Auxiliary Climate Control

AUXILIARY CLIMATE CONTROL

Auxiliary Climate Control System
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 Air Distribution
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 and directs airflow through the fixed register to the passenger compartment.

System Airflow:

The auxiliary climate control system has the following features:
- 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 air distribution door are controlled by electronic actuator motors.
- Movement of the auxiliary temperature/mode control between COOL/OVERHEAD and WARM/OVERHEAD causes a corresponding movement of the temperature blend door to mix air flowing through and around the auxiliary heater core and also causes a corresponding movement of the mode door to the ROOF and FLOOR positions.

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.

Control Assembly
The auxiliary climate control system has dual controls for the driver and rear passengers consisting of temperature/air distribution and blower speed. The front auxiliary climate controls are built into the front climate control assembly. The rear auxiliary climate control assembly is mounted in a separate overhead console positioned on the headliner above the second row seating area.

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.

Evaporator Core
The auxiliary climate control system uses a rear evaporator core which operates in the same manner as the front evaporator core.

Thermostatic Expansion Valve

NOTE: An in-line filter is installed in the auxiliary evaporator inlet line at the floorpan spring lock coupling connection. A restriction in this filter may cause misdiagnosis of a failed thermostatic expansion valve. This filter must be inspected before a new thermostatic expansion valve is installed.

A thermostatic expansion valve automatically regulates the flow of refrigerant into the auxiliary evaporator core. It is also the dividing point in the system between low- and high-pressure sides.

The temperature sensing bulb measures the temperature of the refrigerant in the suction line and transmits it to the thermostatic expansion valve. This temperature variation regulates the refrigerant flow to the auxiliary evaporator core.
- When the bulb senses a high temperature, the thermostatic expansion valve opens and floods refrigerant through the auxiliary evaporator core.
- When the bulb senses a low temperature, the thermostatic expansion valve starts closing to shut off the refrigerant to the auxiliary evaporator core.

Underbody Auxiliary A/C Lines

NOTE: An in-line filter is installed in the auxiliary evaporator inlet line at the floorpan spring lock coupling connection. A restriction in this filter may cause misdiagnosis of a failed thermostatic expansion valve. This filter must be inspected before a new thermostatic expansion valve is installed.

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 front auxiliary A/C evaporator inlet line carries high pressure refrigerant liquid from the condenser to evaporator line to the tube-in-tube type auxiliary evaporator line.- The front auxiliary A/C evaporator outlet line carries refrigerant vapor from the tube-in-tube type auxiliary evaporator line to the front evaporator outlet line.
- The tube-in-tube type auxiliary evaporator line combines a high-pressure tube and a low-pressure tube into a single assembly. The high-pressure tube is located inside of, and is separate from the low-pressure tube.
- Four short jumper lines connect the tube-in-tube auxiliary evaporator line to the auxiliary evaporator inlet and outlet. The jumper lines are connected at the floorpan bracket.

Underbody Heater Lines
The underbody auxiliary heater lines have the following features:
- The underbody auxiliary heater inlet line is a 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