JAGUAR XJ6 1994 2.G Workshop Manual

Climate Control Systems
. Centre vent flap
Foot flap
Defrost flap
I I
14.5.2 Control Module Interfaces
. Recirculation switch
. Air con onloff switch
. System onloff switch
. Auto. / Man. select
. Set temperature
. Air flow outlet mode set
. Heated front screen switch
. Heated rear screen &
. External temp. display
. FahrenheiVCentigrade
heated mirror switch
switch
switches
. Solar sensor
. Motorized in-car aspirator
. Ambient temp. sensor
9 Evaporator temp. sensor
. Heater matrix temp. sensor
. Compressor lock sensor
. Face differential temp. control
. Refrigerant pressure switch
. Engine speed signal
. Engine coolant temperature
Vehicle speed signal
Circulation pump
. Coolant flow valve
. Power transistor (fan speed
= Servo motor potentiometers:
signal
control)
LH air inlet flap
RH air inlet flap
Centre vent flap
Foot flap
Defrost flap
Air by
-pass flap
CONTROL PANEL
4
-
4
4
4
4
4
4
A 1 CCM
e I . External temp. display
. Coolant recirculation valve
. Coolant recirculation pump
Cool air by-pass
Air Flow Speed Control
. LH blower motor & power transistor
. RH blower motor & power transistor
. LH high speed relay
. RH high speed relay
. LH air inlet
. RH air inlet
. Compressor
- . Front screen heater (to EMS)
- . Heated rear screen
and door mirrors
Fig.
1 Schematic view AI CCM Inputs & Outputs
0
0
0
0
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Climate Control Systems
CONTROL MODULE FAULT & CONDITION SELF-ANALYSIS
0 14.6 14.6.1 System Health
The climate control system has a 'self-test' facility, accessible from the control panel. The self test sequence has two
basic modes:
0 System error information is stored in the A/CCM up to a maximum of five faults. Should a fault occur there will
be an audible 'beep' and the message 'Er' will be displayed on the control panel LCD for approximately five (5)
seconds after ignition on. Please note that this will happen only once in any ignition switch cycle. The error
source may be accessed by the procedure described in 'Self Test System Diagnosis', this section.
0 Panel communication check may be initiated by following the instruction in 'Self Test System Diagnosis', this
section.
Nsfe: Displayed error codes are NOT directly related to Jaguar Diagnostic Equipment (JDE) but more detailed fault
related information may be accessed using Portable Diagnostic Unit (PDU).
14.6.2 System Protection
Power to the compressor clutch may be cut should either the engine management or air conditioning control systems
detect certain conditions; these conditions may be caused by Fault or Demand and can be classified thus:
0 Engine coolant overheat,
0 Refrigerant excessive pressure.
0 Refrigerant, insufficient pressure or low charge weight.
0 Speed differential between compressor and crankshaft caused by belt slippage or compressor seizure (indi-
cated by A/C state lamp flashing once per second) - 12 cylinder engine only. This feature, 'lock sensing' is fully
explained
in the EDM.
Demand
0 Engine maximum power requirement
0 Electrical system drain at engine idle.
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Climate Control Systems
14.7 AIR DlSTRlBUTlON
(Refer to illustrations on this and next page)
Air is drawn from the plenum chamber into the heater/cooler case at the lower front right and left hand sides. All air must first pass through the evaporator (not fitted to heater only cars) and then through the heater matrix for in-car distribution.
When cooler air than that available from the other outlets is desired at the FACE vents, air by
-passes the matrix via
the 'cool air by-pass damper' within the range cold to hot.
The flaps for FOOT, COOL AIR, CENTRE VENT, RH & LH RECIRCULATION and DEFROST are electrically driven by indi- vidual motor / potentiometer units.
1. Face outlet
2. Defrost outlet
3. End-of-dash outlet 4. Cool air by-pass damper
5. Evaporator
6. Air in 7. Foot outlet (front)
8. Foot outlet (rear)
9. Rear face outlet 10. Heater matrix
J82-49L
Fig. 1
\d J82-495 \d J82-L96
(Solid arrow = Hot, Line arrow = Cold)
Fig. 2
0
0
0
0
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0
0
Climate Control Systems &j%
\d J82-697
Fig. 1
k9 J82-498
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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
0 14.9 GENERAL SYSTEM PROCEDURES
14.9.1 Leak Test
Faults associated with low refrigerant charge weight and low pressure may be caused by leakage. Leaks traced to
mechanical connections may be caused by torque relaxation or joint face contamination. Evidence of oil around such
areas is an indicator of leakage. When checking for non visible leaks use only
a dedicated HFC 134A electronic analyzer
and apply the probe all round the joint / connection.
