air conditioning LAND ROVER DISCOVERY 1995 Repair Manual

AIR CONDITIONING
5
DESCRIPTION AND OPERATION Condenser cooling fans
The condenser cooling fans operate automatically
whenever the air conditioning system is switched on.
Fan timer unit
The thermostatically controlled timer will continue to
operate the cooling fans after the air conditioning or
ignition is switched off. When the system temperature
is excessive, the fans will operate for 10 minutes to
reduce condenser and underbonnet temperature.
Blower control
The blower can be operated at any one of four speeds
by sliding the blower switch to the required position.
When the blower is switched off the air conditioning
system will not operate.
The fresh air/recirculation flaps can move between
two positions. One position covers the outside air
inlet, leaving open an inlet from the inside of the
vehicle clear, when recirculated air is required. In the
other position they will cover the inlet from the inside
of the vehicle leaving open the outside air inlet when
fresh air is required.Heater distribution and blend unit control
Blower unit air flow, having passed through the
evaporator passes into the heater blend unit to be
heated, if required. It is then directed into the vehicle
interior in accordance with the flap positions
designated by the air distribution control. Heater flaps
control the amount of air flowing through the heater
matrix. These flaps are controlled individually by the
driver's and passenger's temperature controls.
When the temperature control is in the cold position, a
micro switch actuates a vacuum control to close the
coolant valve on the engine. As the temperature
control is moved away from cold, the coolant valve is
opened allowing heated engine coolant to flow
throught the heater matrix. The temperature of the
heated air flow into the vehicle interior is controlled by
the blend flaps.
The distribution control moves the flaps which control
the direction of the air flow into the interior of the
vehicle.

AIR CONDITIONING
1
FAULT DIAGNOSIS AIR CONDITIONING FAULTS
FAULT CAUSE REMEDY
1. Incorrect voltage. 1. Check voltage.
A.2. Open or defective fuse or relay. 2. Check and replace as necessary.
BLOWER3. Loose wire connection including 3. Check system wires; tighten
MOTORground. all connections.
INOPERATIVE4. Switch open or defective. 4. Replace switch.
OR SLOW5. Tight, worn, or burnt motor 5. Replace motor.
RUNNINGbearings.
6. Open rotor windings. 6. Replace motor.
7. Worn motor brushes. 7. Replace motor.
8. Shaft binding-blade misaligned. 8. Check alignment. Repair or replace
as necessary.
9. Defective resistors 9. Rectify or replace.
1. Incorrect voltage. 1. Check voltage.
2. Open or defective fuse or relay. 2. Check and replace as necessary.
B.3. Defective thermostat control or 3. Replace thermostat or
COMPRESSORpressure switch. pressure switch.
CLUTCH4. Shorted or open field coil. 4. Replace coil.
INOPERATIVE5. Bearing seized (clutch will not 5. Replace clutch pulley assembly.
disengage).
6. Refrigeration circuit problem causing
heavy load and excessive drive
torque.6. Check and rectify.
1. Incorrect alignment. 1. Check alignment; repair as
necessary.
2. Loose belt. 2. Adjust to proper tension.
C.3. Compressor not mounted securely. 3. Repair as necessary.
COMPRESSOR4. Bearing in clutch-pulley 4. Remove clutch and replace
CLUTCHassembly not pressed in. clutch pulley assembly.
NOISY5. Low voltage to clutch. 5. Check connections and voltage.
6. Clutch will not spin freely. 6. Refer to B5 above.
7. Oil on clutch face. 7. Check compressor seals for leaks.
8. Slipping clutch. 8. Refer to C5 above. Then check air
gap.
9. Overloaded or locked compressor. 9. Repair or replace compressor.
10. Icing. 10. Check for suction line frosting.
Replace expansion valve if
necessary.
Replace receiver/drier if necessary.
D.1. Motor and/or blades improperly 1. Check mountings, adjust as
CONDENSERmounted. necessary.
VIBRATION2. Foreign matter build-up on 2. Clean blades with a suitable
blades. non-inflammable cleaner.
3. Excessive wear of motor bearings. 3. Replace motor.

