1995 LAND ROVER DISCOVERY cooling

57STEERING
6
REPAIR Refit
6.Position reservoir, connect feed and return
hoses and tighten clamps to
3 Nm.
7.Fit reservoir in clamp, tighten clamp bolt.
8.Fill reservoir to 'MAX' mark on dipstick with
power steering fluid.
See LUBRICANTS,
FLUIDS AND CAPACITIES, Information,
Recommended Lubricants and Fluids
9.Fit undertray.
10.Bleed power steering system.
See Power
Steering System - Bleed
POWER STEERING PUMP DRIVE BELT
Service repair no - 57.20.02
NOTE: For details of drive belt remove and
refit.
See ENGINE, Repair, Drive Belt
POWER STEERING PUMP - V8i
Service repair no - 57.20.14
NOTE: The power steering pump is not
serviceable. Fit new pump if worn or
damaged.
Remove
1.Disconnect battery negative lead.
2.Remove drive belt from steering pump.
See
ENGINE, Repair, Drive Belt
3.Remove undertray.
4.Remove fan blades and viscous coupling.
See
COOLING SYSTEM, Repair, Viscous
Coupling, Fan Blades, Pulley and Fan Cowl
5.Position drain tin beneath steering pump.
6.Using a 9 mm Allen key to restrain steering
pump pulley, remove 3 bolts securing pulley to
pump; remove pulley.

STEERING
7
REPAIR 7.Loosen clamp securing reservoir hose to
steering pump; disconnect hose.
8.Disconnect high pressure pipe from steering
pump.
CAUTION: Plug the connections.
9.Release ht lead from clip
10.Remove 3 bolts securing steering pump.
Remove pump and recover engine lifting
bracket.
NOTE:Do not carry out further
dismantling if component is removed for
access only.
11.Remove 5 bolts securing front mounting plate.
12.Fit front mounting plate to replacement steering
pump. Tighten bolts to
9 Nm.
Refit
13.Position steering pump and engine lifting plate,
fit bolts. Tighten to
35 Nm.Secure ht lead in
clip.
14.Connect high pressure pipe to steering pump,
tighten union to
20 Nm.
15.Connect reservoir hose to steering pump.
Tighten clamp to
3 Nm.
16.Position pulley to pump, coat threads of bolts
with Loctite 242.
17.Restrain pulley using a 9 mm Allen key, fit bolts.
Tighten to
10 Nm.
18.Fit drive belt.See ENGINE, Repair, Drive Belt
19.Fit fan blades and viscous coupling.See
COOLING SYSTEM, Repair, Viscous
Coupling, Fan Blades, Pulley and Fan Cowl
20.Fit undertray.
21.Reconnect battery negative lead.
22.Bleed power steering system.
See Power
Steering System - Bleed
POWER STEERING PUMP - Tdi
Service repair no - 57.20.14
Remove
1.Remove fan blades and viscous coupling.
See
COOLING SYSTEM, Repair, Viscous
Coupling, Fan Blades, Pulley and Fan Cowl
2.Restrain steering pump pulley, loosen but do not
remove 3 bolts securing pulley.
3.Remove drive belt.
See ENGINE, Repair,
Drive Belt
4.Remove 3 bolts securing steering pump pulley,
remove pulley.
5.Remove undertray.
6.Position drain tin beneath steering pump.

57STEERING
8
REPAIR 7.Loosen clamp securing reservoir hose to
steering pump, disconnect hose.
8.Disconnect high pressure pipe from steering
pump.
CAUTION: Plug the connections.
9.Remove 4 bolts securing steering pump to
mounting bracket, remove pump.
NOTE:Do not carry out further
dismantling if component is removed for
access only.
10.Remove 3 bolts securing mounting plate to
pump, remove plate.
11.Fit mounting plate to replacement steering
pump. Tighten bolts to
9 Nm.
Refit
12.Position steering pump, fit 3 bolts. Tighten to
35
Nm.
13.Connect high pressure pipe to steering pump.
Tighten to
20 Nm.
14.Connect reservoir hose to steering pump.
Tighten clamp to
3 Nm.
15.Position pulley to steering pump, coat threads of
bolts with Loctite 242; fit but do not fully tighten 3
bolts.
16.Fit drive belt.
See ENGINE, Repair, Drive Belt
17.Restrain steering pump pulley, tighten bolts to10
Nm.
18.Fit fan blades and viscous coupling.See
COOLING SYSTEM, Repair, Viscous
Coupling, Fan Blades, Pulley and Fan Cowl
19.Fit undertray.
20.Bleed power steering system.
See Power
Steering System - Bleed

