2010 JAGUAR XFR heating

Published: 11-May-2011
Climate Control - Heating and Ventilation - Component Location
Description and Operation


NOTE: RHD (right-hand drive) vehicle shown, LHD (left-hand drive) vehicle similar.

Component Location



Item Description 1 Ventilation outlet 2 Blower relay (on RJB (rear junction box)) 3 Heater assembly 4 Blower control module 5 Blower 6 ATC (automatic temperature control) module 7 Air inlet duct 8 Auxiliary coolant pump Comments:
All except 3.0L vehicles; 5.0L version shown, 3.0L diesel version similar.

Climate Control - Heating and Ventilation - Overview
Description and Operation

Overview Published: 11-May-2011

The heating and ventilation system controls the temperature and flow of air supplied to the passenger compartment. The
system is a dual zone automatic system, which can provide different temperature settings for the LH (left-hand) and RH
(right-hand) sides of the passenger compartment.

Published: 11-May-2011
Climate Control - Heating and Ventilation - System Operation and Component Description
Description and Operation

Control Diagram

NOTE: A = Hardwired; N = Medium speed CAN (controller area network) bus; O = LIN (local interconnect network) bus; P
= Media orientated system transport (MOST) ring.



Item Description 1 Battery 2 BJB (battery junction box) 3 CJB (central junction box) 4 Auxiliary coolant pump Comments:
all except 3.0L vehicles; 5.0L version shown, 3.0L diesel version similar www.JagDocs.com

Touch screen display (TSD) 6 Integrated control panel 7 Information control module 8 ATC (automatic temperature control) module 9 Face/Feet distribution stepper motor 10 RH (right-hand) temperature blend stepper motor 11 LH (left-hand) temperature blend stepper motor 12 Windshield (defrost) distribution stepper motor 13 Blower control module 14 RJB (rear junction box) 15 Blower
System Operation
Operation of the heating and ventilation system is controlled by the ATC module. Refer to: Control Components (412-01 Climate Control, Description and Operation).
The system can be operated in automatic or manual mode, with temperature settings selected using the switches on the
integrated control panel.

When the engine is running, coolant is constantly circulated through the heater core by the engine coolant pump and the
auxiliary coolant pump. Where fitted, the auxiliary coolant pump is energized by the CJB on receipt of medium speed CAN bus signals from the ATC module. The CJB broadcasts auxiliary coolant pump status over the medium speed CAN bus for use by other vehicle systems.

The blower is supplied with power by the blower relay on the RJB and connected to ground via the blower control module. The blower control module regulates the voltage across the blower motor to control blower speed. The voltage set by the blower
control module is controlled by a PWM (pulse width modulation) signal from the ATC module. The ATC module uses a feedback signal from the blower control module to monitor blower speed.
Refer to: Control Components (412-01 Climate Control, Description and Operation).


Heater Assembly Component Description

The heater assembly controls the temperature and flow of air supplied to the air distribution ducts. The heater assembly is
mounted on the vehicle centerline, between the instrument panel and the engine bulkhead.

The heater assembly consists of a casing that contains an A/C (air conditioning) evaporator, a heater core, two air distribution
control doors and two temperature blend control doors. On 2.7L diesel vehicles, the heater assembly also contains an electric
booster heater.
Refer to: Electric Booster Heater (412-02 Auxiliary Climate Control, Description and Operation).
Mounted on the heater casing are four stepper motors. Each of the stepper motors is connected to either an air distribution
control door or a temperature blend control door.
The A/C evaporator is part of the A/C system. Refer to: Air Conditioning (412-01 Climate Control, Description and Operation).
The heater core provides the heat source to warm the air supplied to the passenger compartment. The heater core is an
aluminum two pass, fin and tube heat exchanger, and is installed across the width of the heater housing. Two aluminum tubes
attached to the heater core extend through the engine bulkhead and connect to the engine cooling system. For additional
information, refer to:
Engine Cooling (303-03A, Description and Operation),
Engine Cooling (303-03B Engine Cooling - V6 3.0L Petrol, Description and Operation), Engine Cooling (303-03C, Description and Operation).

Air Inlet Duct

The air inlet duct connects the fresh air inlet in the engine bulkhead to the heater assembly. The air inlet duct is installed
behind the instrument panel on the passenger side.

