
from the system back into the new A/C compressor.
Refer to the reclaim/recycling equipment manufactur-
ers instructions.
SERVICE PORT VALVE CORE
DESCRIPTION
A/C SERVICE PORT VALVE CORES
The low side valve is located on the suction line
near the A/C compressor. The low side A/C service
port valve core is a serviceable item. The high side
A/C service port valve core is located on the liquid
line fitting attached to the top of the receiver/drier.
The high side A/C service port valve core is not a sep-
arate serviceable item. If the high side service port
valve core is faulty or damaged, the front section of
the liquid line will require replacement.
REMOVAL
WARNING: REFER TO THE APPLICABLE WARN-
INGS AND CAUTIONS FOR THIS SYSTEM BEFORE
PERFORMING THE FOLLOWING OPERATION (Refer
to 24 - HEATING & AIR CONDITIONING/PLUMBING -
FRONT - WARNING - A/C PLUMBING) and (Refer to
24 - HEATING & AIR CONDITIONING/PLUMBING -
FRONT - CAUTION - A/C PLUMBING).
(1) Recover the refrigerant from the refrigerant
system (Refer to 24 - HEATING & AIR CONDITION-
ING/PLUMBING - FRONT/REFRIGERANT - STAN-
DARD PROCEDURE - REFRIGERANT
RECOVERY).
(2) Using a standard Schrader-type valve core tool,
remove the valve core from the low side A/C service
port located on the suction line.
(3) Install a plug in or tape over the opened low
side A/C service port.
INSTALLATION
(1) Lubricate the low side A/C service port valve
core with clean refrigerant oil prior to installation.
Use only refrigerant oil of the type recommended for
the compressor in the vehicle.
(2) Remove the tape or plug from the A/C service
port located on the suction line near the A/C com-
pressor.
(3) Using a standard Schrader-type valve core tool,
install and tighten the replacement valve core into
the low side A/C service port.
CAUTION: A valve core that is not fully seated in
the A/C service port can result in damage to the
valve during refrigerant system evacuation and
charge. Such damage may result in a loss of sys-tem refrigerant while uncoupling the charge adapt-
ers.
(4) Evacuate the refrigerant system (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
FRONT/REFRIGERANT - STANDARD PROCE-
DURE - REFRIGERANT SYSTEM EVACUATE).
(5) Charge the refrigerant system (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
FRONT/REFRIGERANT - STANDARD PROCE-
DURE - REFRIGERANT SYSTEM CHARGE).
(6) Reinstall the protective cap onto the A/C ser-
vice port.
SUCTION LINE
REMOVAL
WARNING: REFER TO THE APPLICABLE WARN-
INGS AND CAUTIONS FOR THIS SYSTEM BEFORE
PERFORMING THE FOLLOWING OPERATION (Refer
to 24 - HEATING & AIR CONDITIONING/PLUMBING -
FRONT - WARNING - A/C PLUMBING) and (Refer to
24 - HEATING & AIR CONDITIONING/PLUMBING -
FRONT - CAUTION - A/C PLUMBING).
NOTE: The front suction line includes the low side
service port on a section of tubing located near the
A/C compressor. On models equipped with the
optional rear A/C system, the front suction line also
includes a suction line hose and tube extension
that connects the front suction line to the suction
line for the rear A/C system.
(1) Recover the refrigerant from the refrigerant
system (Refer to 24 - HEATING & AIR CONDITION-
ING/PLUMBING - FRONT/REFRIGERANT - STAN-
DARD PROCEDURE - REFRIGERANT
RECOVERY).
(2) Disconnect and isolate the battery negative
cable.
(3) Remove the air cleaner top cover and snorkel
from the air cleaner housing located on the right side
of the engine compartment.
(4) Disconnect the drain tube from the wiper mod-
ule drain on the right side of the engine compart-
ment.
(5) Remove the nut that secures the suction line
fitting to the top of the A/C compressor.
