heating CHRYSLER VOYAGER 1996 Manual PDF

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)

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)

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)

(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)

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)

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
57ÉC to 62ÉC (135É and 145É F).
REAR HEATER LINES
REMOVAL
NOTE: Review Safety Precautions and Warnings
before proceeding with this operation.
(1) Partially drain engine cooling system. Refer to
Group 7, Engine Cooling.
(2) Loosen clamp at the front end of the hose
located at the right, outboard side of the underbody,
rearward of the front crossmember. (Fig. 2)
(3) Carefully rotate hose back and forth while tug-
ging slightly away from connector nipple. If the hose
will not come off, slice the hose at the connector nip-
ple and peel off heater hose. This method will require
heater hose replacement.
CAUTION: When removing hoses from outlet nip-
ples, do not use excessive force. Outlet nipples
may become damaged and leak engine coolant.
(4) Compress insert in rear heater hose quick con-
nection and pull downward on hose. (Fig. 4)(5) Remove (3) straps securing underbody lines.
(Fig. 1)
(6) Separate and remove rear heater lines from
vehicle.
INSTALLATION
For installation, reverse the above procedures.
MODE DOOR
REMOVAL
(1) Remove A/C unit.
(2) Place unit on bench.
(3) Remove heater core.
(4) Remove blower scroll.
(5) Remove evaporator cover.
(6) Remove A/C line to expansion valve mounting
nut.
(7) Carefully pull evaporator out of housing.
(8) Remove mode door actuator and gear exten-
sion.
(9) Remove Heater-A/C housing clips and screws.
(10) Separate housing halves.
(11) Remove mode door.
INSTALLATION
For installation, reverse the above procedures.
MODE DOOR ACTUATOR
REMOVAL
(1) Remove A/C unit.
(2) Place unit on bench.
(3) Remove mode door actuator connector.
(4) Remove mode door actuator mounting screws
and remove actuator.
INSTALLATION
For installation, reverse the above procedures.
NSHEATING AND AIR CONDITIONING 24 - 49
REMOVAL AND INSTALLATION (Continued)

HEATING AND AIR CONDITIONING
CONTENTS
page page
GENERAL INFORMATION
INTRODUCTION........................ 1
SAFETY PRECAUTIONS AND WARNINGS.... 2
DESCRIPTION AND OPERATION
A/C PRESSURE TRANSDUCER............ 2
A/C SERVICE PORTS.................... 2
AIR DISTRIBUTION DUCTS............... 2
COMPRESSOR......................... 2
COMPRESSOR HIGH-PRESSURE RELIEF
VALVE .............................. 3
CONDENSATE DRAIN.................... 3
ENGINE COOLING SYSTEM REQUIREMENTS . 3
EVAPORATOR PROBE................... 3
HANDLING TUBING AND FITTINGS........ 3
HVAC CONTROL MODULE................ 3
SIDE DOOR HEATER A/C OUTLETS........ 4
SIDE WINDOW DEMISTER............... 4
SYSTEM AIRFLOW..................... 4
SYSTEM OIL LEVEL..................... 4
DIAGNOSIS AND TESTING
A/C PERFORMANCE TEST............... 11
A/C PRESSURE TRANSDUCER........... 11
ACTUATOR CALIBRATION/DIAGNOSTICS AND
COOLDOWN TEST..................... 5
BLOWER MOTOR AND WHEEL ASSEMBLY . 12
COMPRESSOR CLUTCH/COIL............ 12
COMPRESSOR NOISE DIAGNOSIS........ 12
EXPANSION VALVE.................... 14
HEATER PERFORMANCE TEST........... 14
HVAC CONTROL DIAGNOSTIC CONDITIONS . 9
SYSTEM CHARGE LEVEL TEST........... 15SERVICE PROCEDURES
CHARGING REFRIGERANT SYSTEM....... 17
EVACUATING REFRIGERANT SYSTEM..... 17
R-134a REFRIGERANT.................. 16
STICKING HVAC CONTROL MODULE PUSH
BUTTONS.......................... 18
SYSTEM LEAK CHECKING............... 19
THERMOCOUPLE PROBE............... 18
REMOVAL AND INSTALLATION
A/C PRESSURE TRANSDUCER........... 19
A/C SERVICE PORTS................... 19
BLEND-AIR DOOR ACTUATOR........... 20
BLOWER MOTOR AND WHEEL ASSEMBLY . 20
BLOWER MOTOR RESISTOR BLOCK...... 21
BLOWER MOTOR WHEEL............... 22
COMPRESSOR (2.5L TURBO DIESEL)..... 22
CONDENSER ASSEMBLY................ 23
DISCHARGE LINE..................... 23
EVAPORATOR PROBE.................. 24
EXPANSION VALVE.................... 25
FILTER-DRIER ASSEMBLY............... 26
HEATER A/C UNIT HOUSING............. 26
HEATER CORE........................ 26
HEATER HOSES....................... 28
LIQUID LINE......................... 28
MODE DOOR ACTUATOR................ 29
RECIRC DOOR ACTUATOR.............. 30
SIDE WINDOW DEMISTER DUCTS........ 29
SUCTION LINE........................ 29
DISASSEMBLY AND ASSEMBLY
HEATER A/C UNIT RECONDITION......... 30
GENERAL INFORMATION
INTRODUCTION
The Heater, or Heater and Air Conditioning sys-
tems share many of the same components. This
group will deal with both systems together when
component function is common, and separately when
they are not.
For proper operation of the instrument panel con-
trols, refer to the Owner's Manual provided with the
vehicle.All vehicles are equipped with a common Heater
A/C unit housing assembly. When the vehicle has
only a heater system, the evaporator and recirculat-
ing air door are omitted.
An optional zone control HVAC unit is available.
This unit has dual blend-air doors that can be regu-
lated independently of each other. The temperature
setting can be different from driver's side to passen-
ger side.
NS/GSHEATING AND AIR CONDITIONING 24 - 1

