Page 1857 of 1938

REAR HEATING AND AIR CONDITIONING SYSTEM
INDEX
page page
GENERAL INFORMATION
INTRODUCTION......................... 41
DESCRIPTION AND OPERATION
REAR BLOWER RESISTOR BLOCK.......... 41
REAR HEATER AND A/C LINES............. 41
SYSTEM OPERATION.................... 41
DIAGNOSIS AND TESTING
DIAGNOSTIC PROCEDURES............... 43
REMOVAL AND INSTALLATION
AIR DISTRIBUTION DUCT-A/C.............. 43
AIR DISTRIBUTION DUCT-HEATER.......... 43
EVAPORATOR AND EXPANSION VALVE...... 44MODE DOOR ACTUATOR................. 49
MODE DOOR........................... 49
REAR AIR CONDITIONING LINES........... 45
REAR HEATER A/C AIR OUTLETS........... 45
REAR HEATER A/C BLOWER MOTOR........ 46
REAR HEATER A/C UNIT.................. 46
REAR HEATER CORE.................... 48
REAR HEATER LINES.................... 49
REAR HEATER-A/C AUXILIARY CONDENSER . . 45
REAR HEATER-A/C CONTROL ILLUMINATION
BULB............................... 46
GENERAL INFORMATION
INTRODUCTION
For proper operation of the rear heating A/C sys-
tem, refer to Owner's Manual supplied with the vehi-
cle.
DESCRIPTION AND OPERATION
REAR BLOWER RESISTOR BLOCK
The rear blower motor resistor is not serviceable
separately. The resistor is integral to the blower
motor. If resistor is faulty, it is necessary to replace
the complete blower motor.
REAR HEATER AND A/C LINES
The rear heater and A/C lines are all serviced as
individual pieces. When disconnecting any line orblock ensure that the area around it is clean of any
contaminations that can get in to the system (Fig. 1),
(Fig. 2), (Fig. 4), (Fig. 3) and (Fig. 5).
SYSTEM OPERATION
The auxiliary rear heating-air/conditioning unit is
located in the right rear quarter panel. The rear
heater A/C control operates in conjunction with the
front heater A/C control. A four position two speed
blower (override) switch is located on the front
Heater A/C control panel (Fig. 6). The operator can
use the rear heater A/C blower switch to operate the
blower, regardless of the rear control setting. In the
OFF position, the rear control will not function. In
the ON (RR) position, the rear control will function
normally providing three speeds (Fig. 7). The mode
setting is controlled by the front A/C control panel.
Fig. 1 Rear Heater and A/C Lines
NSHEATING AND AIR CONDITIONING 24 - 41
Page 1858 of 1938

Air from inside the vehicle is drawn into the air
intake grille in the right rear quarter trim panel. The
air enters the blower and is pushed through the
heater core and A/C evaporator coil. The air direc-
tion, floor or overhead, is determined by the position
of the driver's temperature control lever on the front
HVAC system control. If the temperature control
lever is below 20% heat, the auxiliary HVAC system
airflow will come from the overhead air outlets. In
between 20% and 80%, the airflow will remain in the
last position selected. In other words, if the driver
started out in full heat and then adjusted their tem-
perature lever to 30% heat as they became comfort-
able, the rear air would come out the floor outlets the
whole time.
Fig. 2 Front Lines Connected to Rear Lines
Fig. 3 Rear Heater Hose Connection
Fig. 4 Rear heater hose quick connects
Fig. 5 Rear A/C Block Connection
Fig. 6 A/C Control Panel
24 - 42 HEATING AND AIR CONDITIONINGNS
DESCRIPTION AND OPERATION (Continued)
Page 1859 of 1938

DIAGNOSIS AND TESTING
DIAGNOSTIC PROCEDURES
When diagnosing electrical problems in the auxil-
iary rear heater or rear A/C system, refer to Group
8W, Wiring Diagrams.
When diagnosing problems in the auxiliary sys-
tems, refer to diagnostic sections for front heater A/C.
REMOVAL AND INSTALLATION
AIR DISTRIBUTION DUCT-A/C
REMOVAL
(1) Remove quarter trim panel, D-pillar, and head-
liner (Fig. 8). Refer to Group 23, Body.
(2) Remove screws securing D-pillar duct to quar-
ter panel. Pull duct up and away from unit.
(3) Remove screws securing duct to rear header
(Fig. 9).
(4) Remove screws securing duct to right and left
rails (Fig. 10).
INSTALLATION
For installation, reverse the above procedures.
AIR DISTRIBUTION DUCT-HEATER
REMOVAL
(1) Remove quarter trim panel and D-pillar (Fig.
8) and (Fig. 11). Refer to Group 23, Body.
(2) Remove screws securing lower heat duct to
housing.
INSTALLATION
For installation, reverse the above procedures.
Fig. 7 Rear Blower Switch
Fig. 8 Quarter Trim Panel
Fig. 9 Rear Crossover Duct
Fig. 10 Upper A/C Duct
NSHEATING AND AIR CONDITIONING 24 - 43
DESCRIPTION AND OPERATION (Continued)
Page 1860 of 1938

