A/C system, the engine cooling system must be in
proper working order. The use of a bug screen is not
recommended. Any obstructions in front of the radia-
tor or A/C condenser will reduce the performance of
the A/C and engine cooling systems.

The engine cooling system includes the radiator,

thermostat, radiator hoses and the engine coolant
pump. Refer to Cooling for more information before
opening or attempting any service to the engine cool-
ing system.

HEATER AND AIR CONDITIONER SYSTEM

A manually controlled single zone type heating-air

conditioning system or a manually controlled heater-
only system is available as standard equipment on
this model (depending on market).

All vehicles are equipped with a common heater,

ventilation and air conditioning (HVAC) housing (Fig.
1). The system combines air conditioning, heating
and ventilation capabilities in a single unit mounted
within the passenger compartment under the instru-
ment panel. The HVAC housing includes:

• Blower motor

• Blower motor resistor

• Recirculation-air door and actuator (A/C system

only)

• Heater core

• A/C evaporator (A/C system only)

• Mode-air door
Based upon the system mode selected, conditioned

air can exit the standard heater-only or optional
heater-A/C unit housing through one or a combina-

tion of the three main housing outlets: defrost, panel
or floor. The defrost and panel outlets are located on
the face of the housing and the floor outlet is located
on the bottom of the housing. Once the conditioned
air exits the HVAC housing, it is further directed
through molded plastic ducts to the various outlets in
the vehicle interior. These outlets and their locations
are as follows:

• Defroster Outlet - A single large defroster out-

let is located in the center of the instrument panel
top cover, near the base of the windshield.

• Side Window Demister Outlets - There are

two side window demister outlets, one is located at
each outboard end of the instrument panel top cover,
near the belt line at the A-pillars.

• Panel Outlets - There are four panel outlets in

the instrument panel, one located near each outboard

Fig. 1 Blend-Air HVAC System-Typical

1 - BLEND-AIR DOOR
2 - A/C EVAPORATOR
3 - BLOWER MOTOR
4 - PANEL/DEFROST-AIR DOOR
5 - HEAT/DEFROST-AIR DOOR
6 - HEATER CORE
7 - RECIRCULATION-AIR DOOR

PL/SRT-4

HEATING & AIR CONDITIONING

24 - 1

end of the instrument panel facing the rear of the
vehicle and two located near the top of the instru-
ment panel center bezel.

• Front Floor Outlets - There are two front floor

outlets. One located above each side of the floor panel
center tunnel near the dash panel.

OPERATION

The heating and air conditioning system pulls out-

side (ambient) air through the cowl opening at the
base of the windshield, then into the plenum cham-
ber above the heating, ventilation and air condition-
ing (HVAC) housing. On models equipped with air
conditioning, the air passes through the evaporator.
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 instrument panel.
The air flow can then be directed from the panel,
floor and defrost outlets in various combinations
using the mode selector. Air flow velocity can be
adjusted with the blower speed selector switch on the
instrument panel.

On models equipped with air conditioning, the

ambient air intake can be controlled by opening and
closing the recirculating air door. When placed in
RECIRC, air that is inside the vehicle is continuously
recirculated through the HVAC housing. Ambient air
cannot be controlled on vehicles without A/C. The
system uses outside air at all times.

The air conditioning compressor can be engaged by

turning the fan switch counterclockwise from the Off
position. It can also be engaged by placing the mode
control in the mix to defrost positions. This will
remove heat and humidity from the air before it is
directed through or around the heater core.

The defroster outlet receives airflow from the

HVAC housing through the molded plastic defroster
duct, which is snapped onto the HVAC housing
defroster outlet and secured by a tab to a mounting
slot in the dash panel. The airflow from the defroster
outlet is directed by fixed vanes in the defroster out-
let grille and cannot be adjusted. The defroster outlet
grille is integral to the instrument panel top cover.

The side window demister outlets receive airflow

from the HVAC housing through the air outlet distri-
bution duct, two molded plastic demister hoses and
two intermediate ducts. The air outlet distribution
duct is secured to the instrument panel with screws
and receives airflow through the panel outlet of the
HVAC housing. The airflow from the side window
demister outlets is directed by fixed vanes in the
demister outlet grilles and cannot be adjusted. The
side window demister outlet grilles are integral to
the instrument panel top cover. The demisters direct
air from the HVAC housing through the outlets
located on the top corners of the instrument panel.

The demisters operate when the mode selector is
anywhere between floor and defrost settings. Some
air may be noticeable from the demister outlets when
the mode selector is in the bi-level to floor positions.

The panel outlets also receive airflow from the

HVAC housing through the air outlet distribution
duct. Molded plastic panel outlet ducts direct airflow
from the distribution duct to the outboard panel out-
lets, while a center air outlet duct directs airflow
from the distribution duct to the two center panel
outlets. The airflow from each of the panel outlets is
adjustable. A knob in the center of each panel outlet
grille is used in a joystick fashion to adjust a center
diffuser that changes the airflow direction, and a
knob on the outer edge of each panel outlet grille
opens or closes a shutter to turn airflow on or off
through that outlet.

