Ok, I looked up the description & operation, which I have enclosed.
I just learned something new also!
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|DESCRIPTION AND OPERATION: AUXILIARY CLIMATE CONTROL || Procedure SGML ID: N912105 |
| SECTION 412-02: Auxiliary Climate Control || 2011 E-Series Workshop Manual |
| DESCRIPTION AND OPERATION || Procedure revision date: 08/21/2010 |
Auxiliary Climate Control
An optional auxiliary climate control system is available. The auxiliary climate control housing is located on the LH side of the vehicle behind the rear wheel well.
Control of the auxiliary climate control system is accomplished using the front (main) climate control assembly on the instrument panel. No auxiliary climate control assembly is present for the rear passengers.
Vehicles with trim have a vertical duct that supplies air to the integral headliner A/C duct. Air is supplied to the passengers through six adjustable registers. The floor duct is integral to the side trim panel and has 4 fixed registers. The trim panel connects directly to the auxiliary A/C-heater unit.
Vehicles without trim do not have overhead registers or floor ducts. A unique register is used to distribute air-conditioned air and a heater outlet duct assembly distributes heated air.
The function selector switch (located in the front A/C control) controls the air distribution for both the front and auxiliary systems.
Airflow mode and temperature blend are accomplished using a single vacuum control motor which operates a single airflow mode door. When the function selector switch is in the DEFROST, FLOOR or MIX position, all airflow is directed through the auxiliary heater core to the floor outlet. Therefore only heated air is available from the auxiliary system when in the DEFROST, FLOOR or MIX mode regardless of the temperature selected for the front (main) airflow outlets.
When the function selector switch is in the VENT, NORM A/C, or MAX A/C mode, all airflow is directed through the auxiliary evaporator core to the overhead registers (if equipped) or the upper airflow outlet. Therefore only cooled air will be available from the auxiliary system in the NORM A/C or MAX A/C mode regardless of the temperature selected for the front (main) airflow outlets. Only ambient temperature air is available from the auxiliary system in the VENT mode because the A/C compressor is not operational in this mode.
The auxiliary system uses only recirculated air from inside the vehicle. Fresh (outside) air is not available from the auxiliary system.
The auxiliary climate control assembly contains a blower motor. It is controlled by the blower motor switch on the front climate control assembly.
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.
A/C Evaporator Core
The evaporator core is the plate/fin type. A mixture of refrigerant and oil enters the bottom of the evaporator core through the evaporator core inlet tube and is routed so it flows through the partitioned plate/fin sections. Refrigerant then moves out of the evaporator core through the evaporator core outlet tube.
Thermostatic Expansion Valve (TXV)
NOTE: The Thermostatic Expansion Valve (TXV) is not separately serviceable. It is serviced only with the evaporator core as an assembly.
A TXVregulates the flow of refrigerant into the auxiliary evaporator core. It is also the dividing point in the auxiliary portion of the refrigerant system between the low- and high-pressure sides.
The TXVincludes a temperature sensing bulb which measures the temperature of the refrigerant in the suction line and transmits it to the TXV. This temperature variation regulates the refrigerant flow to the auxiliary evaporator core.
- When the bulb senses a high temperature, the TXVopens to increase refrigerant flow through the auxiliary evaporator core.
- When the bulb senses a low temperature, the TXVstarts closing to decrease refrigerant flow to the auxiliary evaporator core.