Should a leak betraced to a joint,checkthatthefixing issecuredtothecorrecttightening torque before any other action
is taken.
Do not forget to check the compressor shaft seal and evaporator.
CAUTION : Never use a dedicated CFC 12 or naked flame type analyzer.
14.9.2 Charge Recovery (System depressurization)
The process of HFC 134A recovery will depend on the basic characteristics of your chosen recovery/ recycle I recharge
equipment, therefore, follow the manufacturer's instructions carefully.
Remember that compressor oil may be drawn
out of the system by this process, take note of the quantity recovered
so that it may be replaced.
CAUTION: Observe all relevant safety requirements.
Wear suitable eye and skin protection
Do not mix HFC 134A with CFC 12. Do not vent refrigerant directly to atmosphere and always use Jaguar approved recovery I recycle I re- charge equipment.
Take note of the amount of recovered refrigerant, it will indicate the state of the system. 0
14.9.3 Evacuating the System
This process, the removal of unwanted air and moisture, is critical to the correct operation of the air conditioning sys-
tem. The specific procedures will vary depending on the individual characteristics of your chosen recovery I recycle / recharge equipment and must be carried out exactly in accordance with the manufacturers instructions. However,
it is recommended that the initially only the HIGH side valve be opened at the start of the procedure. After a short time a small depression should be seen on the LOW side, at which point the LOW side valve may be opened and the evacu- ation process completed. If a vacuum is not registered on the LOW side it may indicate that the expansion valve is
jammed closed or that the system is blocked. This simple check may save time and effort when the system is re- charged.
Moisture can be highly destructive and may cause internal blockages due to freezing, but more importantly, water sus- pended in the PAG oil will damage the compressor. Once the system has been opened for repairs, or the refrigerant
charge recovered, all traces of moisture MUST be removed before recharging.
14.9.4
The amount of oil drawn out during a recovery procedure will be dependent on the state of the system and the rate
of recovery. The quantity will be approximately 30 to 40 ml; this may vary, and the figure is given only for guidance.
The oil separator vessel in the recovery equipment must be clean and empty
at the start of the process so that the quan- tity of oil which is drawn out may be accurately measured.
Oil may be added by three methods,
1 and 2 being direct into the system and 3 with the compressor off the vehicle;
1. Via the recovery I recycle 1 recharge station.
2. Proprietary oil injector.
Adding Lubricating Oil - Compressor Related
1ynfa: Equipment manufacturer's instructions must be adhered to when using direct oil introduction.
3. Directly into the original, or new unit, because of rectification work to the existing compressor, or the need to fit a new compressor.
Original
From an existing compressor, drain the oil into a measuring cylinder and record the amount. Flush the unit out
with fresh PAG oil and drain thoroughly, Replenish the compressor with the same amount of PAG oil that was
originally drained out and immediately plug all orifices ready for refitting to the vehicle.
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Climate Control Systems
New
Drain and discard the transit lubricating oil from a new compressor before it is be fitted. An adjustment must
then be made to avoid over-filling the system, by taking into account;
a) the quantity found in the original compressor.
b) the quantity deposited in the recovery equipment oil separator from the charge recovery operation.
Drained from original compressor
50 ml
Recovered from oil separator 40 ml
Quantity to be put in new compressor 50 + 40 = 90 ml
Typical example:
Please note that the discrepancy between the cumulative figure of recovered and drained oil and the nominal capacity
of
180 ml is caused by normally unrecoverable oil being trapped in components such as the condenser, receiver/ drier
or evaporator.
The previous statements apply even
if a problem has occurred due to oil leakage. The amount of oil lost due to leakage
is generally small, so to avoid over-filling please follow the example.
If however the recovery process has not been necessary because refrigerant has also been lost, then ONLY replace the
quantity drained from the original compressor.
14.9.5
Should a major component such as condenser, receiver / drier or evaporator be renewed then an adjustment to the
system oil level must be made. This may be carried out in the same way as the examples for the compressor except
for the fact that trapped oil within any one of these components cannot normally be drained. Therefore, a nominal
amount of oil should be substituted
in addition to that recovered from the recovery station separator.