SAFETY PRECAUTIONS AND WARNINGS
WARNING: WEAR EYE PROTECTION WHEN SER-
VICING THE AIR CONDITIONING REFRIGERANT
SYSTEM. SERIOUS EYE INJURY CAN RESULT
FROM EYE CONTACT WITH REFRIGERANT. IF EYE
CONTACT IS MADE, SEEK MEDICAL ATTENTION
IMMEDIATELY.
DO NOT EXPOSE REFRIGERANT TO OPEN
FLAME. POISONOUS GAS IS CREATED WHEN
REFRIGERANT IS BURNED. AN ELECTRONIC TYPE
LEAK DETECTOR IS RECOMMENDED.
LARGE AMOUNTS OF REFRIGERANT RELEASED
IN A CLOSED WORK AREA WILL DISPLACE THE
OXYGEN AND CAUSE SUFFOCATION.
THE EVAPORATION RATE OF REFRIGERANT AT
AVERAGE TEMPERATURE AND ALTITUDE IS
EXTREMELY HIGH. AS A RESULT, ANYTHING THAT
COMES IN CONTACT WITH THE REFRIGERANT
WILL FREEZE. ALWAYS PROTECT SKIN OR DELI-
CATE OBJECTS FROM DIRECT CONTACT WITH
REFRIGERANT. R-134a SERVICE EQUIPMENT OR
VEHICLE A/C SYSTEM SHOULD NOT BE PRES-
SURE TESTED OR LEAK TESTED WITH COM-
PRESSED AIR.
SOME MIXTURES OF AIR and R-134a HAVE BEEN
SHOWN TO BE COMBUSTIBLE AT ELEVATED
PRESSURES. THESE MIXTURES ARE POTENTIALLY
DANGEROUS AND MAY RESULT IN FIRE OR
EXPLOSION CAUSING INJURY OR PROPERTY
DAMAGE.
ANTIFREEZE IS AN ETHYLENE GLYCOL BASE
COOLANT AND IS HARMFUL IF SWALLOWED OR
INHALED. SEEK MEDICAL ATTENTION IMMEDI-
ATELY IF SWALLOWED OR INHALED. DO NOT
STORE IN OPEN OR UNMARKED CONTAINERS.
WASH SKIN AND CLOTHING THOROUGHLY AFTER
COMING IN CONTACT WITH ETHYLENE GLYCOL.
KEEP OUT OF REACH OF CHILDREN AND PETS.
DO NOT OPEN A COOLING SYSTEM WHEN THE
ENGINE IS AT RUNNING TEMPERATURE. PER-
SONAL INJURY CAN RESULT.
CAUTION: The engine cooling system is designed
to develop internal pressure of 97 to 123 kPa (14 to
18 psi). Allow the vehicle to cool a minimum of 15
minutes before opening the cooling system. Refer
to Group 7, Cooling System.
DESCRIPTION AND OPERATION
AIR DISTRIBUTION DUCTS
The air distribution ducts for the A/C, Heater,
Defroster, and Second Seating Air Distribution arenot serviceable in vehicle. The procedures for service
of these ducts are covered in Group 8E, Instrument
Panel and Gauges.
The only ducts that are serviceable in the vehicle
are the side window demister ducts and the ducts
that feed the front door outlets for the first rear pas-
senger(s) seating. To service the door ducts refer to
Group 23, Body.
A/C PRESSURE TRANSDUCER
The A/C Pressure Transducer (Fig. 1) monitors the
refrigerant gas pressure on the high side of the sys-
tem. The transducer is located on the liquid line. The
pressure transducer turns off the voltage to the com-
pressor clutch coil when refrigerant gas pressure
drops to levels that could damage the compressor.
The transducer also is used to adjust condenser fan
speeds and will turn off compressor at high refriger-
ant pressures. The pressure transducer is a sealed
factory calibrated unit. It must be replaced if defec-
tive. O-ring replacement is required whenever the
pressure transducer is serviced. Be sure to use the
O-ring specified for the transducer.
A/C SERVICE PORTS
The A/C service port valve cores are located within
the A/C lines. The High Side (Discharge) valve ser-
vice port is located on the liquid line near the right
strut tower. The Low Side (Suction) valve service
port is located on the suction line near the compres-
sor.
The High Side service port is a two piece port and
is serviceable. The Low Side service port is not ser-
viceable, and the suction line would have to be
replaced.
COMPRESSOR
The A/C compressor for the 2.5L Turbo Diesel, is
located on the front side of the engine block. It is
mounted to the engine block by four bolts. The com-
Fig. 1 A/C Pressure Transducer
24 - 2 HEATING AND AIR CONDITIONINGNS/GS
GENERAL INFORMATION (Continued)