(6) Disconnect the suction line fitting from the
compressor suction port.
(7) Remove the O-ring seal from the suction line
fitting and discard.
(8) Install plugs in, or tape over the opened suc-
tion line fitting and the compressor suction port.
24 - 94 PLUMBING - FRONTRS
REFRIGERANT OIL (Continued)

(9) Remove the retainer that secures the suction
line routing clip to the receiver/drier mounting
bracket on the side of the right front strut tower in
the engine compartment (Fig. 28).
(10) Remove the nut that secures the suction line
and liquid line fittings to the expansion valve.
(11) Disconnect the suction line and liquid line fit-
tings from the expansion valve.
(12) Remove the seals from the suction line and
liquid line fittings and discard.
(13) Install plugs in, or tape over the opened suc-
tion line and liquid line fittings and both expansion
valve ports.
(14) Remove the suction line from the retaining
bracket located at the top of the dash panel.
(15) If the vehicle is equipped with the optional
rear air conditioner, go to Step 16. If the vehicle does
not have the optional rear air conditioner, go to Step
22.
(16) Raise and support the vehicle.
(17) Cut the tie strap located just forward of the
connections between the underbody plumbing and
the engine compartment plumbing for the rear
heater and air conditioner (Fig. 29).
(18) Disconnect the suction line extension fitting
from the underbody suction line fitting for the rear
air conditioner.(19) Remove the O-ring seal from the underbody
suction line fitting and discard.
(20) Install plugs in, or tape over the opened suc-
tion line fittings.
(21) Lower the vehicle.
(22) Remove the suction line from the engine com-
partment.
INSTALLATION
(1) Position the suction line into the engine com-
partment.
(2) Remove the tape or plugs from the suction line
and liquid line fittings and both expansion valve
ports.
(3) Lubricate new rubber O-ring seals with clean
refrigerant oil and install them on the suction line
and liquid line fittings.
(4) Reconnect the liquid line and suction line fit-
tings to the expansion valve.
(5) Install the nut that secures the suction line
and liquid line fittings to the expansion valve.
Tighten the nut to 23 N´m (17 ft. lbs.).
(6) Install the retainer that secures the suction
line routing clip to the receiver/drier mounting
bracket on the side of the right front strut tower in
the engine compartment.
(7) Remove the tape or plugs from the compressor
suction port and the suction line fitting.
(8) Lubricate a new rubber O-ring seal with clean
refrigerant oil and install it on the suction line fit-
ting.
(9) Install a new dual plan seal and reconnect the
suction line fitting to the compressor suction port.
Fig. 28 Suction Line - LHD Shown, RHD Typical
1 - A/C EXPANSION VALVE
2 - SUCTION LINE EXTENSION (REAR A/C ONLY)
3 - NUT
4 - RETAINING CLIP
5 - SUCTION LINE
Fig. 29 Underbody A/C Line Connections
1 - SUCTION LINE EXTENSION
2 - LIQUID LINE EXTENSION
3 - RETAINER STRAP (3)
4 - HEATER TUBES
5 - UNDERBODY REFRIGERANT LINES
RSPLUMBING - FRONT24-95
SUCTION LINE (Continued)

(10) Install the nut that secures the suction line
fitting to the A/C compressor. Tighten the nut to 23
N´m (17 ft. lbs.).
(11) Reconnect the drain tube to the wiper module
drain on the right side of the engine compartment.
(12) Install the air cleaner top cover and snorkel
onto the air cleaner housing located on the right side
of the engine compartment.
(13) On RHD models, install the suction line into
the retaining bracket located at the top of the dash
panel.
(14) If the vehicle is equipped with the optional
rear air conditioner, go to Step 15. If the vehicle does
not have the optional rear air conditioner, go to Step
21.
(15) Raise and support the vehicle.
(16) Remove the tape or plugs from the suction
line extension fitting and the underbody suction line
fitting.