Adding Lubricating Oil - Component Related
Condenser Add 40 ml
Evaporator Add 40 ml
Receiver / drier NO adjustment
CAUTION: Always decant fresh oil from a sealed container and do not leave oil exposed to the atmosphere. PAG
oil is very hygroscopic (absoh water) and will rapidly attract atmospheric moisture.
PAG oil must NEVER be mixed with mineral based oils.
Do not re-use oil following a recovery cycle, dispose of it safely.
14.9.6 Adding Refrigerant
In order that the air conditioning system may operate efficiently it must contain a full refrigerant charge. The indica- tions of some system defects, and the results of certain tests, will show that a low charge is the most probable cause
of the fault. In such cases the charge should be recovered from the system, the weight noted, and the correct amount
installed.
Should refrigerant be added in liquid form, initial engine start
-up revolutions must NOT exceed 2000 RPM for a period
of (2) two minutes. If the engine speed is excessive, compressor damage may occur due to the lubricating oil and the
liquid refrigerant being initiallyforced around the system as a 'slug', thus taking oil awayfrom the compressor. These
marginal lubrication conditions in the compressor will cease as the refrigerant becomes gaseous.
Never attempt to 'guess' the amount of refrigerant in a system, always recover and recharge with the correct charge
weight; this is the only accurate method.
CAUTION: If oil was drawn out during the recovery process, the corM amount may be added directly from your
recovery / recycle /recharge station (if so equipped) prior to the 'charging process'. It must be stressed that the need to protect compressor oil from moisture is vital, observe the procedures
in HANDLING LUBRICATING OIL and those concerning excessive engine revolutions.
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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.
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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
Action
Simultaneously hold AUTO and RECIRC - Switch
ignition to ON
Press AUTO
Press FACE
Simultaneously press FACE and HRW
Press
RECIRC (Press FAN to skip actuator check)
Press FAN
14.11 SYSTEM SE1 F-TEST
14.11. I Interrogation Procedure via the Control Panel
Result
Display element check
Any stored fault NUMERIC code
(If ZERO appears there are
no stored codes)
Scroll through stored faults (maximum of
5)
Clear stored fault codes (may need to be repeated for each
fault)
Initiate actuator check (Actuator codes
20 through 27*)
Exit error check mode
Fault Code
0
11
12
13
14
15
21
22
0
23
14.1 1.2 Control Panel Fault Code Key
Item Description
Normal Operation No
fault codes present, wait 30 seconds for system self-
check.
Motorized In
-car Aspirator Open /short in sensor circuit. Panel fault codes are not stored
for motorized in
-car aspirator motor failure.
Ambient Temperature Sensor Open
/ short circuits.
Evaporator Temperature Sensor Open
/ short circuits.
Water Temperature Input Instrument pack output.
Heater Matrix Temperature Sensor Open
/ short circuits.
Solar Sensor Open
/ short circuits.
Compressor Lock Signal
- 12 cylin- Open /short circuits. Low gas charge, low compressor oil,
der and supercharged
6 cylinder loose belt.
engines only.
Refrigerant Pressure Switch Open /short circuits. Low gas charge*
31
32
33
34
35
36 0
I 24 1 Face Vent Demand Potentiometer. 1 Open / short circuits
LH Fresh
/ Recirc. Potentiometer
RH Fresh / Recirc. Potentiometer
cool ~i~ by-pass potentiometer
Defrost Vent Potentiometer
Centre Vent Potentiometer
Foot Vent Potentiometer Open
/short circuit
in potentiometer. feed.
w: and log further faults. Cycling the ignition two or three times
after rectification of the fault will cure this.
In certain circumstances, the motor can over-travel
43
44
I Defrost Vent Motor
I Cool Air by-pass Motor
I 41 I LH Fresh / Recirc. Motor I
Check for short / open circuits in motor drive lines. Motor flap
sticking
/ jammed.
1 42 I RH Fresh / Recirc. Motor I
1 45 I Centre Vent Motor I
46 I Foot Vent Motor
w: In ambient temperatures below Oo C, the system may log fault code 23 because the low ambient causes a tem-
porary low gas pressure. Where the ambient temperature rise above 40" C, and if the engine is close to over- heating, feed to the compressor clutch may be cut and code 23 registered.*
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