82AIR CONDITIONING
2
FAULT DIAGNOSIS REFRIGERATION SYSTEM FAULTS
For any refrigeration system to function properly all
components must be in good working order. The unit
cooling cycle and the relationship between air
discharge temperature and ambient temperature and
the pressures at the compressor can help to
determine proper operation of the system.
The length of any cooling cycle is determined by such
factors as ambient temperature and humidity,
thermostat setting, compressor speed and air leakage
into the cooled area, etc. With these factors constant,
any sudden increase in the length of the cooling cycle
would be indicative of abnormal operation of the air
conditioner.
The low and high side pressures at the compressor
will vary with changing ambient temperature, humidity,
in-car temperature and altitude.
The following items should be checked before
operating the system:
1.Compressor drive belt tension.
2.Compressor magnetic clutch operation.
3.Condenser fan operation.
4.Condenser fins, dirt will cause poor cooling and
higher operating temperatures.The following conditions should be checked after
operating the system for several minutes:
1.All high pressure lines and components should
be hot to the touch.
2.All low pressure lines should be cool to the
touch.
3.Inlet and outlet temperatures at the receiver/drier
should be at the same temperature (warm). Any
very noticeable temperature difference indicates
a blocked receiver/drier.
4.Heavy frost on the inlet to the expansion valve
may indicate a defective valve or moisture in the
system.
5.Evaporation air temperature will vary with
ambient temperature and humidity. As humidity
increases the outlet temperature will be higher.

AIR CONDITIONING
3
FAULT DIAGNOSIS FAULT CAUSE REMEDY
1. Overcharge of refrigerant. 1. Discharge, evacuate and charge
system.
A.
HIGH HEAD2. Air in system. 2. Discharge system, fit new drier,
PRESSUREevacuate and charge system.
3. Condenser air passage clogged 3. Clean condenser of debris.
with dirt or other foreign matter.
4. Condenser fan motor defective. 4. Replace motor.
5. Incorrect voltage to fan motor. 5. Check voltage.
1. Undercharge of refrigerant; 1. Evacuate and charge system.
B.evident by bubbles in sight Check for leakage.
LOW HEADglass while system is operating
PRESSURE2. Split compressor gasket or 2. Replace gasket and/or reed
leaking valves. valve. Fit new drier, evacuate and
charge system.
3. Defective compressor. 3. Repair or replace compressor.
1. Loose drive belt 1. Check belt tension.
2. Refrigerant flooding through
evaporator into suction line; evident
by ice on suction line and suction
service valve.2. Check thermobulb. Bulb should be
securely clamped to clean horizontal
section of copper suction pipe.
C.3. Expansion valve stuck open. 3. Replace expansion valve.
HIGH4. Leaking compressor valves, 4. Replace valves and/or
SUCTIONvalve gaskets and/or service gaskets. Fit new drier
PRESSUREvalves. evacuate and charge system.
5. Receiver/drier blocked; evident 5. Fit new drier, evacuate
by temperature difference and charge system.
between input and output lines.
1. Expansion valve thermobulb not 1. Warm thermobulb with hand.
operating. Suction should rise rapidly to 1.4 bar
20 lb/in
2or more. If not replace
expansion valve.
2. Expansion valve sticking closed. 2. Check inlet side screen.
D.Clean if clogged. Refer
LOWto C-2 and C-3.
SUCTION3. Moisture freezing in expansion valve
orifice. Valve outlet tube will frost
while inlet hose tube will have little or
no frost. System operates
periodically.3. Fit new drier, evacuate and charge
system.
4. Dust, paper scraps, or other debris
restricting evaporator blower grille4. Clean grilles as required.
5. Defective evaporator blower motor,
wiring, or blower switch.5. Refer to Fault Diagnosis Chart for
blower motor.

82AIR CONDITIONING
4
FAULT DIAGNOSISFAULT CAUSE REMEDY
E.
NOISY
EXPANSION
VALVE
(steady hissing)1. Low refrigerant charge; evident by
bubbles in sight glass.1. Leak test. Repair or replace
components as required.
F.1. Expansion valve not operating 1. Refer to C-2, C-3, D-1
INSUFFICIENTproperly. and E.
COOLING2. Low refrigerant charge-evident 2. Refer to B-1 and E.
by bubbles in sight glass.
3. Compressor not pumping. 3. Refer to B-2 and B-3
G.1. Belt tension. 1. Adjust belt tension.
COMPRESSOR2. Excessive head pressure. 2. Refer to A-1 through
BELTA-4 and C-6.
SLIPPING3. Incorrect alignment of pulleys 3. Repair as needed.
or worn belt not riding properly.
4. Nicked or broken pulley. 4. Replace as needed.
5. Seized compressor. 5. Replace compressor.
1. Loose or missing mounting bolts. 1. Repair as necessary.
2. Broken mounting bracket. 2. Replace bracket.
3. Loose flywheel or clutch 3. Repair as necessary.
retaining bolt.
H.4. Rough idler pulley bearing. 4. Replace bearing.
ENGINE5. Bent, loose, or improperly 5. Repair as necessary.
NOISEmounted engine drive pulley.
AND/OR6. Defective compressor bearing. 6. Replace bearing.
VIBRATION7. Insecure mountings of 7. Repair as necessary.
accessories; generator, power
steering, air filter, etc.
8. Excessive head pressure. 8. Refer to A-1, A-2, A-3
A-4 and C-6.
9. Incorrect compressor oil level. 9. Refer to compressor Oil
Level Check.
HEATER AND AIR CONDITIONING - CIRCUIT
DIAGRAMS
1.For details of heating and air conditioning
electrics
See Electrical Trouble Shooting
Manual.

