1994 JAGUAR XJ6 cooling

Climate Control Systems
14.4 TEMPERATURE CONTROL
14.4.1 Coolant Circuit
The main coolant system supplies liquid at engine temperature to the heater matrix to provide heat to the vehicle
interior. Unlike previous air blend / constant matrix temperature systems, in-car temperature is now controlled by
mixing recirculated coolant in the heater circuit with engine-temperature coolant. Matrix temperature is controlled
by a valve which opens to raise temperature (admit engine coolant) and closes to reduce it (recirculates coolant within
the circuit). The coolant flow valve operates on a six (6) second 'duty cycle', during which it may be open for whatever
period thecontrol system dictates. FACEvent airtemperature of howeveriscontrolled bythe'cool air by-passdamper'
which allows incoming air to flow around the top of the the heater matrix and thus remain unheated.
Because the engine coolant pump is driven proportionally to engine speed, the coolant delivery rate changes with
engine revolutions thus causing temperature variations. To stabilize the flow through the matrix, and thus the
temperature, an electrically driven circulation pump has been introduced into the system.
1
1. Engine 2. Coolant flow valve 3. Circulation pump
4. Heater matrix
5. Bottom hose
6. Engine cooling system radiator
Fig.
1 Coolant circuit, schematic view
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Climate Control Systems
14.8 REFRIGERATION CYCLE:
The Compressor draws low pressure, low temperature re- frigerant from the evaporator and by compression, raises re- frigerant temperature and pressure. High pressure, hot
vaporized refrigerant enters the Condenser where it is
cooled by the flow of ambient air.
A change of state occurs
as the refrigerant cools in the condenser and it becomes a
reduced temperature high pressure liquid.
From the condenser the
liquid passes into the Receiver / Drier which has three functions,
a) Storage vessel for varying system refrigerant demand.
b) Filter to remove system contaminants. c) Moisture removal via the dessicant.
With the passage through the
receiver/drier completed the,
still high pressure liquid refrigerant enters the Expansion
Valve where it is metered through a controlled orifice which
has the effect of reducing the pressure and temperature.
The refrigerant, now
in a cold atomized state, flows into the
evaporator and cools the air which is passing through the
matrix.
As heat is absorbed by the refrigerant
it once again changes
state, into a vapour, and returns to the compressor for the
cycle to be repeated (Fig.
1).
There is an automatic safety valve incorporated in the com- pressor which will operate should the system pressure be in
excess of 41 bar. The valve will reseat when the pressure
drops below 27,6 bar.
W Thedivisionof HIGHandLOWsideissimplythesys- tem pressure differential created by the compressor
discharge (pressure), suction (inlet) ports and the
relative inlet and outlet ports
ofthe expansion valve.
This differential is critical to system fault diagnosis
and efficiency checks.
Twelve Cylinder Vehicles only:
Dual pressure switch: This two-function pressure switch
cuts electrical power to the compressor clutch if the system
pressure is outside of the range
of 2 Bar (1st Function) to 30
Bar (2nd Function).
Six Cylinder Vehicles only:
There are two switches incorporated into the high side of the
system which have the following functions:
a) Trinary; This three function pressure switch, cuts electri
-
cal power to the compressor clutch should the system pres- sure not be in a range of 2 bar (1st function) to 30 bar (2nd
function). The switch also provides a ground signal to oper
- ate the appropriate relay (within the 'Stribel,' unit) to ener- gize both engine cooling fans when maximum A/ C cooling
is required. Operation pressure, 20 bar input (3rd function).
b) Pressure Switch Slow Cooling Fans; When the system
pressure is 12 bar, medium A/ C demand, the operation of
this switch connects both engine cooling fans in series to op- erate at half battery voltage and so, half fan speed. 1.