(17) Lubricate a new rubber O-ring seal with clean
refrigerant oil and install it on the underbody suction
line fitting.(18) Reconnect the suction line extension fitting to
the underbody suction line fitting. Tighten the fit-
tings to 23 N´m (17 ft. lbs.).
(19) Install a new tie strap just forward of the con-
nections between the underbody plumbing and the
engine compartment plumbing for the rear heater
and air conditioner.
(20) Lower the vehicle.
(21) Reconnect the battery negative cable.
(22) Evacuate the refrigerant system (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
FRONT/REFRIGERANT - STANDARD PROCE-
DURE - REFRIGERANT SYSTEM EVACUATE).
(23) Charge the refrigerant system (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
FRONT/REFRIGERANT - STANDARD PROCE-
DURE - REFRIGERANT SYSTEM CHARGE).
24 - 96 PLUMBING - FRONTRS
SUCTION LINE (Continued)

The rear A/C expansion valve cannot be adjusted
or repaired and, if faulty or damaged, it must be
replaced.
DIAGNOSIS AND TESTING - EXPANSION VALVE
WARNING: REFER TO THE APPLICABLE WARN-
INGS AND CAUTIONS FOR THIS SYSTEM BEFORE
PERFORMING THE FOLLOWING OPERATION.
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - FRONT - WARNING - A/C PLUMBING)
and (Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - FRONT - CAUTION - A/C PLUMBING).
NOTE: The expansion valve should only be tested
following testing of the compressor.
NOTE: Liquid CO
2is required to test the expansion
valve. This material is available from most welding
supply facilities. Liquid CO
2is also available from
companies which service and sell fire extinguish-
ers.
When testing the expansion valve, the work area
and the vehicle temperature must be 21É to 27É C
(70É to 85É F). To test the expansion valve:
(1) Connect a charging station or manifold gauge
set to the refrigerant system service ports. Verify the
refrigerant charge level.
(2) Close all doors, windows and vents to the pas-
senger compartment.
(3) Set the heater-air conditioner controls so that
the compressor is operating, the temperature control
is in the highest temperature position, the mode door
is directing the output to the floor outlets, and the
blower is operating at the highest speed setting.
(4) Start the engine and allow it to idle at 1000
rpm. After the engine has reached normal operating
temperature, allow the passenger compartment to
heat up. This will create the need for maximum
refrigerant flow into the evaporator.
(5) If the refrigerant charge is sufficient, the dis-
charge (high pressure) gauge should read 965 to 1655
kPa (140 to 240 psi). The suction (low pressure)
gauge should read 140 kPa to 207 kPa (20 psi to 30
psi). If OK, go to Step 6. If not OK, replace the faulty
expansion valve.
WARNING: PROTECT THE SKIN AND EYES FROM
EXPOSURE TO LIQUID CO
2. PERSONAL INJURY
CAN RESULT.
(6) If the suction (low pressure) gauge reads
within the specified range, freeze the expansion valve
control head for 30 seconds using liquid CO
2or
another suitable super-cold material.Do not sprayR-134a or R-12 refrigerant on the expansion
valve control head for this test.The suction (low
pressure) gauge reading should drop by 10 psi. If OK,
go to Step 7 If not OK, replace the faulty expansion
valve.
(7) Allow the expansion valve control head to thaw.
The suction (low pressure) gauge reading should sta-
bilize at 140 kPa to 240 kPa (20 psi to 30 psi). If not
OK, replace the faulty expansion valve.
(8) When expansion valve testing is complete, test
the overall air conditioner performance (Refer to 24 -
HEATING & AIR CONDITIONING - DIAGNOSIS
AND TESTING - A/C PERFORMANCE TEST).
Remove all test equipment before returning the vehi-
cle to service.
