1998 JAGUAR X308 temperatur sensor

The solar sensor is mounted on the top surface of the fascia between the defrost outlets.
The sensor is a photo-diode which is calibr ated to measure direct sunlight. It provides an output signal to the A/CCM which
automatically reduces air temperature an d increases fan speed (airflow volume) to compensate for solar heating.
Evaporator Sensor

This thermistor device changes electrical resistance as a result of temperature variations.
The sensor is positioned next to the evaporator fins and measures air temper ature after it has passed through the
evaporator. The sensor inputs a signal to the A/CCM which controls the compress or (see table) when the refrigeration
system is operating.
The sensor's connector is located on the LH side of the air conditioning unit, in front of the main power connector.
The A/CCM disengages the compressor clutch when the temperature of the air off the evaporator is 2° C or less. This is to
prevent the moisture which may collect between the cooling fins of the evaporator from freezing and thus restricting airflow.

Heater Matrix Temperature Sensor
Evaporator Temperature SignalCompressor State
3°CON - clutch engaged
2°COFF - clutch disengaged

The heater matrix temperature sensor is a thermistor which changes its electrical resistance in response to changes in air
temperature converting a temperature rating to an electrical signal.
The sensor connector is located on the RH SIDE of the air conditioning unit. The sensor bead is located inside the unit down-
stream from the heater matrix and measures the 'post-heater' air temperature, before the air is distribu ted to the cabin The
sensor provides a signal to the A/CCM which adjusts the duty ratio of the water valve to provide the required air
temperature from the heater.
Ambient Temperature Sensor
The sensor is a thermistor which changes its electrical resistance in response to changes in air temperature, converting a
temperature rating to an electrical signal.

The ambient temperature sensor measures exterior air temper ature and is mounted on the crossbeam, in front of the
condenser on the LH side.

The signal from the ambient sensor allo ws the A/CCM to compensate for the ambient conditions and to display the
information on the control panel - updated every four (4) seconds.
Sensor response is 'damped' by the A/CCM and ther efore does not appear to react to temperature chan
ges as quickly as the

other sensors. This feature prevents the effects of sudden changes in air outlet temperatures due to factors such as:
Recirculating air from the engine cooling pack at low vehicle speeds Sudden changes in ambient temperature The effects of water splash
Motorised In-car Aspirator.

An intake grille (mounted on the fascia , outboard of the steering column and below the EOD vent) houses the aspirator
thermister. The remotely mounted motor / fan assembly draws ca bin air through the grille and thus over the thermistor; a
flexible hose connects both components.
The electrical resistance of the thermistor changes in response to variations in air temperatur e, this change being converted
into an electrical signal. The A/CCM uses this signal to adjust the temperature, airflow and air distribution from the air
conditioning unit.
Coolant Temperature Signal.
This signal is supplied to the A/CCM from the instrument cluster, the input being required to:
Provide blower inhibit control , to avoid the system in heat ing mode delivering cold air when the coolant temperature is below 35°C unless DEFROST is selected. To progressively increase the fan speed up to maximum blower speed during warm up control. To assist in the control of the outlet temperature. To avoid possible pump or valve damage ca used by ice particles in the coolant.
Compressor ON Signal.
This signal monitors the compressor relay to confirm the compressor operating state and so provide relevant fault
information.
Servo Motor Control.
Flap position, which directs the flow of air through the system, is controlled by servo motors; these may be driven in either
a clockwise or anti-clockwise direction by signals from the A/ CCM. Motor, thus flap position, is monitored via a feedback
potentiometer which is situated within the motor housing.
Servo motors control the following flaps:

Connector Pin Identity Chart for AC003

Connector Pin Identity Chart for AC004

Pin NumberCircuitCircuit Function
001Solar sensor
002Center vent servomotor feedback potentiometer
003RH air intake servomotor feedback potentiometer fresh / recirculation
004Not used
005Cool air bypass servomotor feedback potentiometer
006Coolant temperature signal
007RH blower motor voltage feedback
008RH blower motor drive signal
009Not used
010Defrost servomotor feedback potentiometer
011LH air intake servomotor feedback potentiometer fresh / recirculation
012Not used
013Foot servomotor feedback potentiometer
014Not used
015LH blower motor voltage feedback
016LH blower motor drive signal
Pin NumberCircuitCircuit Function
001Screen request to ECM
002CLOCK signal to control panel
003DATA OUT signal to control panel
004Compressor lock signal
005Exterior air temperature sensor
006Heater matrix temperature sensor
007DATA IN signal from control panel
008START signal to control panel
009Not used
010Compressor lock select
011In-car temperature sensor
012Evaporator temperature sensor