Compressor
2. Condenser
3. Receiver / Drier 4. Expansion Valve
5. Evaporator
6. Pressure switch - Dual type
on 12
cyl & Trinary on 6 cyl
Fig. 1
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Climate Control Systems
14.10 FAULT DIAGNOSIS
14.10.1 Introduction
It is very important to positively identifythe area of concern before starting a rectification procedure. A little time spent
with your customer to identify the conditions under which a problem occurs will be beneficial. Relevant criteria are:
Weather conditions, ambient temperature, intermittent or continuous fault, airflow fault, temperature control fault, dis
- tribution fault and air inlet problem.
14.10.2 Functional Check
This simple 'first line check' will allow you to ascertain whether the system is operating within its design parameters,
without recourse to (JDE). Please carry out the following, in order.
0 Start engine and attain normal running temperature.
0 Presss AUTO to display selected temperature and illuminate AUTO & AJC state lamps.
0 Rotate FAN to increase or decrease lower speed, verify bar graph representation.
0 Operate AJC to toggle on or off. Because the compressor can be inhibited by the engine management system,
ensure that the engine temperature is normal and that the ambient is above 5O C.
0 Operate RECIRC, state lamp should be lit and the flap behind the blower grille open.
0 Operate distribution buttons in turn, verify correct air distribution and relevant state lamp.
0 Operate DEFROST, check max fans and air to front screen.
0 Cycle TEMPERATURE to 'Hi' and 'Lo' to verify demanded variations and display operation. Note that extremes
will provide max heat or cold independent of in-car temperature.
0 Operate EX to toggle between ambient and control temperatures.
0 Operate HFS and HRW to note timer and mirror operation.
0 Initiate System Self Test to check for, and extract, stored faults should any of the above not perform as stated.
14.10.3 System symptoms
There are five basic symptoms associated with air conditioning fault diagnosis. The following conditions are not in order of priority.
No Cooling
0 Is the electrical circuit to the compressor clutch functional?
0 Is the electrical circuit to the blower motor(s) functional?
0 Slack or broken compressor drive belt.
0 Compressor partially or completely seized.
0 Compressor shaft seal leak.
0 Compressor valve or piston damage (may be indicated by small variation between HIGH &LOW side pressures
relative to engine speed).
0 Broken refrigerant pipe (causing total loss of refrigerant).
0 Leak in system (causing total loss of refrigerant) - possible code 23.
0 Blocked filter in the receiver drier.
0 Evaporator sensor disconnected - possible code 13.
0 Pressure switch faulty - possible code 23.
X300 VSM Issue 1 August 1994

Climate Control Systems
lnsufficent Cooling
0 Sluggish blower motor(s).
0 Restricted blower inlet or outlet passage
0 Blocked or partially restricted condenser matrix or fins.
0 Blocked or partially restricted evaporator matrix.
0 Blocked or partially restricted filter in the receiver drier.
0 Blocked or partially restricted expansion valve.
0 Partially collapsed flexible pipe.
0 Expansion valve temperature sensor faulty (this sensor is integral with valve and is not serviceable).
0 Excessive moisture in the system.
0 Air in the system.
0 Low refrigerant charge - possible code 23.
0 Compressor clutch slipping.
0 Blower flaps or distribution vents closed or partially seized - possible codes 41 or 46.
0 Coolant flow valve not closed.
0 Evaporator sensor incorrectly positioned
m: Should a leakor low refrigerant be established as the cause of /NSUff/C/€NTCOOL/NG,followthe procedures
Recovery / Recycle / Recharge, this section, and observe all refrigerant and oil handling instructions.
lntermiffent Cooling
0 Is the electrical circuit to the compressor clutch consistent?
0 Is the electrical circuit to the blower motor(s) consistent?
0 Compressor clutch slipping?
0 Motorized in-car aspirator or evaporator temperature sensor faulty, causing temperature variations - possible
codes 11 or 13.