AIR CONDITIONING
1
ADJUSTMENT GENERAL PRECAUTIONS
The refrigerant used in the air conditioning system is
HFC (Hydrofluorocarbon) R134a.
WARNING: R134a is a hazardous liquid
and when handled incorrectly can cause
serious injury. Suitable protective clothing
must be worn when carrying out servicing
operations on the air conditioning system.
WARNING: R134a is odourless and
colourless. Do not handle or discharge in
an enclosed area, or in any area where the
vapour or liquid can come in contact with naked
flame or hot metal. R134a is not flammable but
can form a highly toxic gas.
WARNING: Do not smoke or weld in areas
where R134a is in use. Inhalation of
concentrations of the vapour can cause
dizziness, disorientation. uncoordination,
narcosis, nausea or vomiting.
WARNING: Do not allow fluids other than
R134a or compressor lubricant to enter the
air conditioning system. Spontaneous
combustion may occur.
WARNING: R134a splashed on any part of
the body will cause immediate freezing of
that area. Also refrigerant cylinders and
replenishment trolleys when discharging will
freeze skin to them if contact is made.
WARNING: The refrigerant used in an air
conditioning system must be reclaimed in
accordance with the recommendations
given with a Refrigerant Recovery Recycling
Recharging Station.
NOTE: Suitable protective clothing
comprises: Wrap around safety glasses or
helmet, heatproof gloves, rubber apron or
waterproof overalls and rubber boots.REMEDIAL ACTIONS
1.If liquid R134a strikes the eye, do not rub it.
Gently run large quantities of eyewash over the
eye to raise the temperature. If eyewash is not
available cool, clean water may be used. Cover
eye with clean pad and seek immediate medical
attention.
2.If liquid R134a is splashed on the skin run large
quantities of water over the area as soon as
possible to raise the temperature. Carry out the
same actions if skin comes into contact with
discharging cylinders. Wrap affected parts in
blankets or similar material and seek immediate
medical attention.
3.If suspected of being overcome by inhalation of
R134a vapour seek fresh air. If unconscious
remove to fresh air. Apply artificial respiration
and/or oxygen and seek immediate medical
attention.
NOTE: Due to its low evaporating
temperature of -30°C, R134a should be
handled with care.
WARNING: Do not allow a refrigerant
container to be heated by a direct flame or
to be placed near any heating appliance. A
refrigerant container must not be heated above
50°C.
WARNING: Do not leave a container of
refrigerant without its cap fitted. Do not
transport a container of refrigerant that is
unrestrained, especially in the boot of a car.

