Chrysler PT Cruiser. Manual - part 974

(6) Disconnect the control cables from the mode

and temperature control levers at the rear of the
A/C-heater control.

(7) Remove the A/C-heater control from the vehi-

cle.

INSTALLATION

NOTE: Make sure to properly connect the vacuum
harness to the A/C-heater control. Failure to prop-
erly connect the vacuum harness will cause the
heating-A/C system to remain in the Recirculation
mode, which will result in higher blower motor
noise levels and possible condensation on the
inside of the windows.

(1) Properly connect the vacuum harness, control

cables and wire harness to the back of the A/C-heater
control.

(2) Adjust the mode and temperature control

cables. Refer to the following Cable Adjustment Pro-
cedure.

(3) Install the A/C-heater control to the instrument

panel. Tighten the screws to 2 N·m (17 in. lbs.).

(4) Install the center air duct (Refer to 24 - HEAT-

ING & AIR CONDITIONING/DISTRIBUTION/AIR
OUTLETS - INSTALLATION).

(5) Install the instrument panel center bezel (Refer

to 23 - BODY/INSTRUMENT PANEL/INSTRUMENT
PANEL CENTER BEZEL - INSTALLATION).

CABLE ADJUSTMENT PROCEDURE

(1) With the A/C-heater control removed from the

instrument panel and the control cable retaining
clips removed, turn the mode and the temperature
controls completely counterclockwise.

(2) While holding the mode and the temperature

controls in the counterclockwise position, pull on the
gray casing of the control cables until all free play in
the cables is removed and the air doors are indexed
to the controls.

(3) Install the cable retaining clips. Make sure

that the control cables are securely positioned by the
retaining clips.

A/C HIGH PRESSURE SWITCH

DESCRIPTION

The A/C high pressure switch controls both A/C

compressor clutch engagement/disengagement, and
electric cooling fan operation. The A/C high pressure
switch is mounted at the rear of the A/C compressor.
The A/C high pressure switch turns off the A/C com-
pressor if the refrigerant system pressure exceeds
3100 - 3375 kPa (450 - 490 psi).

OPERATION

The contacts in the A/C high pressure switch open

and close causing the powertrain control module
(PCM) or the engine control module (ECM) (depend-
ing on application) to turn the A/C compressor clutch
on and off. This prevents A/C compressor operation
when the discharge pressure approaches high levels,
and also reduces electrical surging from A/C clutch
engagement.

The A/C high pressure switch controls the electric

cooling fan operation by monitoring refrigerant line
pressures. When the discharge pressure rises above
1900 to 2200 kPa (280 to 320 psi) the fan will turn
on. The cooling fan will turn off when the discharge
pressure drops to 1600 kPa (235 psi).

The A/C high pressure switch contacts open when

the discharge pressure rises above 3100 to 3375 kPa
(450 to 490 psi). The A/C high pressure switch con-
tacts close when the discharge pressure drops to
1860 to 2275 kPa (270 to 330 psi).

The A/C high pressure switch is factory-calibrated

and cannot be adjusted or repaired. If the A/C high
pressure switch is faulty or damaged, it must be
replaced.

Fig. 12 Vacuum Harness, Control Cables and Wiring

Harness

1 - A/C-HEATER CONTROL
2 - WIRE HARNESS CONNECTOR
3 - MODE CONTROL LEVER
4 - CABLE RETAINING CLIP
5 - MODE CONTROL CABLE
6 - TEMPERATURE CONTROL LEVER
7 - CABLE RETAINING CLIP
8 - TEMPERATURE CONTROL CABLE
9 - VACUUM HARNESS CONNECTOR

24 - 18

CONTROLS

A/C HEATER CONTROL (Continued)

DIAGNOSIS AND TESTING

A/C HIGH PRESSURE SWITCH

Before performing diagnosis of the A/C high pres-

sure switch, verify that the refrigerant system has
the correct refrigerant charge (Refer to 24 - HEAT-
ING & AIR CONDITIONING/PLUMBING - STAN-
DARD PROCEDURE - REFRIGERANT SYSTEM
CHARGE)

For circuit descriptions and diagrams, refer to the

appropriate wiring information. The wiring informa-
tion includes wiring diagrams, proper wire and con-
nector repair procedures, further details on wire
harness routing and retention, as well as pin-out and
location views for the various wire harness connec-
tors, splices and grounds.

(1) Disconnect and isolate the negative battery

cable.

(2) Disconnect the wire harness connector from the

A/C high pressure switch.

