climate control system JAGUAR XJ6 1994 2.G Owner's Manual

Climate Control Systems
8. AUTO selection display.
9. EXTERIOR temperature selection button. There are two modes:
a) Press and immediate release; provides timed display of four (4) seconds.
b) Press and hold for two (2) seconds; 'latches' the mode until operator over-ride.
10. A/C push-on / push-off button will either engage or disengage (as indicated by the state lamp) the refrigeration
system compressor. The state lamp is also used as a compressor speed fault indicator,see System protection, this
section.
11. AUTO push-on button and state lamp. When selected and the state lamp lit, the A/C mode is selected and control
of demand temperature, fans speed, and air distribution is automatic. AUTO is cancelled by selection of any 'dis- tribution' button, A/C off, or manual FANS SPEED.
12. DEFROST push
-on / push-off button and state lamp. When engaged, air is distributed to the screen at maximum
fans speed and the heated front screen elements (where fitted) are ener ized. The heated front screen is automati- cally timed for a six (6) minute cycle but may be cancelled by pressing tfe HEATED FRONT SCREEN button. Auto- matic temperature control is retained and the fans speed may be manually reduced. Deselection will return the
system to the previous state and selection of AUTO will resume automatic system control.
13. The push
-on / push-off (F) button with state lamp manually controls the HEATED FRONT SCREEN (where fitted).
This facility allows rapid screen de-icing using laminated electrical heating elements to supplement the hot air
defrost.
14. The push-on / push-off (R) button with state lamp manually controls the HEATED REAR SCREEN and door mirror
glass heating elements for a timed cycle of; screen twenty (20) minutes and mirrors eleven (1 1) minutes.
m: The state lamp will remain lit after the mirror timer has gone through its 11 minute cycle and will not go out
until either completion of the 20 minute screen cycle or manual override.
15. TEMPERATURE decrease button
in IoC or I0F steps.
16. TEMPERATURE increase button in
IoC or I0F steps.
w: Automatic temperature control operates over the range 17OC to 31OC (61OF to 90OF). Extreme limits selected
by items 15 and 16 ('Lo' and 'Hi') provide maximum cooling or heating at maximum fans speed.
17. FACE level manual distribution over
-ride push-on / push-off button and state lamp.
0 18. Bi LEVEL (foot and face) manual distribution over-ride push-on / push-off button and state lamp.
19. FOOT level manual distribution over
-ride push-on / push-off button and state lamp.
20. DEMIST (screen and foot) level manual distribution over
-ride push-on / push-off button and state lamp.
!Y&Q: Selection of AUTO will over-ride any manual setting and deselection of any manual distribution will revertthe
system to AUTO distribution.
21. FACE VENTTEMPERATURE CONTROL thumb
-wheel. Situated between dash centre face level vents to reduce face
air outlet temperature relative to that of the foot-well.
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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
Manual Inputs
Automatic inputs
outputs
14.5 AIR CONDITIONING CONTROL MODULE (A/CCM)
14.5.1 Description
Theclimate control system peripheralscommunicate with theA/CCMvia three main devicecategories, plusthevehicle
power supply and ground connections.
Control panel Face Vent Temperature Control
Temperature and solar sensors
Flap
servo motor potentiometers
Circulation pump
& coolant flow valve
Power
transistor(fan speed control)
Compressor lock sensor
(12 cylinder only)
Instrument pack (coolant temp
& road speed) (engine revolutions via engine control module)
Blower motors (Left
& Right) & associated relays
Flap
servo motors
Heated front
/ rear screens & exterior mirror relays
Motorized in
-car aspirator
Compressor clutch request to engine control module (not
heater-only cars)
Circulation pump relay
Coolant flow valve
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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
0
Climate Control Systems &j%
\d J82-697
Fig. 1
k9 J82-498
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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
0
0
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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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