coolant LAND ROVER DISCOVERY 1999 Owners Manual

HEATING AND VENTILATION
80-22REPAIRS
Heater assembly - models without air
conditioning
$% 80.20.01.99
Remove
1.Drain cooling system.
l

+ COOLING SYSTEM - Td5,
ADJUSTMENTS, Drain and refill.
l

+ COOLING SYSTEM - V8,
ADJUSTMENTS, Drain and refill.
2. Diesel models: Remove 3 bolts and remove
engine cover.
3.Release clips and disconnect coolant hoses
from heater pipes.
CAUTION: Always fit plugs to open
connections to prevent contamination.
4.Remove facia assembly.

+ INTERIOR TRIM COMPONENTS,
REPAIRS, Fascia.5.Disconnect harness multiplug from heater
blower motor.
6.Remove bolt and 2 nuts securing heater
blower housing assembly to body and remove
blower.
7.Disconnect 2 drain tubes from base of heater.

HEATING AND VENTILATION
REPAIRS 80-23
8.Remove 2 screws securing console bracket to
tunnel and remove bracket.
9.Release radio coaxial cable from behind heater
pipes.
10.Protect the carpet from coolant spillage.
11.Remove 4 nuts and 1 bolt securing heater to
body.
12.Remove heater from vehicle.
13.Remove 2 screws securing heater RH and LH
footwell outlet duct to heater casing and
remove ducts. 14.Remove 2 screws securing matrix pipe bracket
to heater casing.
15.Remove screw securing pipe clamp to heater
casing and remove clamp.
16.Carefully remove matrix from heater.
Refit
1.Fit matrix into heater casing.
2.Fit screws securing pipe bracket to heater
casing.
3.Fit pipe clamp and secure with screw.
4.Fit heater ducts and secure with screws.
5.Position heater assembly to vehicle, ensure
heater coolant pipe grommet is correctly
located in bulkhead and secure with nuts and
bolt.
6.Fit radio coaxial cable behind heater pipes.
7.Fit console bracket and secure with screws.
8.Connect drain tubes to base of heater.
9.Fit blower unit to heater and secure to body
with nuts and bolt.
10.Connect harness multiplug to blower motor.
11.Fit facia assembly

+ INTERIOR TRIM COMPONENTS,
REPAIRS, Fascia.
12.Connect heater hoses and secure with clips.
13. Diesel models: Fit engine cover and secure
with bolts.
14.Refill cooling system
l

+ COOLING SYSTEM - Td5,
ADJUSTMENTS, Drain and refill.
l

+ COOLING SYSTEM - V8,
ADJUSTMENTS, Drain and refill.

HEATING AND VENTILATION
REPAIRS 80-29
Heater matrix
$% 80.20.29
Remove
1.Remove heater assembly.

+ HEATING AND VENTILATION,
REPAIRS, Heater assembly - models with
air conditioning.
2.Remove 2 screws securing coolant pipe
saddles and remove saddles.
3.Loosen screws securing coolant pipes to
matrix, release clamps and remove coolant
pipes.
4.Remove and discard 'O' rings.
5.Remove heater matrix.
Refit
1.Position heater matrix, using new 'O' rings fit
coolant pipes and align clamps.
2.Fit saddle clamps and secure with screws
3.Tighten coolant pipe clamp screws.
4.Fit heater assembly.

+ HEATING AND VENTILATION,
REPAIRS, Heater assembly - models with
air conditioning.
Pipe - Heater - Feed
$% 80.25.07
Remove
1.Remove heater return pipe.

+ HEATING AND VENTILATION,
REPAIRS, Pipe - Heater - Return.
2.Release clip securing heater feed hose to
heater feed pipe and disconnect hose from
pipe.
3.Remove nut securing heater feed pipe to
plenum chamber.
4.Press quick release connector and release
heater feed pipe from plenum chamber.
5.Remove and discard 'O' ring from pipe.
Refit
1.Fit new 'O' ring to heater feed pipe and lubricate
with castor oil.
2.Secure heater feed pipe to plenum chamber.
3.Fit and tighten nut securing heater feed pipe to
plenum chamber.
4.Connect heater feed hose to heater feed pipe
and secure with clip.
5.Fit heater return pipe.

