1996 LAND ROVER DEFENDER Workshop Manual

HEATING AND VENTILATION
1
DESCRIPTION AND OPERATION HEATING AND VENTILATION SYSTEM
Description
The heating and ventilation system is standard on all
models. Air conditioning is an optional system which
provides fully integrated climate control for the vehicle
interior.The heater assembly, comprising a matrix housed in a
distribution unit and a variable speed blower motor, is
located on one side of the engine compartment and
attached directly to the fascia bulkhead.
The heating controls are positioned on the outside of
the instrument binnacle and cable linked to
mechanical flaps in the distribution unit.
Heater assembly
1.Heater distribution unit
2.Fixings, heater to fascia bulkhead
3.Heater matrix
4.Blower motor housing
5.Circlip, impeller to blower motor
6.Impeller
7.Resistor unit and harness connector8.Fixings, blower motor mounting plate
9.Mounting plate, blower motor
10.Blower motor
11.Fixings, blower motor to mounting bracket
12.Temperature flap, air flow to heater matrix
13.Air flap, air supply to plenum chamber (heater
duct)

80HEATING AND VENTILATION
2
DESCRIPTION AND OPERATION HEATER OPERATION
The heater matrix (3), located in the distribution unit
(1), see J6341, is connected to the engine cooling
system. As water is circulated continuously through
the matrix, a selection of heated or ambient air is
controlled by two flaps within the distribution unit. The
temperature flap (12) controls the amount of ambient
air to the heater matrix, air being suppliedthrough a ducted vent on top of the vehicle front wing
to the blower motor (volute) housing (4). The blower
motor (10) can be used to boost the air flow into the
distribution unit. The air flap (13) controls the supply of
heated or ambient air from the heater unit into a
plenum chamber integeral with the vehicle fascia. Two
flaps in the plenum chamber (heater duct) distribute
the air flow to either the footwell vents or windscreen
demister vents as shown.
HEATER CONTROLS
1. Temperature control
Move the lever downwards to increase air
temperature or up to decrease air temperature.
2. Air distribution control
Lever fully up - windscreen vents only.
Lever midway - footwell and windscreen vents.
Lever fully down - footwell vents.3. Blower motor fan speed control
Move the lever progressively downwards to increase
fan speed. With the control at '0' the fan is switched
off and the volume of air entering the passenger
compartment is solely dependent on ram air when the
vehicle is moving.

HEATING AND VENTILATION
3
DESCRIPTION AND OPERATION Fresh air vents
Two fresh air vents are fitted in the windscreen frame
and are controlled independently of the vehicle
heating system. Each vent is operated separately.
To open the vents, push the lever to the right and then
down to the required position.

HEATING AND VENTILATION
1
REPAIR HEATER UNIT
Service repair no - 80.20.01
Remove
1.Remove bonnet and disconnect battery.
2.Remove radiator bottom hose at radiator union
and drain cooling system
See COOLING
SYSTEM, Repair, Drain and refill cooling
system
.
3.Slacken clips and remove heater hoses at
heater box unions.
4.Remove outer cable securing clips.
5.Slacken trunnions and remove control cables
from heater vent flap levers.
6.Remove heater wiring harness securing loop.
7.Disconnect harness multi-plug.
8.Remove interior bulkhead trim.
9.Remove lower nuts and bolts securing the
heater unit to the bulkhead.
10.Slacken heater unit upper retaining bolts.
11.Manoeuvre heater unit, complete with blower
motor, clear of air inlet duct and remove from
engine compartment.
12.If existing heater unit is to be refitted, remove
sealing rubber.
For heater matrix removal
See Heater matrix.
For blower motor removal
See Blower motor.
Refit
13.Smear a new heater unit sealing rubber with a
suitable impact adhesive and fit to heater.
14.Manoevre heater unit into position in engine
compartment, fit blower motor to air inlet duct
and locate upper fixing bolts.
15.Loosely fit heater unit lower fixing bolts.
16.Fully tighten upper fixing bolts.
17.Fully tighten lower fixings and refit interior
bulkhead trim.
18.Secure wiring harness and reconnect multi-plug.
19.Fit control cables to vent flap trunnions and
secure with outer cable clips.
20.Connect heater hoses.
21.Fit radiator bottom hose and refill cooling system
See COOLING SYSTEM, Repair, Drain and
refill cooling system
.
22.Fit bonnet and reconnect battery.