The air inlet duct consists of a casing that contains a pollen filter, an air inlet door, a blower and a blower control module. A
recirculation air inlet is incorporated into the casing. A servo motor is mounted on the casing and connected to the air inlet
door, to allow selection between fresh and recirculated air.
Refer to: Control Components (412-01 Climate Control, Description and Operation). The pollen filter is part of the air distribution and filtering system.
Refer to: Air Distribution and Filtering (412-01 Climate Control, Description and Operation).
The blower regulates the volume of air flowing through the air inlet duct to the heater assembly. The blower consists of an
open hub, centrifugal fan and an electric motor.
The blower control module regulates the power supply to the blower motor. The blower control module is installed in the air

Published: 11-May-2011
Climate Control - Air Conditioning - System Operation and Component Description
Description and Operation


General System Operation

To accomplish the transfer of heat, refrigerant is circulated around a sealed system, where it passes through two
pressure/temperature regimes. In each of the regimes the refrigerant changes state, during which process maximum heat
absorption or dissipation occurs.

The low pressure/temperature regime is from the thermostatic expansion valve, through the evaporator to the compressor. The
refrigerant decreases in pressure and temperature at the thermostatic expansion valve, then changes state from a liquid to a
vapor in the evaporator to absorb heat.

The high pressure/temperature regime is from the compressor, through the condenser and receiver drier assembly to the
thermostatic expansion valve. The refrigerant increases in pressure and temperature as it passes through the compressor, then
releases heat and changes state from a vapor to a liquid in the condenser.

Operation of the A/C (air conditioning) system is controlled by the ATC (automatic temperature control) module.
Refer to: Control Components (412-01 Climate Control, Description and Operation). The A/C system works in conjunction with: The air distribution and filtering system.
Refer to: Air Distribution and Filtering (412-01 Climate Control, Description and Operation). The heating and ventilation system.
Refer to: Heating and Ventilation (412-01 Climate Control, Description and Operation).

Climate Control - Control Components - Overview
Description and Operation

Overview Published: 11-May-2011

The climate control system is controlled by the ATC (automatic temperature control) module. It controls the heating and
ventilation system and the A/C (air conditioning) system to regulate the temperature, volume and distribution of air into the
passenger compartment. The system is a fully automatic dual zone system capable of maintaining individual temperature
levels selected for the LH (left-hand) and RH (right-hand) sides of the passenger compartment, up to a maximum differential
of approximately 3 ºC (5.4 ºF). Manual overrides for the system include inlet air source, blower speed and air distribution.
These selections can be made using either the soft switches on the home and climate control screens of the touch screen
display (TSD), or the switches on the integrated control panel.
The ATC module also controls: The rear window heater.
The windshield heater (where fitted).
The exterior mirror heaters.
The seat heaters (where fitted).
The steering wheel heater.
TSD Home Screen



TSD Climate Control Screen

6 TSD (touch screen display) 7 Integrated control panel 8 Evaporator temperature sensor 9 Humidity and temperature sensor 10 Sunload sensor 11 Refrigerant pressure sensor 12 Pollution sensor Comments:
where fitted 13 Air inlet servo motor 14 A/C (air conditioning) compressor solenoid valve 15 RH (right-hand) outer face level register 16 RH inner face level register 17 LH (left-hand) inner face level register 18 LH outer face level register 19 RH temperature blend stepper motor 20 Face/Feet distribution stepper motor 21 ATC (automatic temperature control) module 22 LH temperature blend stepper motor 23 Windshield (Defrost) stepper motor 24 Blower control module 25 RJB (rear junction box) 26 Blower


Air Inlet Control System Operation

The source of inlet air is automatically controlled unless overridden by pressing the air recirculation switch on the integrated
control panel. During automatic control, the ATC module determines the required position of the recirculation door from its 'comfort' algorithm and, if fitted, the pollution sensor.

The ATC module provides analogue signals to the air inlet servo motor along a hardwired connection. A potentiometer in the motor supplies the ATC module with a position feedback signal for closed loop control.
Air Temperature Control

Cooled air from the evaporator enters the heater assembly, where temperature blend doors direct a proportion of the air
through the heater core to produce the required output air temperature.

The two temperature blend doors operate independently to enable individual temperature settings for the left and right sides
of the passenger compartment. The temperature blend doors are operated by stepper motors, which are controlled by the ATC module using LIN bus messages.
The ATC module calculates the temperature blend stepper motor positions required to achieve the selected temperature and compares it against the current position. If there is any difference, the ATC module signals the stepper motors to adopt the new position.

Air temperature is controlled automatically unless maximum heating (HI) or maximum cooling (LO) is selected. When maximum
heating or cooling is selected, a 'comfort' algorithm in the ATC module adopts an appropriate strategy for air distribution, blower speed, and air source.

Temperature control in one side of the passenger compartment can be compromised by the other side of the passenger
compartment being set to a high level of heating or cooling. True maximum heating or cooling (displayed as 'HI' or 'LO' on the
TSD) can only be selected for the driver's side of the passenger compartment. If 'HI' or 'LO' is selected for the driver's side, the
temperature for the front passenger's side is automatically set to match the driver's side.