EVAPORATOR AND EXPANSION VALVE
NOTE: Special effort must be used to keep all
R-134a system components moisture-free. Moisture
in the oil is very difficult to remove and will cause a
reliability problem with the compressor.
REMOVAL
WARNING: THE REFRIGERANT SYSTEM MUST BE
EMPTY BEFORE PERFORMING THE FOLLOWING
OPERATION. THE ENGINE COOLING SYSTEM
MUST ALSO BE RELIEVED OF ALL PRESSURE.
(1) Remove right quarter trim panel and D-pillar
trim. Refer to Group 23, Body.
(2) Remove fan A/C distribution duct.
(3) Remove rear A/C unit.
(4) Remove blower scroll.
(5) Remove evaporator cover (Fig. 12).
(6) Remove the nut that mounts the refrigerant
plumbing block to the expansion valve (Fig. 13).
(7) Carefully pull the evaporator and expansion
valve straight out of unit (Fig. 14). Do not scratch
the sealing surfaces with the plumbing extension
tube pilots.
(8) Remove and discard the O-rings between the
plumbing extension and the expansion valve.
(9) Cover the plumbing extension sealing surface
to prevent contamination.
(10) Bring evaporator and expansion valve to a
clean work space.
(11) Remove two 1/4-20 Torx Head screws.
(12) Remove expansion valve.
(13) Measure and record the amount of residual oil
from the removed evaporator.
INSTALLATION
(1) Replace the O-rings.(2) Hold expansion valve against evaporator seal-
ing plate (do not scratch the sealing surface). Install
two screws and tighten to 1163 N´m (100630 inch
pounds) torque.
Fig. 11 Rear Heat-A/C UnitFig. 12 Evaporator Cover
Fig. 13 Expansion Valve
Fig. 14 Evaporator Removal
24 - 44 HEATING AND AIR CONDITIONINGNS
REMOVAL AND INSTALLATION (Continued)
Page 1861 of 1938

CAUTION: Do not damage the evaporator insulation
liner during installation.
(3) Carefully install the evaporator and expansion
valve straight into the unit. Do not scratch the seal-
ing surfaces with the plumbing extension tube pilots.
(4) Determine the amount of old refrigerant oil
drained from the evaporator. Add this amount (of
clean refrigerant oil) back into the system.
(5) Carefully align the expansion valve onto the
pilot tubes of the plumbing extension (do not scratch
the sealing surface). Install the bolt through the
plumbing plate into the unit sealing plate. Tighten
bolts to 2363 N´m (200630 inch pounds) torque.
(6) Install evaporator cover and blower scroll.
(7) Install quarter trim panel, evacuate/charge sys-
tem, and perform the performance test.
REAR AIR CONDITIONING LINES
WARNING: THE REFRIGERATION SYSTEM MUST
BE COMPLETELY EMPTY BEFORE PROCEEDING
WITH THIS OPERATION.
REMOVAL
(1) Hoist vehicle
(2) Remove compression fittings to the suction and
liquid lines located on the right, outboard side of the
underbody, rearward of the front crossmember. (Fig.
2)
(3) remove (1) bolt securing a/c lines to block
located on the right, outboard side of the underbody,
rearward of the rear wheel and tire. (Fig. 5)
(4) Remove (3) straps securing underbody lines.
(Fig. 1)
(5) Separate and remove a/c lines from vehicle.
INSTALLATION
(1) Before installation, replace all O-rings and gas-
kets. Coat all sealing surfaces with approved wax-
free refrigerant oil. Then, reverse the above
procedures.
(2) Evacuate and recharge system.
REAR HEATER A/C AIR OUTLETS
REMOVAL
Separate barrel from bezel by pulling outward.
INSTALLATION
For installation, push the outlet firmly into the
opening until it locks into place.
REAR HEATER-A/C AUXILIARY CONDENSER
If vehicle is equipped with a 3.3L or 3.8L engine
with rear heater and air conditioning, it will be
equipped with an auxiliary condenser. The auxiliarycondenser is mounted on the primary condenser in
front of the radiator. Both condenser must be
removed as an assembly and then separated.
WARNING: THE REFRIGERATION SYSTEM MUST
BE COMPLETELY EMPTY BEFORE PROCEEDING
WITH THIS OPERATION.
NOTE: Special effort must be used to keep all
R-134a system components moisture-free. Moisture
in the oil is very difficult to remove and will cause a
reliability problem with the compressor.
The condenser assembly must first be removed
from vehicle. Refer to CONDENSER ASSEMBLY
removal and installation in this section for service
procedures.
REMOVAL
(1) After condenser assembly removal, place on
bench for disassembly.
(2) Remove (1) bolt to liquid line on auxiliary con-
denser.
(3) Remove (4) attaching bolts and separate auxil-
iary from primary condenser. (Fig. 15)
INSTALLATION
(1) Before installation, replace all O-rings and gas-
kets. Coat all sealing surfaces with approved wax-
free refrigerant oil. Then, reverse the above
procedures.
(2) Evacuate and recharge system.
Fig. 15 3.3L/3.8L REAR HEAT-A/C AUXILIARY
CONDENSER
NSHEATING AND AIR CONDITIONING 24 - 45
REMOVAL AND INSTALLATION (Continued)
Page 1862 of 1938

