1998 JAGUAR X308 cooling system

Probable
causes of faults may be found by comparing actual
system pressures, registered on your manifold gauge set or
recovery / recharge / recycle station, and the relevant pressure to temperature relationship graph. The following chart
shows the interpretation that ma y be made by this difference.
• NOTE: The A/CCM will disengage the compressor clutch should the evaporator temperature fall to 0°C.
• NOTE: Graphs are typical for HFC 134A
The 'Normal' condition is that which is relevant to the prevailing evaporator temperature.
System Pressure Fault Classification
• NOTE
: If erratic or unusual gauge move
ments occur, check the equipment against a known (calibrated) manifold gauge
set.
This table should be used in conjunction with the graphical representations of 'High side' pressure / ambient temperature
and 'Low side' pressure / evaporator temperature.
Leak
Test
F
a
ults associated with low re
frigerant charge weight and low pressure ma y be caused by leakage. Leaks traced to
mechanical connections may be caused by to rque relaxation or joint face contamination. Evidence of oil around such areas
is an indicator of leakage.
Models that have fluorescent tracer dye incorporated into the refrigeration system can be checke d for non-apparent leaks by
scanning with a high intensity ultraviolet lamp. The location of leaks can be pinpointed by the bright yellow glow of the
tracer dye.
CAUTION: Observe ALL safety precautions associated with ultraviolet equipment.
Should a leak be traced to a joint, check that the fixing is secured to the correct tightening torque before taking any other
action.
When examining the system for leaks, chec k the compressor shaft seal and evaporator.
Charge Re
covery (system depressurization)
The process of
charge r
ecovery will depe
nd on the basic characteristics of your chosen recovery / recycle / recharge
equipment, therefore, follow the manu facturer's instructions carefully.
Remember that compressor oil may be drawn out during this process, take note of the quantity recovered so that it may be
Lo
w side
gauge reading
High s i
de
gauge reading
Fau l
t
Cause
No
r
mal
No
r
mal
Di
sc
harge air initially cool then
warms up
Mois
ture in system
N
ormal
to low
No
r
mal
As aboveAs above
LowLowD
i
scharge air slightly cool
Ref
r
igerant charge low
LowLowDi

scharge air warm
Refr
igerant charge very low
LowLowDi

scharge air slightly cool or frost
build up at expansion valve
Expansion valve st
uck closed
LowLowDi

scharge air slightly cool,
sweating or frost after point of restriction
Restri
ction in High side of system
HighLowCompressor noisyDe
fe
ctive compressor reed valve
HighHighD
i
scharge air warm and high side
pipes hot
Refri
gerant charge high or inefficient condenser
cooling due to air flow blockage or engine cooling fans
not working
HighHighD i
scharge air warm / Sweating or
frost at evaporator
Expans ion valve st
uck open

Sym
ptom #2
Sy
mptom #2
Sym

ptom #3
Sy
mptom #3
No
cooling
Compressor sei
zed
Compressor seal failure
Compressor valve or piston damage
*
*
*
R
enew compressor
*
Compressor cl
utch / circuit faulty
*
R
efer to PDU
*
D
rive belt slack / broken
*
Adjust or r
enew
*
B
lower motor / circuit faulty
Pressure switch / circuit fault
*
*
R
efer to PDU
*
Total l
oss of refrigerant caused by broken pipe or joint
*
Repair / renew. Check code 2
3
*
P
artial loss of refrigerant caused by leaking joint or pipe
*
R
epair / renew, check fault code #23
*
Conden
ser damage
*
Re
new, check fault code #23
*
Bl
ocked receiver / drier filter
*
R
enew receiver / drier
*
Evaporator senso
r / circuit faulty
*
R
efer to PDU, check fault code #13
*
Bl
ocked pollen filter (if fitted)
*
Cle
an or renew
*
• NOTE: Should a leak or low refrigerant be established as the cause of INSUFFICIENT COOL ING, follow the procedures
Recovery / Recycle / Recharge, this section, and ob serve all refrigerant and oil handling instructions.
Sy
mptom
Possib
le Sources
Acti
on
Insuffi

