heating LAND ROVER DISCOVERY 1995 Owner's Guide

HEATING AND VENTILATION
1
SPECIFICATIONS, TORQUE TORQUE VALUES
NOTE: Torque wrenches should be regularly checked for accuracy to ensure that all fixings are
tightened to the correct torque.
Nm
METRIC
M5 6......................................................................................................
M6 9......................................................................................................
M8 25.....................................................................................................
M10 45...................................................................................................
M12 90...................................................................................................
M14 105..................................................................................................
M16 180..................................................................................................
UNC / UNF
1/4 9......................................................................................................
5/16 24...................................................................................................
3/8 39.....................................................................................................
7/16 78...................................................................................................
1/2 90.....................................................................................................
5/8 136....................................................................................................
Torque values above apply to all screws and bolts used unless otherwise specified.

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
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.