1998 JAGUAR X308 AUTOMATIC

Refrigeration Cycle

The Compressor draws low pressure, lo
w te
mperature, refrigerant from the evaporat or and, by compression, raises the
refrigerant temperature and pressure. High pressure, hot, vaporized refr igerant enters the condenser, where it is cooled by
the flow of ambient air. A change of state occurs as the refrigerant cools in the condense r and it becomes a reduced
temperature, high pressure, liquid.
From the condenser, the liquid passes into the receiver drier which has three functions:
Storage vessel
for varying sy
stem refrigerant demand.
F
ilter to remove sy
stem contaminants.
Mo
isture removal via the dessicant.
With the passage through the receiver drie r completed, the liquid refrigerant, still at high pressure, enters the expansion
valve where it is metered through a contro lled orifice, which has the effect of reducing the pres sure and temperature. The
refrigerant, now in a cold atomized st ate, flows into the evaporator and cools the air passing through the matrix.
As heat is absorbed by the refrigerant, it once again changes state, into a vapor, and returns to the compressor for the
cycle to be repeated.
An automatic safety valve is incorporated in the compressor, which will operate if the system pressure rises above 41 bar.
The valve will reseat when the pressure drops below 27,6 bar.
It
em
Par
t Number
De
scription
1—Compre

ssor
2—Conden

ser
3—Re

ceiver drier
4—Expans

ion valve
5—Evaporator


6—4

-level pressure switch


The terms 'high' and 'low'

pressure (or si
de) refer to the pres sure differential betw een the compressor and expansion valve
ports. This differential is critical to sy stem fault diagnosis and efficiency checks.

Connect hose.
Install bolt (8-10 Nm).

6. Connect compressor to condenser discharge line at condenser.
Remove blanking plugs.
Install new O-ring seal an d lubricate with clean A/C
compressor oil.
Connect hose.
Install bolt (8-10 Nm).

7. Connect transmission o il cooler upper pipe.
Remove blanking plugs.
Install new O-ring seal and lu bricate with clean automatic
transmission fluid.
Connect union nut to radiator and tighten.

8. Connect transmission oil cooler lower pipe.
Remove blanking plugs.
Install new O-ring seal and lu bricate with clean automatic
transmission fluid.
9. Connect radiator blee d hose to radiator.

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).

8.8. Automatic
Symbol indicates when the control of , temperature, fan speed and air distribution are all in Auto mode.
9. 9. External
There are two modes of external ambient temperature selection;
Quick Display. Pressing the button for <1.5 seconds (con firmed by a single bleep) will display the external
temperature for 4 seconds.
Continuous Display. Pressing and holding the button fo r >1.5 seconds (confirmed by two beeps) displays the
external ambient temperature continuously, the value of which will be updated every 4 seconds given that vehicle
road speed is > 25 km/h. Pressing the button again fo r <1.5 seconds resets to the previous display.
• NOTE: Continuous external temperature display will be cancel led when the ignition is switched OFF but not during engine
cranking.
10. 10. A/C
This push-on / push-off button will either select or deselect (as indicated by the state lamp) the refrigeration system.
The refrigeration system is automatically engaged when the Auto button is pressed.
• NOTE: Interior misting of screens may be reduced by continuous operation of th e refrigeration system.
11. 11. Auto
When selected and the state lamp lit, A/C mode will be operat ional and control of vent outlet temperature, fans speed and
air distribution will be automatic.
AUTO mode will disengage should manual air distribution or defrost buttons be operated or the manual fan speed knob be
rotated.
• NOTE: Automatic temperature control is constantly main tained irrespective of selected manual overrides.
12. 12. Defrost
Push-on push-off button, which when engaged will direct all air to the front and side glass at maximum fan speed. The
heated windshield (if fitted) will also be energized for a timed cycle of 6,5 minute s, but may be cancelled by pressing the
HEATED WINDSHIELD (F) button. Pressing 'DEF' again will retu rn to the last setting with automatic temperature control
being maintained.
Directing warm and humid air onto a cold screen can produce interior misting of screens. Operating the climate control
system without the refrigerati on system operating will exacerbate this problem.
• NOTE: Directing cold air onto the screen in warm humid conditions can produce external condensation.
13. 13. Heated Windshield (F)
Pressing the heated windshield button (whe re fitted) will energize the electrically heated windshield elements for a timed
cycle of 6,5 minutes; pressing the button again will cancel the request. Should the engine stall or the ignition be turned
OFF, the timer will be cleare d and the function cancelled.
• NOTE: The heated windshield may be activated with the cl imate control system OFF but the engine must be running.
In very cold ambient temperatures, icing of the interior of the glass is possible when the climate control system is operating
in AUTO mode; to reduce this poss ibility the A/CCM provides automatic operation of the heated windshield.
With the following conditions met, the heated windshield will automatically energize but the state lamp will NOT be lit.