(3) Check for continuity between both terminals of

the A/C high pressure switch. There should be conti-
nuity. If there is not continuity, replace the faulty
A/C high pressure switch. If there is continuity, test
the A/C high pressure switch sense circuit (Refer to 8
- ELECTRICAL/WIRING DIAGRAM INFORMATION
- DIAGNOSIS AND TESTING). Repair as required.

REMOVAL

WARNING: Review safety precautions and warnings
in this group before performing this procedure
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - WARNINGS) and (Refer to 24 - HEAT-
ING & AIR CONDITIONING/PLUMBING - CAUTIONS).
Failure to follow the warnings and cautions could
result in possible personal injury or death.

(1) Disconnect and isolate the negative battery

cable.

(2) Recover refrigerant from A/C system (Refer to

24 - HEATING & AIR CONDITIONING - STAN-
DARD PROCEDURE - REFRIGERANT SYSTEM
RECOVERY).

(3) Raise and support the vehicle.
(4) Disconnect the wire harness connector from the

A/C high pressure switch located at the rear of the
A/C compressor (Fig. 13).

(5) Using snap ring pliers, remove the internal

snap ring that secures the A/C high pressure switch
to the A/C compressor.

(6) Pull the A/C high pressure switch out of the

A/C compressor and remove and discard the O-ring
seal.

INSTALLATION

(1) Clean any foreign matter from the switch

mounting bore.

(2) Remove the tape or plug from the switch port

at the rear of the A/C compressor.

(3) Lubricate a new rubber O-ring seal with clean

refrigerant oil and install it onto A/C high pressure
switch. Use only the specified O-ring as it is made of
a special material for the R-134a system. Use only
refrigerant oil of the type recommended for the A/C
compressor in the vehicle.

(4) Install the A/C high pressure switch onto the

rear of the A/C compressor.

(5) Using snap ring pliers, install the internal

snap ring that secures the A/C high pressure switch
to the A/C compressor.

(6) Connect the wire harness connector to the A/C

high pressure switch.

(7) Lower the vehicle.
(8) Reconnect the negative battery cable.
(9) Evacuate the refrigerant system (Refer to 24 -

HEATING & AIR CONDITIONING - STANDARD
PROCEDURE - REFRIGERANT SYSTEM EVACU-
ATE).

(10) Charge the refrigerant system (Refer to 24 -

HEATING & AIR CONDITIONING - STANDARD
PROCEDURE

REFRIGERANT

SYSTEM

CHARGE).

Fig. 13 A/C High Pressure Switch - Typical

1 - A/C DISCHARGE LINE
2 - A/C COMPRESSOR
3 - A/C HIGH PRESSURE SWITCH
4 - A/C SUCTION LINE

CONTROLS

24 - 19

A/C HIGH PRESSURE SWITCH (Continued)

A/C LOW PRESSURE SWITCH

DESCRIPTION

The A/C low pressure switch is a single pole, single

throw, pressure actuated switch that is used to con-
trol evaporator freeze up.

The A/C low pressure switch is mounted on a fit-

ting located on the top of the A/C accumulator. The
A/C low pressure switch fitting on the accumulator is
equipped with an O-ring and contains a Schrader-
type valve, which allows the switch to be serviced
without discharging the refrigerant system.

OPERATION

The A/C low pressure switch is electrically con-

nected in series with the A/C-heater control and the
A/C high pressure switch, between ground and the
powertrain control module (PCM) or the engine con-
trol module (ECM), depending on engine application.

The A/C low pressure switch contact opens or

closes the path the ground, signaling the PCM or
ECM to turn the A/C compressor clutch on and off.
This regulates the refrigerant system pressure and
controls evaporator coil temperature. Controlling the
evaporator temperature prevents condensate water
on the evaporator fins from freezing and obstructing
air conditioning system air flow.

The A/C low pressure switch contacts are open

when the A/C suction line pressure is approximately
152 kPa (22 psi) or lower. The A/C low pressure
switch contacts will close when the A/C suction line
pressure rises to approximately 234 to 262 kPa (34 to
38 psi) or above. Lower ambient temperatures, below
approximately -1° C (30° F), will also cause the A/C
low pressure switch contacts to open. This is due to
the pressure/temperature relationship of the refriger-
ant in the system.

The A/C low pressure switch is factory-calibrated

and cannot be adjusted or repaired. If the A/C low
pressure switch is faulty or damaged, it must be
replaced.

DIAGNOSIS AND TESTING

A/C LOW PRESSURE SWITCH

NOTE: Lower ambient temperatures, below about
-1° C (30° F), during cold weather will open the A/C
low pressure switch contacts and prevent A/C com-
pressor operation due to the pressure/temperature
relationship of the refrigerant.