pressor is driven off the back of the power steering
pump. A rubber flex coupling transfers the power from
the power steering pump to the compressor clutch.
COMPRESSOR HIGH-PRESSURE RELIEF VALVE
The High Pressure Relief Valve prevents damage
to the air conditioning system if excessive pressure
develops. Excessive pressure can be caused by con-
denser air flow blockage, refrigerant overcharge, or
air and moisture in the system.
The high pressure relief valve vents only a small
amount of refrigerant necessary to reduce system
pressure and then reseats itself. The majority of the
refrigerant is conserved in the system. The valve is
calibrated to vent at a pressure of 3450 to 4140 kPa
(500 to 600 psi). If a valve has vented a small
amount of refrigerant, it does not necessarily mean
the valve is defective.
The High Pressure Relief Valve is located on the
compressor manifold at the discharge passage.
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.
CONDENSATE DRAIN
Condensation from the evaporator housing is
drained through the dash panel and on to the
ground. This drain must be kept open to prevent
water from collecting in the bottom of the housing.
If the drain is blocked condensate cannot drain,
causing water to back up and spill into the passenger
compartment. It is normal to see condensate drain-
age below the vehicle.
ENGINE COOLING SYSTEM REQUIREMENTS
To maintain ample temperature levels from the
heating-A/C system, the cooling system must be in
proper working order. Refer to Group 0, Lubrication
and Maintenance or Group 7, Cooling System of this
manual.
The use of a bug screen is not recommended. Any
obstructions forward of the condenser can reduce the
effectiveness of the air conditioning system.
EVAPORATOR PROBE
The Evaporator probe is located on the HVAC. The
probe prevents evaporator freeze-up by signaling the
Powertrain Control Module to cycle the compressor
ON and OFF. The probe monitors the temperature of
the refrigerant after expansion.
The evaporator probe is inserted into the evapora-
tor between the coils. The probe is a sealed unit and
cannot be adjusted or repaired. It must be replaced if
found defective.
HANDLING TUBING AND FITTINGS
Kinks in the refrigerant tubing or sharp bends in
the refrigerant hose lines will greatly reduce the
capacity of the entire system. High pressures are pro-
duced in the system when it is operating. Extreme
care must be exercised to make sure that all connec-
tions are pressure tight. Dirt and moisture can enter
the system when it is opened for repair or replace-
ment of lines or components. The refrigerant oil will
absorb moisture readily out of the air. This moisture
will convert into acids within a closed system.
CAUTION: The system must be completely empty
before opening any fitting or connection in the
refrigeration system. Open fittings with caution
even after the system has been emptied. If any
pressure is noticed as a fitting is loosened,
retighten fitting and evacuate the system again.
A good rule for the flexible hose lines is to keep
the radius of all bends at least 10 times the diame-
ter of the hose. Sharper bends will reduce the flow
of refrigerant. The flexible hose lines should be
routed so they are at least 3 inches (80 mm) from
the exhaust manifold. Inspect all flexible hose lines
to make sure they are in good condition and prop-
erly routed.
The use of correct wrenches when making con-
nections is very important. Improper wrenches or
improper use of wrenches can damage the fittings.
The internal parts of the A/C system will remain
stable as long as moisture-free refrigerant and
refrigerant oil is used. Abnormal amounts of dirt,
moisture or air can upset the chemical stability.
This may cause operational troubles or even seri-
ous damage if present in more than very small
quantities.
When opening a refrigeration system, have every-
thing you will need to repair the system ready. This
will minimize the amount of time the system must
be opened. Cap or plug all lines and fittings as
soon as they are opened. This will help prevent the
entrance of dirt and moisture. All new lines and
components should be capped or sealed until they
are ready to be used.
All tools, including the refrigerant dispensing
manifold, the manifold gauge set, and test hoses
should be kept clean and dry.
HVAC CONTROL MODULE
The HVAC control module regulates the operation
of the various actuator motors. The actuator motors
are used to move the mode, blend- air, and recirc.
doors (Fig. 2).
The control module is included in the A/C control
head located on the instrument panel. The control
head includes the blower speed switch, rear wiper
NS/GSHEATING AND AIR CONDITIONING 24 - 3
DESCRIPTION AND OPERATION (Continued)