The front floor outlets receive airflow from the

HVAC housing through the floor distribution duct.
The front floor outlets are integral to the molded
plastic floor distribution duct, which is secured to the
bottom of the HVAC housing. The floor outlets cannot
be adjusted.

DIAGNOSIS AND TESTING

A/C PERFORMANCE TEST

The A/C system is designed to remove heat and

humidity from the air entering the passenger com-
partment. The A/C evaporator, located in the HVAC
housing, is cooled to temperatures near the freezing
point. As warm damp air passes over the fins in the
evaporator, moisture in the air condenses to water,
dehumidifying the air. Condensation on the evapora-
tor fins reduces the A/C evaporators ability to absorb
heat. During periods of high heat and humidity, an
A/C system will be less effective. With the HVAC
mode control set to RECIRC, only air from the pas-
senger compartment passes through the A/C evapora-
tor. As the passenger compartment air dehumidifies,
A/C performance levels rise.

A/C PERFORMANCE TEST

WARNING: Refer to the applicable warnings and
cautions for this system before performing the fol-
lowing operation (Refer to 24 - HEATING & AIR
CONDITIONING/PLUMBING - WARNING - A/C SYS-
TEM) and (Refer to 24 - HEATING & AIR CONDI-
TIONING/PLUMBING - CAUTION - A/C SYSTEM).

Air temperature in test room and on vehicle must

be 21° C (70°F) minimum for this test.

24 - 2

HEATING & AIR CONDITIONING

PL/SRT-4

HEATING & AIR CONDITIONING (Continued)

NOTE: When connecting the service equipment
coupling to the line fitting, verify that the valve of
the coupling is fully closed. This will reduce the
amount of effort required to make the connection.

(1) Connect a tachometer and manifold gauge set.
(2) Set control to A/C, RECIRC, and PANEL, tem-

perature lever on full cool and blower on high.

(3) Start engine and hold at 1000 rpm with A/C

clutch engaged.

(4) Engine should be warmed up with doors closed

and windows open.

(5) Insert a thermometer in the left center A/C

panel outlet and operate the engine for five minutes.
The A/C clutch may cycle depending on ambient con-

ditions. If the clutch cycles, unplug the low pressure
cycling clutch switch wire harness connector from the
switch located on the accumulator. Place a jumper
wire across the terminals of the low pressure cycling
clutch switch wire harness connector.

(6) With the A/C compressor clutch engaged, com-

pare the air temperature at the center panel outlet
and the compressor discharge pressure to the A/C
Performance Temperature and Pressure chart. The
compressor clutch may cycle, depending upon the
ambient temperature and humidity. If the clutch
cycles, use the readings obtained before the clutch
disengaged.

A/C PERFORMANCE TEMPERATURE AND PRESSURE - (NON-TURBO ENGINES ONLY)

Ambient Temperature

21°C (70°F)

26.5°C (80°F)

32°C (90°F)

37°C (100°F)

43°C (110°F)

Air Temperature at Left
Center Panel Outlet

6°C (42°F)

9°C (48°F)

12°C (53°F)

14°C (57°F)

21°C (69°F)

Compressor Discharge
Pressure After the
Condenser

850 kPa (125

PSI)

1000 kPa (150

PSI

1500 kPa (215

PSI)

2000 kPa (275

PSI)

2400 kPa (350

PSI)

Evaporator Suction
Pressure

180 kPa (26

PSI)

250 kPa

(35PSI)

260 kpa (38

PSI)

310 kpa (45

PSI)

400 kPa (57

PSI)

A/C PERFORMANCE TEMPERATURE AND PRESSURE - (2.4L TURBO ENGINE ONLY)

Ambient Temperature

21°C (70°F)

26.5°C (80°F)

32°C (90°F)

37°C (100°F)

43°C (110°F)

Air Temperature at Left
Center Panel Outlet

1-8°C

(34-46°F)

3-9°C

(37-49°F)

4-10°C

(39-50°F)

6-11°C

(43-52°F)

7-18°C

(45-65°F)

Compressor Discharge
Pressure After the Filter
Drier

1034-1724 kPa

(150-250 PSI)

1517-2275 kPa

(220-330 PSI

1999-2620

kPa (290-380

PSI)

2068-2965

kPa (300-430

PSI)

2275-3421 kPa

(330-496 PSI)

Evaporator Suction
Pressure

103-207 kPa

(15-30 PSI)

117-221 kPa

(17-32 PSI)

138-241 kpa

(20-35 PSI)

172-269 kpa

(25-39 PSI)

207-345 kPa

(30-50 PSI)

(7) If the air outlet temperature fails to meet the

specifications in the A/C Performance Temperature
and Pressure chart, or if the compressor discharge
pressure is high, refer to the A/C Pressure Diagnosis
Chart.

PL/SRT-4

HEATING & AIR CONDITIONING

24 - 3

HEATING & AIR CONDITIONING (Continued)

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