0 Blocked or partially restricted evaporator or condenser.
Noisy System
0 Loose or damaged compressor drive belt.
0 Loose or damaged compressor mountings.
0 Compressor oil level low, look for evidence of leakage.
0 Compressor damage caused by low oil level or internal debris.
0 Blower motor(s) noisy.
0 Excessive refrigerant charge, witnessed by vibration and 'thumping' in the high pressure line (may be indicated
by high HIGH & high LOW side pressures).
0 Low refrigerant charge causing 'hissing' at the expansion valve (may be indicated by low HIGH side pressure).
0 Excessive moisture in the system causing expansion valve noise.
0 Air-lock in water pump*.
lnsufficent Heating
0 Coolant flow valve stuck in the closed position.
0 Motorized in-car aspirator seized.
0 Cool air by-pass damper stuck or seized - possible code 43.
0 Blocked or restricted blower inlet or outlet.
0 Low coolant level.
0 Blower fan speed low.
0 Coolant thermostat faulty or seized open.
0 Water pump inoperative or blocked
0 Air-lock in matrix*.
m: * Please see Sections 4.1 and 4.2 for specific coolant fill / bleed procedures.
Electrical faults may be more rapidly traced using
(JDE), please refer to the (EDM).
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Climate Control Systems
14.13 SYSTEM CHECKING WITH MANIFOLD GAUGE Sm
14.13.1 Evacuating the Manifold Gauge Set
Attach the centre (service) hose to a vacuum pump and start the pump. Open fully both high anddow valves and allow
the vacuum to remove air and moisture from the manifold set for at least five minutes.
Turn the vacuum pump off and isolate it from the centre service hose but do not open the hose to atmosphere.
CAUTION: It is imperative that the vacuum pump is not subjected to a positive pressure of any degree. Therefore
the pump must be frtted with an isolation valve at the centre (service hose) connection and this valve
must be closed before the pump is switched off. This operation replaces the 'purge' procedure used on
previous systems. Observe the manufacturefs recommendation with regard to vacuum pump oil
changes.
14.13.2 Connecting the Manifold Gauge Set
CAUTION: Only use hoses with connectors which are dedicated to HFC 134A charge ports.
Attachment of the hose quick release connectors to the high and low side system ports is straightfotward, provided
that the high and low valves are closed and the system is NOT operational.
Assessment of system operating efficiency and fault classification may be achieved by using the facilities on your
Re- covery / Recharging / Recycling station, follow the manufacturers instructions implicitly and observe all safety con- siderations.
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.
14.13.3 Stabilizing the System
Accurate test gauge data will only be attained if the system temperatures and pressures are stabilized.
Ensure that equipment and hoses cannot come into contact with engine moving parts or sources of heat.
It is recommended that a free standing air mover is placed in front of the vehicle to provide air flow through the con- denser / cooling system, see illustration below.
Start the engine, allow
it to attain normal working temperature and set at fast idle (typically 1200 to 1500 rpm). Select full air conditioning performance.
With all temperatures and pressures stable, or displaying symptoms of faults; begin relevant test procedures.
Fig.
1
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Climate Control Systems
High Side Gauge
Normal
@ 14.16 SYSTEM PRESSURE FAULT CLASSIFICATION
This table should be used in conjunction with the graphical representations of 'High side' pressure / ambient tempera- ture and 'Low side' pressure / evaporator temperature, this section.
Fault Cause
Discharge air initially cool then Moisture in system
warms up
1 Low Normal
Low
Low
Low
Low
I Low
As above As above
Discharge air slightly cool HFC
134A charge
low
Discharge air warm HFC
134A charge very low
Discharge air slightly cool or frost Expansion valve
stuck closed
build up
at expansion valve
Discharge air slightly cool, sweat
- Restriction in High side of
ing or frost
after point of restriction system
I
Low
High
High
I
Compressor noisy Defective compressor
reed valve
Discharge air warm and high side HFC
134A charge
high or
pipes hot inefficient
condenser cooling
dueto
air flow blockage or engine cooling
fans not working
Expansion valve stuck open
Discharge air warm
Sweating or frost
at evaporator
If erratic or unusual gauge movements occur, check the equipment against a known (calibrated) manifold
gauge
set. ~ ~~~
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15.1.13 Spillage and Leakage
If material is spilled or released,contact Jaguar Service for clean up procedures. All other personnel must be kept away
from contaminated area.