80HEATING AND VENTILATION
2
REPAIR BLOWER MOTOR
Service repair no - 80.20.15
Remove
1.Remove heater unit
See Heater unit.
2.Remove 3 nuts securing angled bracket to
heater unit. Pivot bracket to remove from studs.
3.Remove 5 nuts securing blower motor assembly
to volute housing.
4.Disconnect harness connector and remove
blower motor from volute housing.
5.Release circlip and withdraw impeller from motor
shaft.
6.Remove 3 nuts securing blower motor to
mounting plate.
7.Remove blower motor.
8.Examine components for signs of wear and
renew as necessary.
Refit
9.Apply Bostik 1261 adhesive to mating faces of
mounting plate and blower motor.
10.Fit blower motor to mounting plate and secure
with 3 nuts. Ensure rubber mountings are
correctly fitted.
11.Fit impeller to motor shaft and secure with circlip.
12.Position blower motor assembly in volute
housing and secure with 5 nuts. Fit angled
bracket to lower fixing.
13.Reconnect harness plug to resistor harness and
fit angled bracket to heater unit.
14.Fit heater unit
See Heater unit.HEATER MATRIX
Service repair no - 80.20.29
Remove
1.Remove heater unit
See Heater unit.
2.Remove 2 nuts securing angled bracket to
heater unit. Pivot bracket to remove from studs.
3.Remove 14 screws and detach two matrix
retaining plates from heater unit base.
4.Remove 9 screws securing matrix top retaining
plate.
5.Withdraw heater matrix through top of heater
unit casing.

HEATING AND VENTILATION
3
REPAIR Refit
6.Fit foam rubber to heater matrix casing.
7.Position matrix in heater unit casing.
8.Check that both vent flaps operate correctly
without sticking.
9.Secure matrix top retaining plate.
10.Secure matrix bottom retaining plates.
11.Fit heater unit
See Heater unit.RESISTOR UNIT
Service repair no - 80.20.17
Remove
1.Remove heater unit
See Heater unit.
2.Drill out 4 rivets securing resistor mounting plate
to top of volute housing.
3.Remove resistor and disconnect blower motor
plug from harness.
Refit
4.Apply Bostik adhesive to resistor mounting plate
and rivet to volute housing.
5.Reconnect blower harness motor plug.
6.Fit heater unit
See Heater unit.

80HEATING AND VENTILATION
4
REPAIR HEATER CONTROL CABLE - TEMPERATURE
CONTROL
Service repair no - 80.10.05
Remove
1.Disconnect battery.
2.Remove 4 screws securing instrument panel to
fascia cowl.
3.Pull instrument panel away from fascia and
disconnect speedometer cable to give easier
access to control cable at bulkhead.
4.Remove retaining screws and pull off air
distribution and temperature control lever knobs.
5.Remove 3 screws and detach side cover,
complete with control lever assembly.
6.Remove 2 screws securing control lever
assembly to side cover and remove cover. Note
plastic screw spacers fitted between cover and
control lever assembly and retain.
7.Remove small bolt and release outer cable
retaining clip.
8.Slacken grub screw and release inner cable from
clevis.
9.From inside engine compartment, release outer
cable retaining clip at heater unit.
10.Slacken trunnion fixing and release inner cable
from heater unit flap lever.
11.Release 2 retaining clips securing control cables
to engine bulkhead and heater hoses.
12.Pull control cable through bulkhead grommet
and remove from vehicle.
Refit
13.Fit new control cable to heater flap lever trunnion
with approximately 10 mm of inner cable
protruding from trunnion. Fully tighten trunnion.
14.Secure outer cable with retaining clip.
15.Route control cable through sealing grommet
and along inside of engine bulkhead to fascia
panel.

HEATING AND VENTILATION
5
REPAIR 16.Secure control cables to engine bulkhead and
heater hoses with retaining clips.
17.With control lever in closed position, fit inner
cable to lever clevis and fully tighten clevis grub
screw.
18.Fit outer cable retaining clip and fully tighten
securing bolt.
19.Fit side cover to control lever assembly. Ensure
fixing screw spacers are positioned between
cover and lever assembly.
20.Fit side cover to fascia.
21.Fit control lever knobs.
22.Reconnect speedometer cable and fit instrument
panel.
23.Reconnect battery.