cient
cooling
Compre
ssor clutch slipping
*
R
enew clutch assembly
*
Fl
aps or vents closed / seized
*
Check f
ault codes #41 to 46
*
Bl
ower circuit fault
*
R
efer to PDU
*
Bl
ocked condenser matrix / fins
*
Check hig
h / low side pr
essures / renew. Check /
clean fins
*
Bl
ocked evaporator matrix
*
Check hig
h / low side
pressures / renew
*
Bl
ocked pollen filter (if fitted)
*
Cle
an or renew
*
Evaporator temp
erat
ure sensor faulty
*
R
efer to PDU
*
P
artial loss of refrigerant caused by leaking joint

or pipe
*
R
epair / renew
*
Blocked expan
sion valve
*
Check hig
h / low side
pressures / renew
*
Expans
ion valve fault
*
Chec
k system pres
sure differential
*
C
ollapsed air conditioning hose hose
*
Check hig
h / low side
pressures / renew
*
Moi
sture or air in the system
*
Chec
k system pressures
*
Low r
efrigerant charge
*
Initiate recovery
procedure, check fault code #23
*
Coo
lant flow valve open
*
Chec
k operation
*
Sy
mptom
Possib
le Sources
Acti
on
Int

ermittent cooling
Compre
ssor clutch slipping
*
R
enew clutch assembly
*
Compressor cl
utch circuit faulty
Blower(s) circuit faulty
*
*
R
efer to PDU
*
Motorized in-car aspirator faulty

*
R
efer to PDU, check fault code #11
*
Evaporator temp
erature sensor faulty

*
R
efer to PDU, check fault code #13
*
Bl
ocked condenser matrix / fins
*
Check hig
h / low side pressures / renew. Check / clean fins

*
Bl
ocked evaporator matrix
*
Check hig
h / low side
pressures / renew
*


Sym
ptom #1
Sy
mptom #1
Sy

mptom
Possib
le Sources
Acti
on

Climate Co
ntrol System - General In
formation - Air Conditioning (A/C)
System Check - Re tail Procedure
Gen
eral Procedures
E

vacuating the Manifold Gauge Set
Connecting the Manifold Gauge Set
C
AUTION: Only use hoses with connectors wh
ich are dedicated to HFC 134A charge ports.
Stabilizing the System

1.
At
tach the center (service) hose to a vacuum pump and start
the pump. Open fully both high and low valves and allow the
vacuum to remove air and mois ture from the manifold set for
at least five minutes.
CAUTION: It is imperative th at the vacuum pump is not
subjected to a positi ve pressure of any degree. Therefore the
pump must be fitted wi th an isolation valve at the center (service
hose) connection and this valve mu st be closed before the pump
is switched off. This operation replaces the 'purge' procedure used
on previous systems. Observe the manufacturer's
recommendation with regard to vacuum pump oil changes.
Turn the vacuum pump off and isol ate it from the center service
hose but do not open the hose to atmosphere.
1. Att
achment of the hose quick release connectors to the high
and low side system ports is stra ightforward, provided that the
high and low valves are closed and the system is NOT
operational.
WARNING: UNDER NO CIRCUMSTANCES SHOULD THE
CONNECTIONS BE MADE WITH THE SYSTEM IN OPERATION OR
THE VALVES OPEN. SHOULD THE VALVES BE OPEN AND A
VACUUM PUMP OR REFRIGERANT CONTAINER ATTACHED, AN
EXPLOSION COULD OCCUR AS A RESULT OF HIGH PRESSURE
REFRIGERANT BEING FORCED BACK INTO THE VACUUM PUMP OR
CONTAINER.
Assessment of system operating efficiency and fault
classification may be achieved by using the facilities on your
Recovery / Recharging / Recycling station, follow the
manufacturer's instructions implicitly and observe all safety
considerations.
1. Accurate test gauge data wi
ll on
ly be attained if the system
temperatures and pressures are stabilized.
E
nsure that equipment and hoses cannot come into
contact with engine moving parts or sources of heat.
It is recommended th at a free standing air
mover is placed
in front of the vehicle to provide air flow through the
condenser / cooling system.
St
art the engine, allow it to attain normal working
temperature and set at fast idle (typically 1200 to 1500
rpm).


Select full

air condit
ioning performance.
With
all temperatures and pres
sures stable, or displaying
symptoms of faults; begin relevant test procedures.