Before performing diagnosis of the A/C low pres-

sure switch, verify that the refrigerant system has
the correct refrigerant charge (Refer to 24 - HEAT-

ING & AIR CONDITIONING/PLUMBING - STAN-
DARD PROCEDURE - REFRIGERANT SYSTEM
CHARGE) and that the A/C low pressure switch is
properly installed on the accumulator fitting. If the
A/C low pressure switch is not properly installed, it
may not open the Schrader-type valve in the accumu-
lator fitting, which will prevent the switch from cor-
rectly monitoring the refrigerant system pressure.

For circuit descriptions and diagrams, refer to the

(1) With gear selector in Park or Neutral and with

park brake set, start the engine and allow it to idle.

(2) Place the A/C-heater mode control in any A/C

position.

(3) Disconnect the wire harness connector from the

A/C low pressure switch.

(4) Using a suitable jumper wire, install the

jumper wire between the two terminals of the wire
harness connector for the A/C low pressure switch.
The A/C compressor clutch should engage. If the A/C
clutch does engage, replace the faulty A/C low pres-
sure switch. If the A/C clutch does not engage, the
A/C clutch, A/C clutch relay, A/C-heater control, A/C
high pressure switch, PCM or ECM (depending on
engine application), fuses or related wiring circuits
may be defective (Refer to 8 - ELECTRICAL/WIRING
DIAGRAM

INFORMATION

DIAGNOSIS AND

TESTING). Repair as required.

REMOVAL

NOTE: Note: It is not necessary to discharge the
refrigerant system to replace the A/C low pressure
switch.

(1) Disconnect and isolate the battery negative

cable.

(2) Disconnect the wire harness connector from the

A/C low pressure switch (Fig. 14).

(3) Remove the A/C low pressure switch from the

accumulator and remove and discard the O-ring seal.

INSTALLATION

NOTE: Replace the O-ring seal before installing the
A/C low pressure switch.

(1) Lubricate a new O-ring seal with clean refrig-

erant oil and install it onto the accumulator fitting.
Use only the specified O-rings as they are made of a
special material for the R-134a system. Use only

24 - 20

CONTROLS

refrigerant oil of the type recommended for the A/C
compressor in the vehicle.

(2) Install the A/C low pressure switch onto the

accumulator. Hand-tightened the switch securely.

(3) Connect the wiring harness connector to the

A/C low pressure switch.

(4) Reconnect the battery negative cable.

BLOWER MOTOR RESISTOR

DESCRIPTION

The blower motor resistor (Fig. 15) is located in the

cowl, at the base of the windshield. There are two
different

blower

motor

resistors

depending

whether the vehicle is equipped with A/C or not.

The blower motor resistor is mounted to the dash

panel within the engine compartment. The resistor
consists of a molded plastic mounting plate with an
integral wire connector receptacle. Concealed behind
the mounting plate are coiled resistor wires con-
tained within a protective stamped steel cage. The
blower motor resistor is accessed for service by
removing the cowl top screen.

OPERATION

The blower motor resistor is connected to the vehi-

cle electrical system through a dedicated take out
and connector of the vehicle harness. The blower
motor resistor has multiple resistor wires, each of

which will reduce the current flow through the
blower motor to change the blower motor speed. The
blower motor switch directs the ground path for the
blower motor through the correct resistor wire to
obtain the selected speed.

With the blower motor switch in the lowest speed

position, the ground path for the motor is applied
through all of the resistor wires. Each higher speed
selected with the blower motor switch applies the
blower motor ground path through fewer of the resis-
tor wires, increasing the blower motor speed. When
the switch is in the highest speed position, blower
motor resistor is bypassed and the blower motor
receives a direct path to ground.

The blower motor resistor cannot be adjusted or

repaired and, if faulty or damaged, it must be
replaced.

DIAGNOSIS AND TESTING

BLOWER MOTOR RESISTOR

WARNING: On vehicles equipped with airbags, dis-
able the airbag system before attempting any steer-
ing wheel, steering column, or instrument panel
component diagnosis or service. Disconnect and
isolate the negative battery (ground) cable, then
wait two minutes for the airbag system capacitor to
discharge before performing further diagnosis or
service. This is the only sure way to disable the air-
bag system. Failure to take the proper precautions
could result in accidental airbag deployment and
possible personal injury or death.

Fig. 14 A/C Low Pressure Switch - Typical

1 - ACCUMULATOR
2 - A/C LOW PRESSURE SWITCH
3 - WIRE HARNESS CONNECTOR

Fig. 15 Blower Motor Resistor

1 - BLOWER MOTOR RESISTOR
2 - RESISTORS

CONTROLS

24 - 21

A/C LOW PRESSURE SWITCH (Continued)

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