and washer operation, front & rear window defogger,
recirculation door operation, and A/C compressor
operation if equipped. Refer to Group 8E, Instrument
Panel and Systems for service procedures.
The rear blower speed switch is serviced separately
from the control head.
SIDE DOOR HEATER A/C OUTLETS
The driver's and passenger side doors have supple-
mental air outlets and duct work. The air is chan-
neled from the instrument panel to the door duct and
either to the lower floor or upper door outlets (Fig.
3). The air can be adjusted to blow on the first rear
passenger seat(s).
SIDE WINDOW DEMISTER
The side window demisters direct air from the
heater assembly. The outlets are located on the top
forward corners of the front door panels (Fig. 4). The
demisters operate when the control mode selector is
on FLOOR, MIX or DEFROST setting.
SYSTEM AIRFLOW
The system pulls outside (ambient) air through the
cowl opening at the base of the windshield. Then it
goes into the plenum chamber above the heaterÐA/C
unit housing. On air conditioned vehicles, the air
passes through the evaporator. At this point the air
flow can be directed either through or around the
heater core. This is done by adjusting the blend- air
door with the TEMP control on the control head. An
optional zone control HVAC control module is available.
This unit has dual blend-air doors that can be regu-
lated independently of each other. The temperature set-
ting can be different from driver's side to passenger
side. After the air passes the blend-air door(s), the air
flow can then be directed from the Panel, Floor, and
Defrost outlets. Air flow velocity can be adjusted with
the blower speed selector switch on the control head.
Ambient air intake can be shut off by closing the
recirculating air door. This will recirculate the air
that is already inside the vehicle. This is done by
depressing the Recirc. button on the control head. On
air conditioned vehicles, moving the control to Mix or
Defrost depresses the A/C button and will engage the
compressor. This will send refrigerant through the
evaporator, and remove heat and humidity from the
air before it goes through the heater core.
CAUTION: In cold weather, use of the Recirculation
mode may lead to excessive window fogging. The
Recirculation mode is automatically deactivated in
Mix and Defrost modes to improve window clearing
operation.
SYSTEM OIL LEVEL
It is important to have the correct amount of oil in
the A/C system to ensure proper lubrication of the
compressor. Too little oil will result in damage to the
compressor. Too much oil will reduce the cooling
Fig. 2 HVAC Control Module
Fig. 3 Door Outlets
Fig. 4 Demister Inlet
24 - 4 HEATING AND AIR CONDITIONINGNS/GS
DESCRIPTION AND OPERATION (Continued)