Parts List
The heater circuit 'scavenges' coolant from the engine cooling system by mean s of an electric water pump. The water pump
has a protection circuit to inhibit operation when the coolant temperature is <16°C; this is to prevent possible damage to
the impeller due to the presence of coolant borne ice particles. Coolant is drawn from the en gine system through the water
valve inlet port into the heater matrix. The coolant passes thro ugh the bottom section of the heater matrix from left to right
filling the end tank of the matrix before returning through the top half of the ma trix and through the outlet ports of the
water valve and back into the engine cooling system.
Non return valves are located in the heat er bypass hose and the hose between the water pump and valve. These valves are
required to prevent coolant flowing in th e wrong direction at low engine speeds and restrict convected flow through the
heater after the engine is switched off.
When the exterior ambient temperature is > 0°C the refrigerat ion system automatically operates cooling and dehumidifying
incoming air before it is re -heated by the heater matrix.
Water Valve Assembly
Location
The water valve assembly is located above the water pump, in the engine compartmen t and is secured to the firewall by a
bracket. The valve operates by means of an electrical solenoid which oscillates the valve stem between the inlet and outlet
ports.
When in automatic mode, the water valve duty cycle is influenced by the following inputs to the A/CCM:
Outlet air temperature 'Air off' heater matrix temperature External ambient Coolant temperature
ItemPart NumberDescription
1—Assembly pump - water
2—Hose - from header tank
3—Hose / connector - return to engine
4—Hose - heater feed to matrix
5—Valve - non return (by-pass)
6—Hose / connector - feed from engine
7—Hose - heater return from matrix
8—Assembly valve - water
9—Valve - non return

Engine speed (valve closed with the engine not running) Demand (set) temperature In-car temperature sensor Solar sensor
Re-heating of the refrigerated air is contro lled by the time that the water valve is open (i.e. not energised) over a six secon d
interval. The duty cycle of the water valve, the time open / time closed, is controlled by the A/CCM.
Maximum heating demand will cause the water valve to be fu lly open (not energised) to allow maximum coolant flow
through the heater matrix.
At Maximum cooling, the water va lve will be fully closed (energised) to prevent hot (engine temperature) coolant entering
the heater circuit; the pump however will continue to circulate coolant through both the heater matrix and water valve
bypass.
The water valve defaults open when the ignition is OFF.
Under engine stall conditions, when ignition is ON, the water valve will be open.
Water Pump Assembly
Located in the same area as the water valve, the water pump continually circulates coolant through the heater matrix
except when the conditions below apply:
The engine coolant is below 16°C. The ignition is OFF. Under engine stall conditions, when ignition is ON. Control panel OFF
Non return valves
The heater bypass hose has a non-return valve, located between the engine feed and return hoses. The valve prevents the
water pump from recirculating coolant fro m the heater at low engine speeds.
The flow indicator arrow embossed on the valve bo dy MUST point towards the coolant header tank.
CAUTION: Coolant flow will be compromi sed if either valve is fitted incorrectly. Observe the correct direction.
A second non-return valve is located betw een the water pump and water valve. This valve prevents hot coolant from flowing
into the heater with the engine switched off. The flow indicator arrow MUST point towards the water pump.
Heater feed and return hoses
The heater feed and return hoses are connected to the engine feed and return hoses by 'Quick-Fit' connection unions. The
feed hose has a Norma R20 connector and the return hose a Norma push and seal connector. The coolant system bleed
joints have Cobra clamps. All remaining hose connections have spring band hose clamps.
The engine feed hose is connected to the engine bypass hous ing and the engine return hose is connected to the engine
water pump.
Clamp Identification

19. Reconnect air conditioning pipes at the evaporator.
Remove blanking plugs.
Install, fully seat and lubr icate new O-ring seals.
Install bolts.
20. Install instrument pane l; refer to 76.46.01.
21. Recharge air conditioning system; refer to 82.30.30.
22. Re-fill cooling system; refer to 26.10.01 or (SC) 26.10.01.
23. Reconnect battery ground cable (IMPORTANT, see SRO
86.15.15 for further information).

15. Remove the temporary wooden support strut and reconnect
gas struts to the hood.
16. Check transmission fluid level an d top up as required; refer to
307A-01 (N/A) or 307B-01 (S/C), operation 44.24.02.
17. Refill the cooling system; refer to 26.10.01 or (SC) 26.10.01.
18. Recharge air conditioning system; refer to 82.30.30.
19. Reconnect battery ground cable (IMPORTANT, see SRO
86.15.15 for further information).

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