82AIR CONDITIONING
2
ADJUSTMENT SERVICING PRECAUTIONS
Care must be taken when handling refrigeration
system components. Units must not be lifted by their
hoses, pipes or capillary lines. Hoses and lines must
not be subjected to any twist or stress. Ensure that
hoses are positioned in their correct run before fully
tightening the couplings, and ensure that all clips and
supports are used. Torque wrenches of the correct
type must be used when tightening refrigerant
connections to the stated value. An additional wrench
must be used to hold the union to prevent twisting of
the pipe.
Before connecting any hose or pipe ensure that
refrigerant oil is applied to the seat of the new '0' ring
but not to the threads.
Check the oil trap for the amount of oil lost.
All protective plugs on components must be left in
place until immediately prior to connection.
The receiver/drier contains desiccant which absorbs
moisture. It must be positively sealed at all times.
CAUTION: Whenever the refrigerant
system is opened, the receiver/drier must
be renewed immediately before evacuating
and recharging the system.
Use alcohol and a clean cloth to clean dirty
connections.
Ensure that all new parts fitted are marked for use
withR134a.
Refrigerant oil
Use the approved refrigerant lubricating oil:
Nippon Denso ND-OIL 8
Unipart R134a ND-OIL8
CAUTION: Do not use any other type of
refrigerant oil.
Refrigerant oil easily absorbs water and must not be
stored for long periods. Do not pour unused oil back
into the container.
When renewing system components, add the
following quantities of refrigerant oil:
Condenser 40ml..........................................................
Evaporator 80ml..........................................................
Pipe or hose 20ml........................................................
Receiver/drier 20ml......................................................
Total of refrigerant oil in system = 180ml = 6.3 Fl
ozA new compressor is sealed and pressurised with
Nitrogen gas, slowly release the sealing cap, gas
pressure should be heard to release as the seal is
broken.
NOTE: A new compressor should always
have its sealing caps in place and must
not be removed until immediately prior to
fitting
Fitting a new compressor
A new compressor is supplied with an oil fill (X) of:
180ml
A calculated quantity of oil must be drained from a
new compressor before fitting.
To calculate the quantity of oil to be drained:
1.Remove sealing plugs from the OLD compressor
2.Invert compressor and gravity drain oil into
measuring cylinder. Rotating the compressor
clutch plate will assist complete draining.
3.Note the quantity of oil drained (Y).
4.Calculate the quantity (Q) of oil to be drained
from the NEW compressor using the following
formula:
X - (Y + 20ml) = Q
Rapid refrigerant discharge
When the air conditioning system is involved in
accident damage and the circuit is punctured, the
refrigerant is discharged rapidly. The rapid discharged
of refrigerant will also result in the loss of most of the
oil from the system. The compressor must be
removed and all the remaining oil in the compressor
drained and refilled as follows:
1.Gravity drain all the oil, assist by rotating the
clutch plate (not the pulley).
2.Refill the compressor with the following amount
of new refrigerant oil:
130ml
3.Plug the inlet and outlet ports.

AIR CONDITIONING
3
ADJUSTMENT SERVICING EQUIPMENT
The following equipment is required for full servicing
of the air conditioning system.
Recovery, recycling and charging station
Leak detector
Thermometer +20°C to -60°C
Safety goggles and gloves
REFRIGERANT RECOVERY RECYCLING
RECHARGING
WARNING: The air conditioning system is
charged with a high pressure, potentially
toxic refrigerant. Repairs or servicing must
only be carried out by an operator familiar with
both the vehicle system and the charging and
testing equipment.
All operations must be carried out in a
well-ventilated area away from open flame and
heat sources.
Always wear safety goggles and gloves when
opening refrigerant connections.
WARNING: Wear eye and hand safety
protection. Open connections slowly in
case liquid or pressure is present. Allow to
bleed off slowly.
CAUTION: Overcharging air conditioning
system will cause excessive head
pressure.
An air conditioning portable Refrigerant Recovery
Recycling Recharging Station for use with R134a
refrigerant incorporates all the features necessary to
recover refrigerant R134a from the air conditioning
system, to filter and remove moisture, to evacuate and
recharge with the reclaimed refrigerant. The unit can
also be used for performance testing and air
conditioning system analysis.
The operator must adhere to the equipment
manufacturer's instructions.Recovery and recycling
1. High pressure servicing connection
2. Low pressure servicing connection
1.Connect a Refrigerant Station to the high and
low pressure servicing connections.
2.Operate the refrigerant recovery system
according to the manufacturer's instructions.
3.Measure the amount of oil discharged from the
system. Add an equal amount of new refrigerant
oil to compressor before evacuation sequence.
WARNING: Refrigerant must always be
recycled before reuse, to ensure that the
purity of the refrigerant is high enough for
safe use in the air conditioning system.
Recycling should always be carried out with
equipment which is design certified by
Underwriter Laboratory Inc. for compliance with
SAE-J1991. Other equipment may not recycle
refrigerant to the required level of purity.
A R134a Refrigerant Recovery Recycling
Recharging Station must not be used with any
other type of refrigerant.
Refrigerant R134a from domestic and commercial
sources must not be used in motor vehicle air
conditioning systems.