REMOVAL
WARNING: REFER TO THE APPLICABLE WARN-
INGS AND CAUTIONS FOR THIS SYSTEM BEFORE
PERFORMING THE FOLLOWING OPERATION (Refer
to 24 - HEATING & AIR CONDITIONING/PLUMBING -
FRONT - WARNING - A/C PLUMBING), (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
FRONT - CAUTION - A/C PLUMBING), and (Refer to
24 - HEATING & AIR CONDITIONING/PLUMBING -
FRONT - WARNING - HEATER PLUMBING).
(1) Remove the rear HVAC housing from the vehi-
cle (Refer to 24 - HEATING & AIR CONDITIONING/
DISTRIBUTION/HVAC HOUSING - REMOVAL).
(2) Carefully remove the foam insulator wrap from
the rear expansion valve.
(3) Remove the rear evaporator line extension from
the expansion valve (Refer to 24 - HEATING & AIR
CONDITIONING/PLUMBING - REAR/EVAPORA-
TOR - REMOVAL - EVAPORATOR LINE EXTEN-
SION).
(4) Remove the two screws that secure the expan-
sion valve to the evaporator tube sealing plate.
(5) Remove the expansion valve from the evapora-
tor tubes.
(6) Remove the seals from the evaporator tube fit-
tings and discard.
(7) Install plugs in, or tape over the opened evap-
orator tube fittings and both expansion valve ports.
INSTALLATION
(1) Remove the tape or plugs from the rear A/C
evaporator tube fittings and both expansion valve
ports.
(2) Lubricate new rubber O-ring seals with clean
refrigerant oil and install them on the rear evapora-
tor tube fittings.
(3) Position the expansion valve onto the evapora-
tor tubes.
24 - 100 PLUMBING - REARRS
A/C EXPANSION VALVE (Continued)

(17) Cut the tie strap located just forward of the
connections between the underbody plumbing and
the engine compartment plumbing for the rear heat-
er-A/C system (Fig. 8).
(18) Disconnect the front liquid line extension fit-
ting from the underbody liquid line fitting for the
rear air conditioner.
(19) Remove the O-ring seal from the underbody
liquid line fitting and discard.
(20) Install plugs in, or tape over the opened liquid
line fittings.
(21) Lower the vehicle.
(22) Remove the liquid line from the engine com-
partment.
INSTALLATION
(1) Position the rear section of the front liquid line
into the engine compartment.
(2) Remove the tape or plugs from the suction line
and liquid line fittings and both expansion valve
ports.
(3) Lubricate new rubber O-ring seals with clean
refrigerant oil and install them on the suction line
and liquid line fittings.
(4) Reconnect the liquid line and suction line fit-
tings to the expansion valve.
(5) Install the nut that secures the suction line
and liquid line fittings to the expansion valve.
Tighten the nut to 23 N´m (17 ft. lbs.).(6) Remove the tape or plugs from the liquid line
rear section fitting for the receiver/drier and the
receiver/drier outlet port.
(7) Lubricate a new rubber O-ring seal with clean
refrigerant oil and install it on the liquid line fitting.
(8) Reconnect the liquid line fitting to the receiver/
drier outlet port on the top of the receiver/drier.
(9) Install the bolt that secures the liquid line fit-
ting to the receiver/drier. Tighten the bolt to 11 N´m
(97 in. lbs.).
(10) If equipped, reinstall the A/C ground strap
eyelet terminal connector onto the weld stud on the
top of the right front strut tower (if equipped).
(11) If equipped, install the nut that secures the
A/C ground strap to the weld stud. Tighten the nut
to 12 N´m (106 in. lbs.)
(12) Install the A/C pressure transducer (Refer to
24 - HEATING & AIR CONDITIONING/CONTROLS/
A/C PRESSURE TRANSDUCER - INSTALLATION).
(13) Reconnect the drain tube to the wiper module
drain on the right side of the engine compartment.
(14) Reinstall the air cleaner housing into the
right side of the engine compartment.
(15) Raise and support the vehicle.
(16) Remove the tape or plugs from the liquid line
rear section extension fitting and the underbody liq-
uid line fitting.