HEATING AND VENTILATION
3
DESCRIPTION AND OPERATION
Controls set for unheated air to footwells and face level vents
Heater and ventilation operation
The heating and ventilation system contains a heater
matrix, which is connected to the engine cooling
system, and a 4 speed fan for air distribution. Engine
coolant is circulated through the heater matrix
continuously, except when the temperature controls
are set to COLD.
Recirculated air
When the recirculation switch is pressed, an electrical
servo operates and fully closes the fresh air intake
flap.
Fresh air
When the recirculation switch is returned to the OFF
position, the electrical servo returns and fully opens
the fresh air intake flap.Heated air
Temperature output is controlled by the temperature
controls which move the air direction and temperature
flaps independently to increase or decrease the
volume of air flow through the heater matrix.
V8 Engine:When both controls are in the cold
position, the coolant valve is turned off.
Face level vent flap
Control at face level, flap fully open. All other vents
closed.
Control at face and foot level, flaps half open.
Unless an air conditioning unit is fitted, only fresh or
re-circulated air is available from the face level vents.
Demist vent flap
Control at demist, flap fully open. All other vents
closed.
Control at demist and foot level, flaps half open.

HEATING AND VENTILATION
1
FAULT DIAGNOSIS HEATER OUTPUT
Symptom:-
Heater emits cold air.
1.Engine running: Check coolant valve opens as a
temperature control is moved from COLD.
2.Check for engine running cold.
See COOLING
SYSTEM, Fault diagnosis, Engine Runs Cold
3.Check heater pipes and hoses for blockage or
restriction.
4.Check heater matrix for blockage or restriction,
flush system.
Heater emits warm air.
5. Engine running:Check coolant valve closes
when both temperature controls are moved to
COLD.

82AIR CONDITIONING
2
DESCRIPTION AND OPERATION SCHEMATIC LAYOUT OF THE AIR CONDITIONING
SYSTEM
1. Compressor
2. Condenser
3. Receiver/drier
4. Thermostatic expansion valve
5. Evaporator
6. Capillary tube
7. Dual pressure switch
8. Cooling fans to maintain air flow
9. Compressor high pressure relief valve
10. Sight glass - refrigerant
11. Drying agent - receiver/drier
12. Blower motorA1 Ambient air flow through condenser
A2 Ambient air flow through fan and evaporator
A3 Cooled air flow to vehicle interior
F1 High pressure high temperature refrigerant
vapour
F2 High pressure slightly subcooled refrigerant
liquid
F3 High pressure slightly subcooled refrigerant
liquid with moisture, vapour bubbles and foreign
matter removed
F4 Low pressure low temperature mixed liquid and
vapour
F5 Low pressure slightly super heated refrigerant
vapour

