1998 JAGUAR X308 heater

Installation



Detach heater / cooler unit connector.
Detach evaporator sensor connector.
Disconnect connector.

7. Remove heater / cooler unit upper case from lower case.
Remove screw.
Remove 15 clips.
Remove upper case from lower case.

8. Remove evaporator from case.
Remove sensor and clip.
Remove evaporator.
1. Installation is the reverse of removal.

Control Components - Control Components
Description and Operation
System Controls
The climate control system is controlled by : 1. 1. Manual input from the operator, via the center console located control panel.
2. 2. Automatically by means of the A/CCM.
Output is based upon input from the following devices:
Motorized In-car aspirator External air temperature sensor Coolant temperature sensor Heater 'air-off' (the temperature of the air leaving the matrix fins) temperature sensor Evaporator 'air-off' (the temperature of the air leaving the evaporator fins) temperature sensor Solar sensor Left hand blower recirculation / fresh air flap potentiometer Right hand blower recirculation / fresh air flap potentiometer Upper air distribution box (ADB) center and side face flap servomotor potentiometer ADB defrost flap servomotor potentiometer Air conditioning unit Foot flap servomotor potentiometer Air conditioning unit Cool Air Bypass flap servomotor potentiometer Thumbwheel controls on the facia vent assemblies which provide manu al adjustment of the airflow volume. Road and engine speed signals input to the A/CCM
Climate Control Panel
Communication between the control panel and the A/CCM is via a serial data communications link.

Switching the Climate Control system ON
The climate control system can be switched ON by pressing one of the following :
Ref #1 On / Off (resumes the system on in the previous settings).
Ref #10 A / C (resumes the system on in the previous settings).
Ref #11 AUTO (resumes the system on at the previous temperature setting).

External temperature < -10 °C Vehicle speed > 65 km / h The first two conditions exist > 2 minutes. Engine speed > 50 revs / min
14. 14. Heated Backlight (R)
Pressing the heated backlight button will simultaneously energize the heater elements for timed cycles of;
21 minutes backlight 11 minutes exterior mirrors
Pressing the button again within the 21 minute timer will cancel the request.
If the engine is stalled, or the ignition switched OFF, the backlight and door mirror timers will be cleared, resulting in both
functions being switched off.
• NOTE: Both the backlight and door mirrors may be activated with the climate control system OFF, but the engine must be
running.
15. 15. Temperature Decrease
Pressing this button (BLUE symbol) decreases the interior temperature setting in 1° increments. Should the button be
pressed when the setting temperature is below the lower automatic control temperature limit, the display will indicate 'LO'.
16. 16. Temperature Increase
Pressing this button (RED symbol) will raise the temperature setting in 1° increments Should the button be pressed when
the setting temperature is above the upper automatic control temperature limit, the display will indicate 'HI'.
Automatic Temperature Control Range
°C°F
LOLO
1761
62
1863
64
1965
66
2067
68
2169
70
2271
72
2373
74
2475
76
2577
78
2679
80
2781
82
2883
84
2985
86
3087
88
3189

Inputs / Outputs
1.1. Engine speed:
Input to the A/CCM from the ECM. Heated windshield and backli ght will be inhibited when engine speed < 50 RPM.
2. 2. Vehicle speed:
Input from the instru ment cluster. Blower speed control to minimise the effects of ram ai r. Road speed compensation is inhibited when maximum
cooling LO, or maximum heating HI, is selected; also inhi bited in defrost mode with airflow set to maximum.
Used to determine the frequency at which the exterior temperature display is updated.
3. 3. Coolant temperature (signal derived from ECM via instrument cluster):
Input from the heater matrix temperature sensor used to control water valve and thus vent temperatures. Used to monitor the temperature of coolant at the heater matrix to assist the control of air outlet temperature. Used to inhibit the blowers when heating is selected and the engine coolant temperature is below 30°C. Is used to provide progressive increase in blower speed up to 60°C. To inhibit the water valve and pump when the coolant temperature is = < 10°C
Sensors and Controls
Solar 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

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
*