+ HEATING AND VENTILATION,
REPAIRS, Pipe - Heater - Return.
M80 0435
23
4

HEATING AND VENTILATION
80-30REPAIRS
Pipe - Heater - Return
$% 80.25.12
Remove
1.Drain engine coolant.

+ COOLING SYSTEM - V8,
ADJUSTMENTS, Drain and refill.
2.Release clip securing heater return hose to
heater return pipe and disconnect hose from
pipe.
3.Remove bolt securing heater return pipe to
heater feed pipe.
4.Release clips securing engine harness and
vacuum pipe to heater return pipe.
5.Remove bolt securing heater return pipe to
cylinder head.
6.Release clip securing engine coolant hose to
heater return pipe.
7.Release engine coolant hose from heater
return pipe and collect pipe.Refit
1.Connect engine coolant hose to heater return
pipe and secure with clip.
2.Position heater return pipe to cylinder block and
secure with bolt.
3.Secure engine harness and vacuum pipe to
heater return pipe and secure with clips.
4.Fit and tighten bolt securing heater return pipe
to heater feed pipe.
5.Connect heater return hose to heater return
pipe and secure with clip.
6.Refill engine coolant.

+ COOLING SYSTEM - V8,
ADJUSTMENTS, Drain and refill.
M80 0437
M80 0438
4
46
7
5

HEATING AND VENTILATION
REPAIRS 80-31
Fuel burning heater - (FBH) - Td5
$% 80.40.01.99
Remove
1.Release fixings and remove battery cover.
2.Disconnect battery earth lead.
3.Clamp feed and return coolant hoses at FBH.
4.Position container to collect spillage.
5.Release clips, disconnect coolant feed and
return hoses from FBH.
CAUTION: Before disconnecting or
removing components, ensure the
immediate area around joint faces and
connections are clean. Plug open
connections to prevent contamination.
6.Disconnect 2 multiplugs from FBH.7.Position container to collect spillage and
disconnect quick release fuel pipe from FBH.
CAUTION: Before disconnecting any part of
the fuel system, it is imperative that all dust,
dirt and debris is removed from around
components to prevent ingress of foreign
matter into fuel system.
8.Remove Torx bolt securing FBH to bulkhead
mounting bracket.
9.Release and remove FBH.
10.Collect locating bushes from pegs.
Refit
1.Fit bushes to pegs.
2.Align FBH to pegs, fit Torx bolt and tighten to 25
Nm (18 lbf.ft).
3.Clean quick release connection and fit fuel pipe
to FBH.
4.Connect multiplugs to FBH.
5.Connect coolant hoses to FBH and secure with
clips.
6.Release clamps from hoses.
7.Connect battery earth lead.
8.Fit and secure battery cover.
9.Top-up cooling system.

+ MAINTENANCE, PROCEDURES,
Cooling system.

AIR CONDITIONING
82-2DESCRIPTION AND OPERATION
A/C control system component layout
RH drive shown, LH drive similar
1Air temperature control ECU
2Heater coolant temperature sensor
3Evaporator temperature sensor
4Dual pressure switch5Ambient temperature sensor
6Sunlight sensor
7In-car temperature sensor

AIR CONDITIONING
DESCRIPTION AND OPERATION 82-9
Heater assembly
1Distribution servo motor
2Refrigerant inlet and outlet connector block
3RH blend flap servo motor4Thermostatic expansion valve
5LH blend flap servo motor
The heater assembly controls the temperature and distribution of air supplied to the distribution ducts, and is similar
to the heater assembly installed in non A/C vehicles.

+ HEATING AND VENTILATION, DESCRIPTION AND OPERATION, Description. The only differences from
the heater assembly in non A/C vehicles are as follows:
lThe thermostatic expansion valve, evaporator and evaporator temperature sensor are installed at the air inlet
side of the casing.
lThree servo motors operate the control flaps instead of control cables.
lA coolant temperature sensor is installed against the heater matrix.
The servo motors are controlled by the ATC ECU. Feedback potentiometers in the servo motors provide the ATC ECU
with flap position signals.