REAR HEATER A/C BLOWER MOTOR
REMOVAL
(1) Remove the right quarter trim panel and D-pil-
lar trim. Refer to Group 23, Body for service proce-
dures.
(2) Remove (5) screws securing the blower motor
housing to the rear of the HVAC housing (one screw
located on evaporator cover) (Fig. 16).
(3) Twist motor out of scroll housing.
(4) Disconnect blower motor wiring connector.
INSTALLATION
For installation, reverse the above procedures.
REAR HEATER-A/C CONTROL ILLUMINATION BULB
REMOVAL
(1) Remove rear heater-A/C control from trim
panel.
(2) On the back of control opposite from the wire
connectors, locate the bulb socket lug.
(3) Rotate the socket counterclockwise and pull the
socket from the control.
INSTALLATION
For installation, reverse the above procedures.
Refer to Group 8L, Lamps for bulb usage.
REAR HEATER A/C UNIT
NOTE: Special effort must be used to keep all
R-134a system components moisture-free. Moisture
in the oil is very difficult to remove and will cause a
reliability problem with the compressor.
REMOVAL
WARNING: ON VEHICLES EQUIPPED WITH REAR
A/C, THE REFRIGERANT SYSTEM MUST BE EMP-
TIED BEFORE PERFORMING THE FOLLOWING
OPERATION. THE ENGINE COOLING SYSTEM
MUST ALSO BE RELIEVED OF ALL PRESSURE.
(1) Using a refrigerant recovery machine, remove
refrigerant from the A/C system. Disconnect A/C
plumbing from rear heater A/C unit.
(2) Hoist vehicle.
(3) Remove A/C lines at lower floor pan flange
(Fig. 17).
(4) Remove (3) A/C unit floor mounting nuts (Fig.
18).
(5) Lower vehicle.
(6) Remove right quarter trim panel and D-pillar
trim (Fig. 8). Refer to Group 23, Body.
(7) Remove screws securing air distribution duct to
the rear wheel housing (Fig. 19).
Fig. 16 Blower Motor
Fig. 17 A/C Lines
Fig. 18 A/C Mounting
24 - 46 HEATING AND AIR CONDITIONINGNS
REMOVAL AND INSTALLATION (Continued)
Page 1863 of 1938
(8) Pinch off heater lines at heater core hookup
(Fig. 20).
(9) Remove heater hoses at heater core (Fig. 21).(10) Remove quarter trim panel mounting bracket
(Fig. 22).
(11) Remove blower motor wiring harness connec-
tor.
(12) Remove rear upper duct trim screw (Fig. 23).
(13) Remove (2) Heater-A/C housing mounting
bolts (Fig. 24).
(14) Pull up on upper A/C duct. Tilt A/C unit out-
ward (Fig. 25).
(15) Lift the unit enough to clear floor pan.
Remove unit from the vehicle.
INSTALLATION
For installation, reverse the above procedures.
Install new O-rings at refrigerant lines. Evacuate
and charge the refrigerant system. Fill the heater
core (Fig. 26). Test for leaks and overall performance.
Fig. 19 Lower Heater Duct
Fig. 20 Heater Core Lines
Fig. 21 Heater Hoses
Fig. 22 Trim Panel Mounting Bracket
Fig. 23 Upper Duct Trim
NSHEATING AND AIR CONDITIONING 24 - 47
REMOVAL AND INSTALLATION (Continued)
Page 1864 of 1938

NOTE: If the heater core was emptied and was not
prefilled, it is necessary to thermal cycle the vehicle
TWICE. The heater core is positioned higher than
the radiator fill cap. Therefore the heater core will
not gravity fill to level. To thermal cycle the vehicle,
it must be operated till the thermostat opens, then
turned off and allowed to cool. In order to verify
that the auxiliary unit is filled completely, the follow-
ing procedure can be used:
²Vehicle at room temperature.
²Engine is brought up to operating temperature.
²Front unit is OFF, temperature slides are at full
HEAT position.
²Engine is at idle.
²With rear blower motor ON HIGH.
²Discharge air temperature, measured at the
dual register located on the C-pillar base, is between
135É and 145É F.
REAR HEATER CORE
REMOVAL
(1) Remove the lower right quarter trim panel.
Refer to Group 23, Body.
(2) Isolate and disconnect lines from heater core
(Fig. 27).
(3) Remove heater core retaining screws.
(4) Carefully pull the heater core and tubes up and
straight out of the unit.
INSTALLATION
For installation, reverse the above procedures. Pre-
fill the heater core (Fig. 26). Test for leaks and over-
all performance.
Fig. 24 Mounting Bolts
Fig. 25 A/C Unit Replacement
Fig. 26 Filling Heater Core
Fig. 27 Heater Core Lines
24 - 48 HEATING AND AIR CONDITIONINGNS
REMOVAL AND INSTALLATION (Continued)