(17) Lubricate a new rubber O-ring seal with clean
refrigerant oil and install it on the underbody liquid
line fitting.
(18) Reconnect the liquid line rear section exten-
sion fitting to the underbody liquid line fitting.
Tighten the fittings to 23 N´m (17 ft. lbs.).
(19) Install a new tie strap just forward of the con-
nections between the underbody plumbing and the
engine compartment plumbing for the rear heater-
A/C system.
(20) Lower the vehicle.
(21) Reconnect the battery negative cable.
(22) Evacuate the refrigerant system (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
FRONT/REFRIGERANT - STANDARD PROCE-
DURE - REFRIGERANT SYSTEM EVACUATE).
(23) Charge the refrigerant system (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
FRONT/REFRIGERANT - STANDARD PROCE-
DURE - REFRIGERANT SYSTEM CHARGE).
Fig. 8 Underbody A/C Line Connections
1 - SUCTION LINE EXTENSION
2 - LIQUID LINE EXTENSION
3 - RETAINER STRAP (3)
4 - HEATER TUBES
5 - UNDERBODY REFRIGERANT LINES
RSPLUMBING - REAR24 - 105
LIQUID LINE (Continued)

(18) Install plugs in, or tape over the opened suc-
tion line fittings.
(19) Lower the vehicle.
(20) Remove the suction line from the engine com-
partment.
INSTALLATION
(1) Position the suction line into the engine com-
partment.
(2) Remove the tape or plugs from the suction line
and liquid line fittings and both expansion valve
ports.
(3) Lubricate new rubber O-ring seals with clean
refrigerant oil and install them on the suction line
and liquid line fittings.
(4) Reconnect the liquid line and suction line fit-
tings to the expansion valve.
(5) Install the nut that secures the suction line
and liquid line fittings to the front expansion valve.
Tighten the nut to 23 N´m (17 ft. lbs.).
(6) Engage the retainer that secures the suction
line routing clip to the receiver/drier mounting
bracket on the side of the right front strut tower in
the engine compartment.
(7) Remove the tape or plugs from the compressor
suction port and the suction line fitting.
(8) Lubricate a new rubber O-ring seal with clean
refrigerant oil and install it on the suction line fit-
ting.
(9) Reconnect the suction line fitting to the com-
pressor suction port.
(10) Install the nut that secures the suction line
fitting to the A/C compressor. Tighten the nut to 23
N´m (17 ft. lbs.).
(11) Reconnect the drain tube to the wiper module
drain on the right side of the engine compartment.
(12) Reinstall the air cleaner top cover and snorkel
onto the air cleaner housing located on the right side
of the engine compartment.
(13) Reconnect the battery negative cable.
(14) Raise and support the vehicle.
(15) Remove the tape or plugs from the suction
line extension fitting and the underbody suction line
fitting.(16) Lubricate a new rubber O-ring seal with clean
refrigerant oil and install it on the underbody suction
line fitting.
(17) Reconnect the suction line extension fitting to
the underbody suction line fitting. Tighten the fitting
to 23 N´m (17 ft. lbs.).
(18) Install a new tie strap just forward of the con-
nections between the underbody plumbing and the
engine compartment plumbing for the rear heater
and air conditioner.
(19) Lower the vehicle.
(20) Evacuate the refrigerant system (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
FRONT/REFRIGERANT - STANDARD PROCE-
DURE - REFRIGERANT SYSTEM EVACUATE).
(21) Charge the refrigerant system (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
FRONT/REFRIGERANT - STANDARD PROCE-
DURE - REFRIGERANT SYSTEM CHARGE).
UNDERBODY LINES
DESCRIPTION
The underbody heater-A/C plumbing is used only
on models with the optional rear heater-A/C system
(Fig. 11). The underbody suction line, liquid line, and
heater tubes can each be serviced separately.
OPERATION
The rear heater and A/C lines are all serviced as
individual pieces. When disconnecting any line or
block ensure that the area around it is clean of any
contaminations that can get in to the system (Fig.