82AIR CONDITIONING
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ADJUSTMENT Evacuation and recharging
1.Add refrigerant oil to compressor if necessary.
2.Renew the receiver/drier.
CAUTION: When a major repair has been
carried out, a leak test should be carried
out using inert gas.
3.Connect a Refrigerant Station to the high and
low pressure servicing connections.
CAUTION: Whenever the refrigerant
system is opened, the receiver/drier must
be renewed immediately before evacuating
and recharging the system.
4.Operate the refrigerant evacuation system
according to the manufacturer's instructions.
NOTE: If the vacuum reading is below
700mmHg after 15 minutes, suspect a leak
in the system. Partially recharge the
system and check for leaks using an electronic
leak tester. Check suction lines first, then run the
compressor for 5 minutes and then check the high
pressure lines.
CAUTION: The system must be evacuated
immediately before recharging
commences. Delay between evacuation
and recharging is not permitted.
5.Operate the refrigerant recharging system
according to the manufacturer's instructions:-
Refrigerant required to charge system:
Without rear air conditioning = 0.90kg (32 fl/oz)
With rear air conditioning = 1.15kg (40 fl/oz)
6.If the full charge has not been accepted by the
system, start the engine and run it at 1500
rev/min for a minimum of 2 minutes.
Switch on the air conditioning system, open the
car windows, set the temperature control to cold
and switch the blower to maximum speed.
7.Consult Refrigerant Station Manual for correct
procedure to complete the charge.
8.Carry out the air conditioning system
performance test.LEAK TEST SYSTEM
The following instructions refer to an electronic type
Refrigerant Leak Detector for use with R134a, which
are the safest and most sensitive.
CAUTION: When a major repair has been
carried out, a leak test should be carried
out using an inert gas (see below).
1.Place the vehicle in a well ventilated area but
free from draughts, as leakage from the system
could be dissipated without detection.
2.Follow the instructions issued by the
manufacturer of the particular leak detector
being used.
3.Commence searching for leaks by passing the
detector probe around all joints and components,
refrigerant gas is heavier than air.
4.Insert the probe into an air outlet of the
evaporator or into the evaporator drain tube.
Switch the air conditioning blower on and off at
intervals of ten seconds. Any leaking refrigerant
will be gathered in by the blower and detected.
5.Insert the probe between the magnetic clutch
and compressor to check the shaft seal for
leaks.
6.Check all service valve connections, valve plate,
head and base plate joints and back seal plate.
7.Check the condenser for leaks at the pipe
unions.
8.If any leaks are found, the system must be
discharged before rectification.
9.Rectify any leaks and recheck for leaks during
evacuation prior to charging.
Leak test using inert gas
Use Nitrogen or Helium gas.
1.Connect gas line to recharging station.
2.Pressurise system to 3 bar.
3.Carry out leak test as above.

AIR CONDITIONING
5
ADJUSTMENT AIR CONDITIONING SYSTEM - PERFORMANCE
TEST
WARNING: R134a is hazardous, refer to
the GENERAL PRECAUTIONS given at the
beginning of this section.
Carry out this test with bonnet and doors or windows
open, air conditioning switched on, temperature
control set to cold and blower at maximum speed. Set
the air supply control to supply fresh air.
1.Close low pressure valve on refrigerant station.
2.Close high pressure valve on refrigerant station.
3.Connect a Refrigerant Station to the high and
low pressure servicing connections.4.Insert dry bulb thermometer into cold air outlet
and position dry and wet bulb thermometer close
to outside air inlet.
Do not spill water from the wet thermometer
(psychrometer).
5.Start engine and run it at 1500 rev/min for 10
minutes with air conditioning switched on.
6.Check that sight glass is free of bubbles.
7.Read both pressure gauges and thermometers.
Check readings against table below with
humidity between 60% and 80%. If readings are
incorrect.
See Fault diagnosis, Refrigeration
System Faults.
8.Switch off air conditioning, stop engine,
disconnect test equipment.
Performance range
Intake temperature Outlet temperature Low pressure High pressure
20 - 24°C4-10°C 18 - 28 lbf/in
2213 - 299 lbf/in2
1.2 - 1.9 bar 14.7 - 20.6 bar
25 - 29°C9-19°C 27 - 37 lbf/in2256 - 341 lbf/in2
1.9 - 2.6 bar 17.6 - 23.5 bar
30 - 35°C20-27°C 33 - 47 lbf/in2299 - 384 lbf/in2
2.3 - 3.2 bar 20.6 - 26.5 bar
Table 1
Ambient Compound Gauge High Pressure
Temperature Readings Gauge Readings
ÊC°F bar lbf/in
2bar lbf/in2
16 60 1,03-1,4 15-20 6,9-10,3 100-150
26,7 80 1,4-1,72 20-25 9,6-13,1 140-190
38 100 1,72-2,1 25-30 12,4-15,5 180-225
43,5 110 2,1-2,4 30-35 14,8-17,2 215-250