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

LO demands the maximum COOLING performance from the system with the blowers operating automatically at maximum
speed.
HI demands the maximum HEATING performance from the system with the blowers operating automatically at maximum
speed.
Pressing and holding either temperature selection button co ntinuously changes the setting temperature by steps of 1°,
every 0.4 seconds.
• NOTE: The interior temperature does not change when the temperature scale is changed between Celsius and Fahrenheit,
however the temperature display will chan ge to the nearest equivalent number.
Examples:
17C 61F 17C 66F 19C 66F
• NOTE: When operating in HI or LO mode and the AUTO butt on is pressed, the system will adopt the nearest automatic
control temperature setting:
LO AUTO DISPLAY INDICATES 17° C or 61° F HI AUTO DISPLAY INDICATES 31° C or 90° F
• NOTE: When switching the system on us ing the AUTO button, the system will display the previous temperature setting,
except under the following conditions:
LO, system OFF, auto display indicates 17° C or 61° F HI, system OFF, auto display indicates 31° C or 90° F
17. 17. Face
Pressing this button will direct all airflow to the center and side face vents only; pressing again will return the system to
automatic control mode.
• NOTE: When in AUTO mode and in a hot c limate, a bleed of cold air is delivered to foot level. This bleed automatically
shuts off when the inte rior temperature has cooled sufficiently.
18. 18. Bi-Level
This push-on / push-off button will direct air to the center and side face vent s and the front footwells. Pressing the button
(off) will return the system to automatic control mode.
19. 19. Foot
This push-on / push-off button will direct the majority of airflow to the front footwells with a small bleed of air to the fron t
and side screens. Pressing the button (off) will return the system to automatic control mode.
20. 20. Demist
Pressing this button will direct air to the front and side screens and the front foot wells. Pressing the button (off) will return
the system to automatic control mode.
Fascia Air Outlets
90
HIHI

Parts List
Air temperature from the centre (and EOD) vents is slightly cooler than the foot outlets; however this temperature cannot
be varied independently.
The EOD vents, not shown, feature similar controls.
Automatic Operation
Initial setting
Should a new A/CCM be fitted, it will 'power-up' in the OFF mode; switching ON will result in the following settings:
After initial start up the system operating conditions will be st ored in the A/CCM to the conditions which prevailed prior to
ignition OFF.
Maximum Heating / Cooling
Maximum Heating (temperature setting HI)
ItemPart NumberDescription
1—Airflow control
2—Air direction control
FeatureStatus
Setting temperature24°C or 75°F
LH and RH blower assembly recirculation / fresh flapFresh mode
Control modeAutomatic 'AUTO' displayed
BlowerAuto
Compressor outputA/C ON
Heated windshield and mirrorsOFF
Water valveAuto temperature control
ItemControlOverride Allowed
Water valveFully open (not energised)-
BlowerMaximumYes
Fresh / recircFreshYes
Air distributionFeet (state lamp OFF)Yes
A/C systemOFFYes
Cool air by-passFully closed-

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