AIR CONDITIONING
3
DESCRIPTION AND OPERATION AIR CONDITIONING SYSTEM OPERATION
The air conditioning system provides the means of
supplying cooled and dehumidified, fresh or
recirculated air to the interior of the vehicle. The
cooling effect is obtained by blowing air through the
matrix of an evaporator unit and when required,
mixing that air with heated air by means of the heater
distribution and blend unit, to provide the conditions
required inside the vehicle. The volume of conditioned
air being supplied is controlled by a variable speed
blower.
A sealed system, charged with Refrigerant R134a,
together with a blower unit, blend unit and control
system combine to achieve the cooled air condition.
For air conditioning air distribution system.
See
HEATING AND VENTILATION, Description and
operation, Heating and ventilation unit
The air conditioning system comprises five major
units:
1.An engine-mounted compressor.
2.A condenser mounted in front of the radiator.
3.A receiver/drier unit located in front of the
condenser.
4.Thermostatic expansion valve mounted above
the evaporator.
5.An evaporator unit mounted in front of the heater
matrix.
NOTE: Vehicles fitted with rear air
conditioning have an additional
evaporator/blower motor assembly located
behind the LH rear compartment lower trim panel.
These units are interconnected by hoses and pipes
carrying Refrigerant R134a, the evaporator is linked
into the vehicle ventilation system.
Refrigeration cycle
1. Compressor
The compressor (1), belt driven from the crankshaft
pulley, pressurises and circulates the refrigerant
through the system. Mounted on the compressor, an
electro-mechanical clutch maintains the correct
temperature and pressure by engaging or disengaging
to support the system's requirements. The clutch
action is normally controlled by a thermostat located
at the evaporator (5). The compressor is of the
swashplate type having fixed displacement.Should the temperature at the evaporator (5) fall low
enough for ice to begin to form on the fins, the
thermostat disengages the clutch and also isolates the
cooling fans relays. When the temperature at the
evaporator (5) rises to the control temperature, the
clutch is re-engaged.
Should the system pressure become excessive or
drop sufficiently to cause damage to the compressor
(1) a dual pressure switch (7), located in the high
pressure line, signals the relay unit to disengage the
clutch. The compressor also has an emergency high
pressure relief valve (9) fitted.
The cooling fans are controlled by engine temperature
when the air conditioning is not switched on.
2. Condenser
From the compressor, hot high pressure vaporised
refrigerant (F1) passes to the condenser (2), which is
mounted in front of the engine coolant radiator. Ram
air(A1) passing through the condenser (2),
supplemented by 2 cooling fans (8) mounted in front
of the condenser, cools the refrigerant vapour
sufficiently to form a high pressure slightly subcooled
liquid (F2).
3. Receiver/drier
This liquid then passes to a receiver/drier (3) which
fulfils two functions. It acts as a reservoir and moisture
extractor (11).
A sight glass (10), in the high pressure line, provides a
method of determining the state of the refrigerant
without breaking into the system.
4. Expansion valve
From the receiver/drier (3) the moisture free high
pressure liquid refrigerant (F3) passes through a
thermostatic expansion valve (4). A severe pressure
drop occurs across the valve and as the refrigerant
enters the evaporator space at a temperature of
approximately -5°C it boils and vaporises.

82AIR CONDITIONING
4
DESCRIPTION AND OPERATION 5. Evaporator
As this change of state occurs, a large amount of
latent heat is absorbed. The evaporator is therefore
cooled and as a result heat is extracted from the air
flowing across the evaporator. The air flow is
controlled by the ventilation fan which can be
operated at anyone of four speeds.
To prevent liquid passing through to the compressor,
a capillary tube (6), attached to the outlet pipe of the
evaporator (5) and connected to the thermostatic
expansion valve (4), controls the amount that the
valve opens and closes in relation to the temperature
of the low pressure high temperature refrigerant
vapour (F4) at the outlet. The atomised refrigerant
then passes through the evaporator (5). Fan blown air
(A2) passes through the matrix (A3) of the evaporator
and is cooled by absorption due to the low
temperature refrigerant passing through the
evaporator.
A thermostat is fitted in the airflow out of the
evaporator to sense the temperature of the exterior
fins. Should ice begin to form, due to a too cold
condition, it will signal to disengage the
electro-mechanical clutch on the compressor (1).
From the evaporator, low pressure slightly
superheated refrigerant (F5) passes to the
compressor to complete the cycle.AIR CONDITIONING CONTROL SYSTEM
The air conditioning control system comprises relays,
thermostat, pressure switches, and a control panel.
Inputs from outside the air conditioning system
comprise temperature information from the engine
cooling system. Together these controls, in
conjunction with the cooling fans, compressor clutch,
blower and heater distribution and blend unit enable
minimal input to maintain the required environment
inside the vehicle.
When air conditioning is not selected, air is supplied
by ram effect or blower to the areas selected by the
controls. The air mix flap on the blend unit controls the
temperature of the air being supplied. No cooled air is
available.
Selecting air conditioning provides the added facility of
cooled air available to be mixed as before. When
required a fully cold condition can be selected by
turning the temperature controls to cold, which
automatically closes the heated coolant access to the
heater matrix. Mixtures of cooled, fresh, and hot air
can be selected to give required interior environmental
conditions by selection at the control panel.
Dual pressure switch
This switch, located in the high pressure line between
the receiver drier and the expansion valve, monitors
refrigerant pressure and by means of the relay module
controls the following system functions:
1.Refrigerant pressure drops below 2.0 bar, 29
lbf/in
2(due to possible leakage), the
compressor's electro-mechanical clutch is
dis-engaged.
When pressure rises above 2.0 bar, 29 lbf/in
2the
compressor's clutch is re-engaged.
2.Refrigerant pressure rises above 32 bar, 455
lbf/in
2(due to possible blockage), even with
cooling fan operation, the compressor's
electro-mechanical clutch is dis-engaged.
When the pressure drops below 26 bar, 375
lbf/in
2the compressor clutch is re-engaged.