12), (Fig. 13), (Fig. 15), (Fig. 14) and (Fig. 16).
Any kinks or sharp bends in the rear heater-A/C
unit plumbing will reduce the capacity of the entire
heating and air conditioning system. Kinks and
sharp bends reduce the system flow. High pressures
are produced in the refrigerant system when the air
conditioning compressor is operating. High tempera-
ture coolant is present in the heater plumbing when
the engine is operating. Extreme care must be exer-
cised o make sure that each of the plumbing connec-
tions is pressure-tight and leak free.
RSPLUMBING - REAR24 - 107
SUCTION LINE (Continued)

(16) Place the underbody refrigerant lines on a
workbench and remove the nylon wedge securing the
underbody refrigerant lines to the underbody refrig-
erant line sealing plate (Fig. 21).
INSTALLATION
INSTALLATION - REAR HEATER LINES
(1) Position the rear heater underbody tubes to the
vehicle.
CAUTION:
DO NOT apply excessive pressure on heater tubes
or connections when removing heater hoses.
Excessive pressure may damage or deform the
tubes, causing an engine coolant leak.
(2) Connect the front underbody heater inlet and
return hose by carefully twisting the hoses back and
forth on the underbody tubes, while gently pushing
them onto the end of the tubes.
(3) Using spring tension clamp pliers, compress
and slide the clamps that secure each end of the
heater hose over the tubes. Release the clamp when
it is over the tube.
(4) Install the three retaining straps that secure
the rear heater underbody tubes to the vehicle under-
body.
(5) Connect the rear underbody heater tube quick
connections to the rear heater core extension tubes.
(6) Lower the vehicle.
(7) Refill the engine cooling system (Refer to 7 -
COOLING - STANDARD PROCEDURE - COOLING
SYSTEM REFILL).(8) Lower vehicle.
(9) Fill cooling system (Refer to 7 - COOLING -
STANDARD PROCEDURE).
INSTALLATION - UNDERBODY REFRIGERANT
LINES
(1) Install the nylon wedges that secure the under-
body refrigerant lines to the underbody refrigerant
line sealing plate.
(2) Position the underbody refrigerant lines to the
vehicle underbody.
(3) Install the ABS harness into the flex hose
clamps.
(4) Remove the tape or plugs from the underbody
liquid line and suction line fittings and both ports in
the rear evaporator extension line sealing plate that
extends through the rear floor panel behind the right
rear wheel housing.
(5) Lubricate new rubber O-ring seals with clean
refrigerant oil and install them on the liquid line and
suction line fittings.
(6) Reconnect the underbody refrigerant line seal-
ing plate to the evaporator extension line sealing
plate.
(7) Install the bolt that secures the underbody
refrigerant line sealing plate to the evaporator exten-
sion line sealing plate. Tighten the bolt to 23 N´m (17
ft. lbs.).
(8) Remove the tape or plugs from the suction line
extension fitting and the underbody suction line fit-
ting.
(9) Lubricate a new rubber O-ring seal with clean
refrigerant oil and install it on the underbody suction
line fitting.
(10) Reconnect the suction line extension fitting to
the underbody suction line fitting. Tighten the fitting
to 23 N´m (17 ft. lbs.).
(11) Remove the tape or plugs from the liquid line
rear section extension fitting and the underbody liq-
uid line fitting.
(12) Lubricate a new rubber O-ring seal with clean
refrigerant oil and install it on the underbody liquid
line fitting.
(13) Reconnect the liquid line rear section exten-
sion fitting to the underbody liquid line fitting.
Tighten the fittings to 23 N´m (17 ft. lbs.).
(14) Lower the vehicle.
(15) Evacuate the refrigerant system (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
FRONT/REFRIGERANT - STANDARD PROCE-
DURE - REFRIGERANT SYSTEM EVACUATE).
(16) Charge the refrigerant system (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
FRONT/REFRIGERANT - STANDARD PROCE-
DURE - REFRIGERANT SYSTEM CHARGE).