If A/C is selected off in the automatic mode, no cooling of the inlet air will take place. The minimum output air temperature from the system will be ambient air temperature plus any heat pick up in the air inlet path.

If the Temp. sync. soft button on the TSD is pressed, the ATC module synchronizes the temperature of the passenger side of the passenger compartment with the driver's side.

Blower Control

When the system is in the automatic mode, the ATC module determines the blower speed required from a comfort algorithm. When the system is in the manual mode, the ATC module operates the blower at the speed selected using either the rotary

rear window heater switch is pressed or the engine stops.

Automatic operation during a journey is initiated when low ambient air temperatures are experienced and the vehicle has been
travelling for a set period of time above a threshold speed. In this instance, no feedback is given to the driver to inform him
the rear window heater is operational (the switch LED is not illuminated). The duration of heater operation is variable depending on the ambient air temperature, vehicle speed and the amount of time the vehicle has been travelling.

Windshield Heater (Where Fitted)

Windshield heater operation is only enabled when the engine is running. The ATC module controls operation of the windshield heater using two relays in the EJB (engine junction box). When windshield heater operation is required, the ATC module broadcasts a message to the CJB on the medium speed CAN bus. On receipt of the message, the CJB energizes the relays by providing a ground path for both relay coils. This allows a battery feed to flow across the relays to power the windshield left
and right heater elements.
There are two modes of windshield heater operation; manual and automatic.

Manual operation is activated by pressing the windshield heater switch on the integrated control panel. When the switch is
pressed, the status LED in the switch illuminates and the windshield heater elements are energized. Manual operation is discontinued when the windshield heater switch is pressed a second time, 5 minutes have elapsed (the heating phase), or the
engine stops. If manual operation is discontinued by the engine stopping, the previous heating phase is resumed if the engine
is re-started within 30 seconds.

There are two variants of automatic operation; automatic operation at the start of a journey and automatic operation during a
journey.

Automatic operation at the start of a journey is initiated if the ambient air temperature is below 5 °C (41 °F). In this instance,
the switch LED is illuminated and the heater elements are energized for 6.5 minutes. Automatic operation is discontinued if the windshield heater switch is pressed or the engine stops.

Automatic operation during a journey is initiated when low ambient air temperatures are experienced and the vehicle has been
travelling for a set period of time above a threshold speed. In this instance, no feedback is given to the driver to inform him
the windshield heater is operational (the switch LED is not illuminated) and the duration of operation is variable depending upon the ambient air temperature, vehicle speed and the amount of time the vehicle has been travelling.

Exterior Mirror Heaters

Operation of the exterior mirror heaters is fully automatic and not controllable by the driver. Exterior mirror heater operation is
determined by ambient air temperature and windshield wiper status. When ambient air temperature reaches a pre-determined
level, the ATC module broadcasts an exterior mirror heating request to the door modules over the medium speed CAN bus. On receipt of this message, the door modules provide feed and ground connections to both exterior mirror heater elements.

The amount of time the exterior mirror heaters are operational increases if the windshield wipers are switched on. This ensures
the mirrors remain mist free in damp and wet conditions, where there is an increased risk of misting.

Seat Heaters (Where Fitted)

There are four seat heater settings available; off, 1, 2 and 3, which can be selected on the home and climate control screens
of the TSD. The heat setting is relayed to the vehicle occupants through a graduated display on the TSD.

Operation of the heated seats is controlled by the ATC module. When the ATC module receives a heating request from the TSD, it broadcasts a message to the CJB over the medium speed CAN bus. The CJB then provides a hardwired 12 V supply to the three heater elements in the related front seat. The heater elements, two in the seat cushion and one in the seat squab,
are wired in series. The ATC module monitors seat temperature using a temperature sensor located in each seat cushion. The CJB provides the temperature sensors with a 5 V supply. The level of the returned voltage back to the CJB is proportional to the seat temperature. The value of the return signal is broadcast to the ATC module, over the medium speed CAN bus, which allows it to control the seat temperature to the required level. The ATC module will suspend or disable operation of the seat heaters if any of the following occur:

Battery voltage exceeds 16.5 ± 0.3 V for more than 5 seconds. Seat heating is re-enabled when battery voltage
decreases to 16.2 ± 0.3 V.
If a short or open circuit is detected.
If the seat heat temperature rises significantly above the target temperature setting.

The graduated display on the TSD remains illuminated until the seat heaters are turned off or the engine stops. If the engine
is restarted within 30 seconds the seat heater resumes the previous heating level.