auxiliary climate control system has the following features:

• A vertical air distribution duct supplies air to the integral headliner air distribution duct. Airflow is then directed to the passengers through adjustable registers. The heater floor duct supplies air to a fixed register, which is integral to the side trim panel.
• The auxiliary blower motor recirculates the air inside the vehicle. Outside air is not available to the auxiliary climate control system.
• Air is cooled and dehumidified by the auxiliary evaporator core only if the main (front) climate control assembly is adjusted to a position that requires A/C compressor operation.
• The temperature blend door and the airflow mode door are controlled by electric actuator motors.
• Movement of the auxiliary temperature/mode control between COOL and WARM causes a corresponding movement of the temperature blend door to mix air flowing through and around the auxiliary heater core. Selection of the auxiliary mode control buttons causes a corresponding movement of the mode door to direct airflow to the ROOF and FLOOR positions.

Auxiliary Blower Motor

The auxiliary climate control system contains a blower motor, which is controlled by the blower motor switch on the front or rear auxiliary climate control assembly. The auxiliary blower motor is mounted to the auxiliary climate control housing behind the LH quarter trim panel.

Auxiliary Climate Control Assembly

The vehicle has dual climate controls for the auxiliary unit. The front controls are built into the Front Controls Interface Module (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 assembly is installed at the rear of the floor console and has separate controls for blower speed, temperature blend and airflow mode.

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.

Auxiliary Heater Tube-to-Heater Core Joint

The heater core inlet and outlet tubes can each be separated from the heater core at the joints where they enter the core. The joints are each sealed using an O-ring seal, and are each secured with a clamp. It is not required to install new heater core inlet and outlet tubes when installing a new heater core unless they are damaged or are leaking independently from the core.

Thermostatic Expansion Valve (TXV)

The Thermostatic Expansion Valve (TXV) is located behind the LH rear quarter trim panel at the auxiliary evaporator inlet and outlet. 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 underbody auxiliary A/C lines carry refrigerant to the auxiliary A/C evaporator inlet, and away from the auxiliary A/C evaporator outlet. The auxiliary underbody lines have the following characteristics:

• The auxiliary evaporator inlet line carries high-pressure refrigerant liquid from the TXV manifold and tube assembly to the auxiliary evaporator.
• The auxiliary evaporator outlet line carries refrigerant vapor from the auxiliary evaporator to the TXV manifold and tube assembly.

Underbody Heater Lines

The underbody auxiliary heater lines have the following 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.