Fig. 21 Underbody Line Wedges
1 - O-RING (2)
2 - LIQUID LINE
3 - NYLON WEDGE (2)
4 - SEALING PLATE
5 - VISE
6 - SUCTION LINE
RSPLUMBING - REAR24 - 111
UNDERBODY LINES (Continued)

CABIN HEATER
TABLE OF CONTENTS
page page
CABIN HEATER
DESCRIPTION........................112
OPERATION
OPERATION - MANUAL TEMPERATURE
CONTROL SYSTEM...................112
OPERATION - AUTOMATIC TEMPERATURE
CONTROL SYSTEM...................112
DIAGNOSIS AND TESTING - DIESEL
SUPPLEMENTAL CABIN HEATER........113
AIR INTAKE PIPE
REMOVAL............................113
INSTALLATION........................114
EXHAUST TUBE
REMOVAL............................114
INSTALLATION........................115FUEL DOSING PUMP
DESCRIPTION........................115
OPERATION..........................115
REMOVAL............................115
INSTALLATION........................116
FUEL LINE
STANDARD PROCEDURE - CLEANING.....117
REMOVAL............................117
INSTALLATION........................118
HEATER UNIT
REMOVAL............................118
INSTALLATION........................119
SUPPLEMENTAL DIESEL HEATER WIRING
REMOVAL............................119
INSTALLATION........................119
CABIN HEATER
DESCRIPTION
Vehicles equipped with the diesel engine are also
equipped with a supplemental cabin heater. This
cabin heater is mounted under the vehicle and oper-
ates similar to an oil fired furnace. The heater burns
small amounts of fuel to provide additional heat to
the coolant. Coolant is routed from the engine, to the
supplemental cabin heater and then to the front
heater core. This provides additional heat to the pas-
senger compartment. The supplemental cabin heater
system is interfaced to the vehicles on-board com-
puter systems and DRBIIItdiagnostics.
The supplemental cabin heater has an electronic
control module that monitors the heat output of the
heater. The cabin heater operates at full load (5 kW),
half load or idle mode (no additional heat) depending
on engine coolant temperature.
OPERATION
OPERATION - MANUAL TEMPERATURE
CONTROL SYSTEM
The supplemental cabin heater is activated via the
temperature slide control or knob on the A/C-heater
control when equipped with the manual temperature
control (MTC) system. If the slide control or knob is
moved to or above the upper set point the cabin
heater is activated. The cabin heater can operate in a
full or partial load range as well as an idle mode alldependent on the engine coolant temperature. The
cabin heater will also turn off if the A/C-heater tem-
perature control is lowered to less than the lower set
point. The cabin heater can take up to three minutes
to completely shut down when either the heater tem-
perature is set below the lower set point or the vehi-
cle ignition is shut down.
NOTE: Do not apply a strong vacuum source such
as a garage ventilation system directly on the sup-
plemental cabin heater exhaust line. Too strong of a
vacuum can prevent the supplemental cabin heater
from starting. If required, place the vacuum source
at least 75 mm (3 in.) away from the exhaust line.
The supplemental cabin heater only operates when
the engine is running, the mileage exceeds 8 kilome-
ter (5 mph) and the fuel tank volume exceeds 1/8 of a
tank. The supplemental heater control module moni-
tors blower speed and combustion during its start-up.
The cabin heater should operate if the coolant tem-
perature is below 40É C (104É F).
OPERATION - AUTOMATIC TEMPERATURE
CONTROL SYSTEM
The automatic temperature control (ATC) system
will activate the supplemental cabin heater based on
engine coolant temperature and interior component
settings. The cabin heater can operate in a full or
partial load range as well as an idle mode all depen-
dent on the engine coolant temperature. The cabin
heater will also turn off if the A/C-heater tempera-
ture control is lowered to less than the lower set
24 - 112 CABIN HEATERRS