AIR CONDITIONING
82-10DESCRIPTION AND OPERATION
Temperature and distribution control
Figure shows flaps set for medium heat to face level and footwell outlets
1Windscreen/Side windows outlet
2Heater assembly casing
3Air inlet
4Evaporator5Heater matrix
6Front footwells outlet
7Rear footwells outlet
8Face level outlet
Control system
The control system operates the refrigerant system and the control flaps in the heater assembly to control the
temperature and distribution of air in the vehicle interior. It also outputs signals to the fresh/recirculated air servo motor
and the blower to control the volume and source of inlet air. The control system consists of:
lAn Air Temperature Control (ATC) ECU.
lA dual pressure switch.
lAn evaporator temperature sensor.
lAn in-car temperature sensor.
lA sunlight sensor.
lA heater coolant temperature sensor.
lAn ambient temperature sensor.

AIR CONDITIONING
DESCRIPTION AND OPERATION 82-11
ATC ECU
The ATC ECU is installed in the centre of the fascia, below the radio. An integral control panel on the ATC ECU
contains switches for system control inputs and a LCD to provide system status information.
Inputs from sensors and the control panel switches are processed by the ATC ECU, which then outputs the
appropriate control signals.
ATC ECU connectors
ATC ECU connector pin details
Connector/Pin
No.Description Input/Output
C0791
1 Battery power supply Input
2 Ignition power supply Input
3 Sensor power supply Output
4Earth -
5 Display illumination Input
6 Not used -
7 Not used -
8 Sensor earth -
C0792
1 Night lighting/dimming Input
2 Vehicle speed Input
3 Hand of drive Input
4 Distribution flaps position Input
5 Heater coolant temperature Input
6 External air temperature Input
7 In-car air temperature Input
8 Blower power transistor collector voltage Input
9 Not used -
10 Not used -
11 Windscreen heater status Input
12 Rear screen heater status Input
13 Rear air conditioning ON Input

AIR CONDITIONING
DESCRIPTION AND OPERATION 82-15
Dual pressure switch
The dual pressure switch protects the refrigerant system from extremes of pressure. The normally closed switch is
installed in the top of the receiver drier. If minimum or maximum pressure limits are exceeded the switch contacts
open, causing the compressor clutch to be disengaged. The minimum pressure limit protects the compressor, by
preventing operation of the system unless there is a minimum refrigerant pressure (and thus refrigerant and
lubricating oil) in the system. The maximum pressure limit keeps the refrigerant system within a safe operating
pressure.
Dual pressure switch nominal operating pressures
Evaporator temperature sensor
The evaporator temperature sensor is an encapsulated thermistor that provides the ATC ECU with an input of the
evaporator air outlet temperature. The evaporator temperature sensor is installed in a clip which locates in the
evaporator matrix in the heater assembly. The ATC ECU uses the input to prevent the formation of ice on the
evaporator.
In-car temperature sensor
The in-car temperature sensor is an encapsulated thermistor that provides the ATC ECU with an input of cabin air
temperature. The sensor is integrated into the inlet of an electric fan, which is installed behind a grille in the fascia
outboard of the steering column. The fan runs continuously, while the ignition is on, to draw air through the grille and
across the sensor.
Sunlight sensor
The sunlight sensor consists of two diodes that provide the ATC ECU with inputs of light intensity, one as sensed
coming from the left of the vehicle and one as sensed coming from the right. The inputs are used as a measure of the
solar heating effect on vehicle occupants. The sensor is installed in the centre of the fascia upper surface.
Heater coolant temperature sensor
The heater coolant temperature sensor is an encapsulated thermistor that provides the ATC ECU with an input related
to heater matrix coolant temperature. The sensor is installed in the casing of the heater assembly and presses against
the end tank of the heater matrix.
Ambient temperature sensor
The ambient temperature sensor is an encapsulated thermistor that provides the ATC ECU with an input of external
air temperature. The sensor is attached to the cooling fan mounting bracket in front of the condenser.
Limit Opening pressure, bar (lbf.in2) Closing pressure, bar (lbf.in2)
Minimum 2.0 (29.0), pressure decreasing 2.3 (33.4), pressure increasing
Maximum 32 (464), pressure increasing 26 (377), pressure decreasing