1995 LAND ROVER DISCOVERY lock

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.

HEATING AND VENTILATION
3
REPAIR Air direction
3.Set control fully clockwise
4.Release outer cable from 2 clips on unit.
5.Release cable from stud on flap lever.
6.Remove control cable from control lever.
Temperature
7.Set RH control fully clockwise, LH control fully
anti-clockwise
8.Release outer cable from 2 clips on unit.
9.Release cable from stud on flap lever.
10.Remove control cable from control lever.
Refit
11.Reverse removal procedure. Check the
satisfactory function of the controls before fitting
louvre vent panel.RESISTOR UNIT
Service repair no - 80.20.17
Remove
1.Open glove box, manoeuvre side springs
through cut-outs and lower lid.
2.Remove 2 screws securing resistor unit to
trunking.
3.Disconnect multiplug and remove resistor unit.
Refit
4.Reverse removal procedure.

HEATING AND VENTILATION
5
REPAIR RECIRCULATION SWITCH
Service repair no - 80.10.27
Remove
1.Release fascia centre louvre vent panel from its
fitted position to gain access to rear of panel.
See CHASSIS AND BODY, Repair, Dash
Panel Central Louvre Panel
2.Disconnect multiplug from switch
3.From the rear, push switch out of panel.
Refit
4.Reverse removal procedure.RECIRCULATION FLAP SOLENOID
Service repair no - 80.10.43
Remove
1.Open glove box, manoeuvre side springs
through cut-outs and lower lid.
2.Remove 2 locknuts securing cruise control ECU
to bracket.
3.Position cruise control ECU aside.
4.Remove 2 screws securing recirculation
solenoid to casing.
5.Release solenoid from lever.
6.Disconnect multiplug and remove solenoid.
Refit
7.Reverse removal procedure.

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.

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
6
ADJUSTMENT SYSTEM TEST
1.Place the vehicle in a ventilated, shaded area
free from excessive draught, with the doors and
windows open.
2.Check that the surface of the condenser is not
restricted with dirt, leaves, flies, etc. Do not
neglect to check the surface between the
condenser and the radiator. Clean as necessary.
3.Switch on the ignition and the air conditioner air
flow control. Check that the blower is operating
efficiently at low, medium and high speeds.
Switch off the blower and the ignition.
4.Check that the evaporator condensate drain
tubes are open and clear.
5.Check the tension of the compressor driving belt,
and adjust if necessary.
6.Inspect all connections for the presence of
refrigerant oil. If oil is evident, check for leaks,
and repair as necessary.
NOTE: The compressor oil is soluble in
Refrigerant R134a and is deposited when
the refrigerant evaporates from a leak.
7.Start the engine.
8.Set the temperature controls to cold and switch
the air conditioner blower control on and off
several times, checking that the magnetic clutch
on the compressor engages and releases each
time.9.With the temperature control at maximum
cooling and the blower control at high speed,
warm up the engine and fast idle at 1000
rev/min. Check the sight glass for bubbles or
foam. The sight glass should be generally clear
after five minutes running, occasional bubbles
being acceptable. Continuous bubbles may
appear in a serviceable system on a cool day, or
if there is insufficient air flow over the condenser
at a high ambient temperature.
10.Repeat at 1800 rev/min.
11.Gradually increase the engine speed to the high
range, and check the sight glass at intervals.
12.Check for frosting on the service valves.
13.Check the high pressure hoses and connections
by hand for varying temperature. Low
temperature indicates a restriction or blockage at
that point.
14.Switch off the air conditioning blower and stop
the engine.
15.If the air conditioning equipment is still not
satisfactory, carry out a pressure test as
previously described in this section.
COMPRESSOR DRIVE BELT
Service repair no - 82.10.01.
Tdi -
See ENGINE, Repair, Compressor drive belt
V8i and MpiSee ENGINE, Repair, Drive belt