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AIR CONDITIONING/HEATER
CONTENTS
page page
A/C-HEATER SYSTEM...................... 1 HEATERSYSTEM......................... 1
GENERAL INFORMATION
This section of the wiring diagrams is divided into
two sub-sections; Heater, and A/C and Heater. When
referring to the circuit descriptions or wiring dia-
grams, ensure that you use the correct sub-section.
HEATER SYSTEM
BLOWER MOTOR
In the RUN or ACCESSORY position, the ignition
switch connects circuit A1 from fuse 6 in the Power
Distribution Center (PDC) to circuit A48. Circuit A48
supplies battery voltage to fuse 5 in the fuse block.
Fuse 5 supplies power to the heat mode switch on
circuit C7.
Circuit C43 from the heat mode switch splices to
supply voltage to the blower motor switch and the
blower motor resistor block. The blower motor switch
sets blower motor speed to HIGH, M1, M2, or LOW.
When the blower motor switch is in the LOW posi-
tion, circuit C43 from the heat mode supplies voltage
to the resistor block. Voltage does not pass through
the blower motor switch in the LOW position.In the M1 position, the blower motor switch sup-
plies voltage to the resistor block on circuit C4. From
circuit C4, voltage passes through three resistors in
the resistor block to the blower motor on circuit C1.
In the M2 position, the blower motor supplies volt-
age to the resistor block on circuit C6. From circuit
C6 voltage flows through two resistors to the blower
motor on circuit C1.
In the HIGH position, the blower motor switch con-
nects directly to the blower motor on circuit C1. Volt-
age does not pass through the resistor block.
Circuit Z1 provides ground for the blower motor.
A/C-HEATER SYSTEM
GENERAL INFORMATION
Several fuses supply power for the air conditioning/
heater system. In the START or RUN positions, the
ignition switch connects circuit A1 from fuse 6 in the
Power Distribution Center (PDC) to circuit A21. Cir-
cuit A21 powers a bus bar in the PDC that feeds cir-
cuit F12 through fuse 11. Circuit F12 feeds the
contact side of the A/C compressor clutch relay and
the coil side of the radiator fan relay (4.0L engine).
In the RUN or ACCESSORY position, the ignition
switch connects circuit A1 from fuse 11 in the PDC to
circuit A48. Circuit A48 supplies battery voltage to
fuse 5 in the fuse block. Fuse 5 supplies power to the
A/C-Heater control switch on circuit C7.
Fuse 13 in the PDC supplies battery voltage to the
contact side of the radiator fan relay on circuit F141.
Circuit A14 from fuse 15 in the PDC powers PDC
fuse 4.
BLOWER MOTOR
In the RUN or ACCESSORY position, the ignition
switch connects circuit A1 from fuse 6 in the PDC to
circuit A48. Circuit A48 supplies battery voltage to
fuse 5 in the fuse block. Fuse 5 supplies power to the
A/C-Heater control switch on circuit C7.
Circuit C43 from the A/C-heater switch splices to
supply voltage to the blower motor switch and the
blower motor resistor block. The blower motor switch
sets blower motor speed to HIGH, M1, M2, or LOW.
When the blower motor switch is in the LOW posi-
tion, circuit C43 from the A/C-Heater switch supplies
voltage to the resistor block. Voltage does not pass
through the blower motor switch in the LOW position
In the M1 position, the blower motor switch sup-
plies voltage to the resistor block on circuit C4. From
circuit C4, voltage passes through three resistors in
the resistor block to the blower motor on circuit C1.
J8W-42 AIR CONDITIONING/HEATERÐXJ VEHICLES 8W - 42 - 1
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In the M2 position, the blower motor supplies volt-
age to the resistor block on circuit C6. From circuit
C6 voltage flows through two resistors to the blower
motor on circuit C1.
In the HIGH position, the blower motor switch con-
nects directly to the blower motor on circuit C1. Volt-
age does not pass through the resistor block.
Circuit Z1 provides ground for the blower motor.
AIR CONDITIONING OPERATION
When the A/C-heater control switch is moved to an
A/C position or the defrost position, the Powertrain
Control Module (PCM) receives the A/C select signal
on circuit C90. Circuit C90 connects to cavity 28 of
the PCM.
Circuit also C90 splices to the low pressure switch
and to supply battery voltage to the coil side of the
A/C compressor clutch relay. If the low pressure
switch is closed, circuit C90 connects to circuit C21.
Circuit C21 supplies battery voltage to the A/C cy-
cling switch. Circuit C91 from the A/C cycling switch
provides the A/C request signal to the PCM. Circuit
C91 connects to cavity 27 of the PCM. Circuit Z1 pro-
vides ground for the A/C cycling switch.
After receiving the A/C request signal, the PCM
supplies ground for the A/C compressor clutch relay
on circuit C13. Circuit F12 from fuse 11 in the PDC
supplies battery voltage to the contact side of the A/C
compressor clutch relay. When the PCM grounds the
relay, the contacts close and connect circuit F12 to
circuit C3. Circuit C3 feeds the A/C compressor
clutch.
Also, after receiving the A/C request signal, the
PCM supplies ground for the coil side of the radiator
fan relay on circuit C27 (4.0L engine). Circuit C27
connects to cavity 31 of the PCM. Circuit F12 sup-
plies battery voltage to the coil side of the relay.
When the PCM grounds the coil side of the radia-
tor fan relay, the contacts close and connects circuit
F141 from fuse 4 in the PDC to circuit C25. Circuit
C25 feeds the radiator fan motor. Circuit Z1 provides
ground for the motor.
HELPFUL INFORMATION
Circuit A14 from PDC fuse 2 powers circuit F141
through fuse 15 in the PDC.
