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bus. Temperature control for the heater element is provided by the steering wheel heater control module which receives a
temperature feedback signal from a NTC (negative temperature coefficient) thermistor located within the steering wheel.
ATC Module Component Description
The ATC module is mounted on the outboard end of the air inlet duct, behind the front passenger side of the instrument panel. The ATC module processes inputs from the TSD, the switches on the integrated control panel and the system sensors. In response to these inputs, the ATC module outputs control signals to the A/C system and the heating and ventilation system.
Two electrical connectors provide the interface between the ATC module and the vehicle wiring. The ATC module uses hardwired inputs from the system sensors, the LIN bus to communicate with the stepper motors and the medium speed CAN bus to communicate with other control modules on the vehicle.
A/C Compressor Solenoid Valve
The A/C compressor solenoid valve is integral with the A/C compressor. Operation of the solenoid valve is controlled by the ATC module using a hardwired drive current of differing values. By controlling the flow of refrigerant through the compressor, the
solenoid valve can control the A/C system pressure and the evaporator operating temperature.
Refrigerant Pressure Sensor
The refrigerant pressure sensor provides the ATC module with a pressure input from the high pressure side of the refrigerant system. The refrigerant pressure sensor is located in the refrigerant line between the condenser and the thermostatic
expansion valve.
The ATC module supplies a 5 V reference voltage to the refrigerant pressure sensor and receives a return signal voltage, between 0 V and 5 V, related to system pressure.
The ATC module uses the signal from the pressure sensor to protect the refrigerant system from extremes of pressure. The ATC module transmits the A/C pressure, along with the compressor drive current value, to the instrument cluster on the medium speed CAN bus. These signals are broadcast to the ECM on the high speed CAN bus to allow it to calculate the torque being applied to the engine by the compressor. www.JagDocs.com
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pressure:
Decreases to 2.1 ± 0.2 bar (31.5 ± 3 lbf/in²); the ATC module loads the A/C compressor again when the pressure increases to 2.3 ± 0.2 bar (33.4 ± 3 lbf/in²).
Increases to 31 ± 1 bar (450 ± 14.5 lbf/in²); the ATC module loads the A/C compressor again when the pressure decreases to 26 ± 1 bar (377 ± 14.5 lbf/in²).
Evaporator Temperature Sensor
The evaporator temperature sensor is a NTC thermistor that provides the ATC module with a temperature signal from the downstream side of the evaporator. The evaporator temperature sensor is mounted directly onto the evaporator matrix fins.
The ATC module uses the input from the evaporator temperature sensor to control the load of the A/C compressor and thus the operating temperature of the evaporator.
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A capacitive sensor element to measure humidity.
A motor driven fan to draw air through the sensor and over the sensing elements.
The humidity sensor element is built out of a film capacitor on different substrates. The dielectric is a polymer which absorbs
or releases water proportional to the relative humidity of the air being drawn through the sensor, and thus changes the
capacitance of the capacitor. For protection, the sensor element is contained in a nylon mesh cover.
Humidity within the passenger compartment is controlled by raising and lowering the evaporator temperature. An increase in
evaporator temperature increases the moisture content of the air entering the passenger compartment. Lowering the
evaporator temperature reduces the moisture content of the air entering the passenger compartment. Humidity and Temperature Sensor
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1 LH door mirror 2 Ambient air temperature sensor The ambient air temperature sensor is a NTC thermistor that provides the ATC module with an input of external air temperature. The sensor is hard wired to the ECM and its signal is transmitted to the instrument cluster on the high speed CAN bus. The instrument cluster acts as a gateway and transmits the ambient air temperature signal to the ATC module on the medium speed CAN bus. The sensor is installed in the LH door mirror, and is accessed by removing the mirror glass, cap and actuator.
Sunload Sensor
The sunload sensor consists of two photoelectric cells that provide the ATC module with inputs of light intensity; one as sensed coming from the left of the vehicle and one as sensed coming from the right. The inputs are a measure of the solar
heating effect on vehicle occupants, and are used by the ATC module to adjust blower speed, temperature and distribution to improve comfort.
The sensor is installed in the speaker grill on the upper surface of the instrument panel. Power for the sensor is provided by a
5 V feed from the instrument cluster.
The sensor also contains the active anti-theft alarm indicator.
Refer to: Anti-Theft - Active (419-01 Anti-Theft - Active, Description and Operation). Ambient Air Temperature Sensor
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Climate Control - Ambient Air Temperature Sensor
Removal and Installation
Removal
NOTE: Removal steps in this procedure may contain installation details. Published: 11-May-2011
1. Refer to: Exterior Mirror Cover (501-09 Rear View Mirrors, Removal and Installation).
2.
3. www.JagDocs.com
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Installation
9.
10.
NOTE: Some variation in the illustrations may occur,
but the essential information is always correct.
WARNING: Only use moderate force when installing
the sensor.
CAUTIONS:
Make sure the evaporator temperature sensor harness
does not become trapped.
Make sure that the sensor is correctly installed.
NOTE: Some variation in the illustrations may occur,
but the essential information is always correct.
1. To install, reverse the removal procedure.
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Climate Control - In-Vehicle Temperature Sensor
Removal and Installation
Removal
NOTE: Removal steps in this procedure may contain installation details. Published: 11-May-2011
1. Refer to: Glove Compartment (501-12 Instrument Panel and Console, Removal and Installation).
2.
Installation
1. To install, reverse the removal procedure.
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7 ECT (engine coolant temperature) sensor 8 Ambient temperature sensor 9 Electric booster heater 10 Face/Feet distribution stepper motor 11 RH (right-hand) temperature blend stepper motor 12 LH (left-hand) temperature blend stepper motor 13 Windshield (defrost) distribution stepper motor 14 ATC (automatic temperature control) module 15 150 A megafuse
General System Operation
Operation of the electric booster heater is controlled by the ATC module, which communicates with the micro-controller in the booster heater using the LIN bus. The temperature requested by the ATC module is based on:
The ambient air temperature.
The engine coolant temperature.
The temperatures selected on the integrated control panel.
The blower must be running for the electric booster heater to operate.
If electrical load management is in force, electric booster heater performance is reduced. For additional information, refer to:
Electronic Engine Controls (303-14A, Description and Operation),
Electronic Engine Controls (303-14B Electronic Engine Controls - V6 3.0L Petrol, Description and Operation), Electronic Engine Controls (303-14C, Description and Operation).
Electric Booster Heater Component Description
The electric booster heater is installed in the heater assembly, on the downstream side of the heater core. It consists of
ceramic coated thermistor elements, rated at 1.25 kW, and a micro-controller. Electrical power for the booster heater is
supplied by the BJB via a 150 A megafuse installed under the RH front seat.