System Self-test
Control Panel Fault Code Listing • NOTE: Reference fault code #23*: In ambient temperatures below 0° C, this code may be logged because the low
ambient causes a tempor ary low gas pressure.
• NOTE: Where the ambient temperature rises above 40° C, with the engine close to overheating, electrical feed to the
compressor clutch may be cut and code #23 registered.
SymptomPossible SourcesAction
0 Normal operation no
fault codes presentNone
*Wait 30 seconds for system
self-check.
*
11 Motorized in-car
aspirator malfunctionHarness / connector fault
Sensor open / short circuit
*
*Panel fault codes are not
stored for motorized in-car
aspirator motor failure.
*
12 Ambient
temperature sensor
malfunctionHarness / connector fault
Sensor open / short circuit
*
*After rectification, disconnect
the vehicle battery for 10
seconds to reset the system.
*
13 Evaporator
temperature sensor
malfunctionHarness / connector fault
Sensor open / short circuit
*
*Refer to PDU
*
14 Water temperature
input malfunctionInstrument cl uster output
*Refer to PDU
*
15 Heater matrix
temperature sensor
malfunctionHarness / connector fault
Sensor open / short circuit
*
*Refer to PDU
*
21 Solar sensorSensor open /short circuit
*Refer to PDU
*
22 Compressor lock
signal faultLow refrigerant charge, low compressor oil level, loose drive
belt Harness / connector fault
*
*Adjust items as required
*
23 Refrigerant pressure
switch malfunctionHarness / connector fault
Switch open / short circuit
*
*Refer to PDU
*
23 Refrigerant pressure
low refrigerant charge * Leak from damaged pipe or joint
*Rectify as required and
recharge system
*
24 Face vent demand
potentiometer faultPotentiometer open / short circuit
Harness / connector fault
*
*Refer to PDU
*
31 LH fresh / recirc.
potentiometer faultHarness / connector fault
In certain circumstances the servo motor may over-travel
and cause further logged faults. This may be cured, following
fault rectification, by cycling the ignition ON-OFF-ON 3 times
*
*Refer to PDU
*
32 RH fresh / recirc.
potentiometer faultHarness / connector fault
In certain circumstances the servo motor may over-travel
and cause further logged faults. This may be cured, following
fault rectification, by cycling the ignition ON-OFF-ON 3 times
*
*Refer to PDU
*
33 Cool air by-pass
potentiometer faultHarness / connector fault
In certain circumstances the servo motor may over-travel
and cause further logged faults. This may be cured, following
fault rectification, by cycling the ignition ON-OFF-ON 3 times
*
*Refer to PDU
*
34 Defrost vent
potentiometer faultHarness / connector fault
In certain circumstances the servo motor may over-travel
and cause further logged faults. This may be cured, following
fault rectification, by cycling the ignition ON-OFF-ON 3 times
*
*Refer to PDU
*
35 Centre vent
potentiometer faultHarness / connector fault
In certain circumstances the servo motor may over-travel
and cause further logged faults. This may be cured, following
fault rectification, by cycling the ignition ON-OFF-ON 3 times
*
*Refer to PDU
*
36 Foot vent
potentiometer faultHarness / connector fault
In certain circumstances the servo motor may over-travel
and cause further logged faults. This may be cured, following
fault rectification, by cycling the ignition ON-OFF-ON 3 times
*
*Refer to PDU
*
41 LH fresh / recirc.
motor faultHarness / connector fault
Servo motor seized or sticking
Flap seized or sticking
*
*
*Refer to PDU
*
42 RH fresh / recirc.
motor faultHarness / connector fault
Servo motor seized or sticking
Flap seized or sticking
*
*
*Refer to PDU
*

Control Components - Air Discharge Temperature Sensor
Removal and Installation
Removal
Installation

1.
Remove heater matrix for access; refer to 82.25.10.

2. Detach sensor connector from heater / cooler assembly.
Disconnect connector.

3. Detach clip and sensor from evaporator.
Remove clip.

4. Remove sensor from heat er / cooler assembly.
Remove clip.
Lever case apart sufficient enough to withdraw sensor
through aperture.
1. Installation is a reversal of the removal procedure.

Control Components - Ambient Air Temperature Sensor
Removal and Installation
Removal
Installation



1. NOTE: The ambient temperature sensor is accessed through
the bumper vane.
Detach sensor from bracket and disconnect connector.
1. Installation is a reversal of the removal procedure.

Instrument Cluster - Ins
trument Cluster
D
iagn
osis and Testing
Tests U
s
ing the Portable Diagnostic Unit
Re
fe
r to PDU User Guide
The c
o
mplexity of the electronics involved with the Instrument Cluster and the two multiplexed communication networks
which are connected to it, preclude the use of workshop genera l electrical test equipment. Therefore, reference should be
made to the PDU User Guide for detailed instructions on testing the Instrument Clus ter and associated circuits.
The PDU systematically test s and analyses all functions of the Instrument Clus ter, the various systems controlled by it and
individual sensors which are attached to each separate system.
Where a fault involving a remote sensor e. g. water temperature sensor, is indicated, before replacing the component, some
basic diagnostic methods may be necessary to confirm that connections are good and that wiring is not damaged.
Diagnostics using the PDU is via the CAN network, accessed at the diagnostic connector on the car.
Replaceable Parts
The only replaceable part s
are, General Illumination Bulbs, Direction Indicator Warning Bu
lbs and Main Beam Warning Bulb,
which are all of the conventional filament type. Other warning lamps are LEDs and are not replaceable.