RADIATOR FAN RELAY AND MOTOR
In the START or RUN positions, the ignition
switch connects circuit A1 from fuse 6 in the Power
Distribution Center (PDC) to circuit A21. Circuit A21
powers a bus bar in the PDC that feeds circuit F12
through fuse 11. Circuit F12 feeds the coil side of the
radiator fan relay (4.0L engine).
The PCM supplies ground for the coil side of the
radiator fan relay on circuit C27 (4.0L engine). Cir-
cuit C27 connects to cavity 31 of the PCM.
When the PCM grounds the coil side of the radia-
tor fan relay, the contacts close and connects circuit
F141 from fuse 15 in the PDC to circuit C25. Circuit
C25 feeds the radiator fan motor. Circuit Z1 provides
ground for the radiator fan motor.
HELPFUL INFORMATION
Circuit A14 from PDC fuse 2 powers circuit F141
through fuse 15 in the PDC.
DIAGRAM INDEX
Component Page
A/C Compressor Clutch.....................8W-42-4
A/C Compressor Clutch Relay................8W-42-4
A/C Cycling Switch.......................8W-42-4
A/C Low Pressure Switch...................8W-42-4
A/C Mode Select Switch....................8W-42-5
Blower Motor...........................8W-42-3
Blower Motor Switch......................8W-42-3
Blower Motor Resistor.....................8W-42-3
Fuse 2 (PDC)...........................8W-42-5
Fuse 5 (Fuse Block).....................8W-42-3, 5
Fuse 6 (PDC).........................8W-42-3, 5
Fuse 11 (PDC)..........................8W-42-4
Fuse 15 (PDC)..........................8W-42-5
Heater Mode Switch.......................8W-42-3
Ignition Switch......................8W-42-3, 4, 5
Powertrain Control Module..................8W-42-4
Radiator Fan Motor.......................8W-42-5
Radiator Fan Relay.......................8W-42-5
8W - 42 - 2 8W-42 AIR CONDITIONING/HEATERÐXJ VEHICLESJ
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INTERIOR LIGHTING
INDEX
page page
Cargo Lamp, Courtesy Lamps and Dome Lamp.... 1
Chime/Buzzer Module....................... 2
Diagram Index............................ 2
General Information........................ 1
Glove Box Lamp........................... 1
Ignition Switch Lamp........................ 1Instrument Panel Illumination Lamps............ 1
Reading Lamps........................... 2
Time Delay Relay.......................... 1
Underhood Lamp.......................... 2
Visor Vanity Mirror Lamps.................... 2
GENERAL INFORMATION
Circuit M1 supplies power to the glove box lamp,
left courtesy lamp, right courtesy lamp, dome lamp,
and cargo lamp. The M1 circuit also connects to the
remote keyless entry module. Circuit M1 is protected
by the ignition off draw (IOD) fuse (fuse 9) in the fuse
block.
Circuit E2 supplies power for the instrument panel
illumination lamps.
INSTRUMENT PANEL ILLUMINATION LAMPS
Circuit E2 from the headlamp switch splices to
supply power to the following illumination lamps:
²Ash receiver lamp
²Cigar lighter lamp
²Transmission range indicator lamp
²Transfer case range indicator lamp
²A/C-Heater switch lamp
²Heated rear window lamp
²Rear wiper switch lamp
²Fog lamp switch lamp
Fuse 19 in the fuse block protects circuit E2. Circuit
Z1 provides ground for all of the illumination lamps
except for the cigar lighter lamp. The cigar lighter
lamp is case grounded.
HELPFUL INFORMATION
Circuit E2 also supplies power to the radio, LCD
relay and the illumination lamps in the instrument
cluster.
IGNITION SWITCH LAMP
The time delay relay is used to allow a time-ON
function for the ignition switch lamp and the courtesy
lamp. Power for the relay is received on the M1
circuit from the IOD fuse (fuse F9) in the fuse block.
Circuit M2 provides ground for the time delay relay
through the right and left door ajar switches and the
headlamp switch. When a door is opened, or the
headlamp switch is moved to the dome lamp position,a ground path is provided for the relay on circuit M2.
This energizes the relay, causing the contacts to close.
When the relay contacts close, power is provided
through the relay to circuit M50. The M50 circuit
supplies current to the ignition switch lamp. Circuit
Z1 provides ground for the lamp.
GLOVE BOX LAMP
Circuit M1 from the IOD fuse (fuse F9) in the fuse
block powers the glove box lamp. A case grounded
switch, in series after the lamp, closes when the glove
box door is opened. The switch completes a path to
ground on circuit Z1.
CARGO LAMP, COURTESY LAMPS AND DOME
LAMP
Circuit M1 from the IOD fuse (fuse F9) in the fuse
block supplies power to the cargo, courtesy lamps and
dome lamp. This circuit is HOT at all times. The
ground path for the lamp is provided in three differ-
ent ways.
One way is through the door jamb switches. Circuit
M2 connects to the door jamb switches from the cour-
tesy and dome lamps. The switches are connected to
ground circuit Z1. When a door is opened, the plunger
in the switch closes, completing a path to ground.
The second way is through the liftgate switch. Cir-
cuit M2 connects to circuit M4 at the cargo lamp.
Circuit M4 connects to the liftgate switch. The lift-
gate switch connects to ground circuit Z1. When the
lift gate opens, the plunger in the switch closes, com-
pleting a path to ground.
The third ground path is through the headlamp
switch. Circuit M2 is spliced in with the headlamp
switch. When the operator turns the headlamp switch
to the dome lamp ON position, a ground path is
provided through the switch.
J8W-44 INTERIOR LIGHTINGÐXJ VEHICLES 8W - 44 - 1