Do not dispose contaminated propellant or water into storm or sanitary sewers, ground water or soil.
Spills may be reportable to local state,
and/or federal authorities.
Material should
be disposed of by incineration or chemical oxidation under carefully controlled conditions by specially
trained individuals in accordance with local State and Federal regulations.
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15.1.14 Scrapping Vehicles With Live Airbag(s)
When scrapping a vehicle with a live airbag, first deploy the
airbag in accordance with following procedures. This
procedure assumes airbag wiring is undamaged.
See Handling
/ Safety information.
If the airbag is
to be removed see Airbag Modules Assembly/ Removal/Service Instructions.
Equipment required: Insulation Displacement Connectors
(IDC) (Scotchloks) (two-off), battery, two-off ten meter
lengths of lmm2 wire fitted with crocodile clips at one end. (See Fig. 1).
WARNING: THE DEPLOYMENT PROCEDURE SHOULD BE PERFORMED OUTDOORS AWAY FROM OTHER
PERSONNEL.
Remove any loose debrisfrom around airbag and ensure no
flammable liquids are present.
Disconnect the vehicle battery. Fig. 1
Link harness conn&ion & deployment method
WARNING:
ALWAYS CONNECT TO AlRBAG FIRST, AS THE BAG WILL DEPLOY IMMEDIATELY ON CONNECTION TO
THE BATTERY.
Remove passenger side and driver side under-scuttles / knee bolster.
. Disconnect the airbag connector under the facia.
. Look for the yellow harness connectors and cut the wires originating from the airbag just above the mating plug.
w: The harness connected between the driver's airbag and the yellow connector has one red/purple feed wire and
one pinkbrown return wire.
The harness connected between the passenger's airbag and the yellow connector has two
red/purple feed
wires and one pinwpurple return wire.
Pass a 10 meter (33ft) link harness containing two lmm2 wires through the window aperture, and connect using an
. Close all doors, leave window with lead open.
. Ensure no personnel are in the car or in the area around the car.
. Move back 10 meters (33ft) and connect harness crocodile clips to battery: the airbag will immediately deploy.
Allow the unit to cool for at least 20 minutes. Cooling modules should be continuously monitored to ensure heat
(continued next page)
Insulation Displacement Connector (IDC) and two crocodile clips, to the airbag wires.
generated does not create
a fire with spilled liquids or other debris.
X300 VSM 5 Issue 1 August 1994

Snecif icat ion W -I- ..........
e
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CON TENTS
Title Page
Specification. 1995 Model Year Vehicles ................................................................... 1
EngineManagementSystem ........................................................................\
. 1
Cooling System ........................................................................\
............ 7
Fuelsystem Pump ........................................................................\
......... 7
Clutch ........................................................................\
................... 7
Manual Transmission Ratios ........................................................................\
. 1
Automatic Transmission Ratios ....................................................................... \
2
Final Drive Unit Ratios ........................................................................\
..... 2
Climate Control System ........................................................................\
..... 2
Braking System ........................................................................\
............ 3
Steering&Suspension ........................................................................\
...... 4
Electrical Equipment ........................................................................\
....... 5
Lubricants & Fluids ........................................................................\
......... 7
Vehicle Weights ........................................................................\
........... 9
Tires ........................................................................\
.................... 10
Snowchains ........................................................................\
............. 17
Bulbs ........................................................................\
................... 12
Fuses ........................................................................\
................... 14
Issue 1 August 1994 AI-95MY i X300 VSM