1995 JEEP YJ blower motor resistor diagram

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

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

SPLICE LOCATIONS
GENERAL INFORMATION
This section provides illustrations identifying the
general location of the splices in this vehicle. A splice
index is provided. Use the wiring diagrams in each
section for splice number identification. Refer to the
index for the proper splice number.
SPLICE LOCATIONS
Splice
NumberLocations Fig.
S101 Near Generator T/O..................4
S102 Near Bulkhead T/O...................2
S103 Near Bulkhead T/O...................2
S104 Near Bulkhead T/O...................2
S105 Near Bulkhead T/O...................2
S106 Near Bulkhead T/O...................1
S107 Near Wiper Motor T/O................1
S108 Near Wiper Motor T/O................1
S109 Near Wiper Motor T/O................1
S110 Center of Dash Panel Near Grommet.......1
S111 Near T/O for ABS Diode...............7
S112 Near T/O for Map Sensor..............1
S113 Near T/O for Injector #5 and #6..........4
S114 Near T/O for Injector #5 and #6..........4
S115 Near T/O for Injector #5 and #6..........4
S116 Near T/O for Injector #5 and #6..........4
S117 Near T/O for Map Sensor..............1
S118 Near T/O for Map Sensor..............1
S119 Near Distributor T/O..................1
S120 Between Distributor T/O and Underhood
Lamp T/O.......................1
S121 Between Distributor T/O and Underhood
Lamp T/O.......................1
S122 Between Distributor T/O and Underhood
Lamp T/O.......................1
S123 RT Side of Cowl Panel................1
S124 RT Side of Cowl Panel................1
S125 Near T/O for PDC...................1
S126 Near T/O for Oil Pressure Switch..........5
S127 Near Generator T/O..................5
S128 LT Side of Grille Panel................3
S129 LT Side of Grille Panel................3
S130 Center of Grille Panel.................3
S201 Near Body Harness Connector T/O.........6
S202 Near Body Harness Connector T/O.........6
S203 Near Body Harness Connector T/O.........6
S204 Near Relay Center...................6
S205 Near T/O for Headlamp Switch...........6Splice
NumberLocations Fig.
S206 Near T/O for Telltale..................6
S207 Near T/O for Cluster..................6
S208 Near T/O for Cluster..................6
S209 Right Side of Cluster.................6
S210 Right Side of Cluster.................6
S211 Near Instrument Panel Ground T/O........6
S212 Near Wiper Switch T/O................6
S213 Near Antenna T/O...................7
S214 Near Blower Resistor T/O..............7
S215 Right Side of Instrument Panel...........7
S301 In Left Rear Door T/O.................8
S302 Near Left C-Pillar....................8
S303 Near Left C-Pillar....................8
S304 Near Left C-Pillar....................8
S305 Near Left C-Pillar....................8
S306 Near Left C-Pillar....................8
S307 Left Rear Wheel Well................10
S308 Left Rear Wheel Well................10
S309 Near Left Rear Door T/O...............8
S310 Near Left Rear Door T/O...............8
S311 Left Side of Floor Tunnel...............9
S312 Top of Floor Tunnel..................9
S313 In Power Mirror Switch T/O.............9
S314 Right A- Pillar.....................11
S315 Near RT Vanity Mirror T/O.............11
S316 Near RT Vanity Mirror T/O.............11
S317 In Trailer Tow Harness Near Grommet......14
S318 In Trailer Tow Harness Near Grommet......14
S319 In Liftgate.......................13
S320 Right A-Pillar.....................11
S321 In Left Front Door..................12
S401 In Left Rear Tail Lamp..........Not Shown
S402 In Right Rear Tail Lamp.........Not Shown
S403 In Left Rear Tail Lamp..........Not Shown
S404 In Right Rear Tail Lamp.........Not Shown
J8W-95 SPLICE LOCATIONSÐXJ VEHICLES 8W - 95 - 1

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. Whenreferring 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 PDC to
circuit A48. Circuit A48 supplies battery voltage to
fuse 4 in the fuse block. Fuse 4 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. Fromcircuit 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 in the
HIGH position.
Circuit Z1 provides ground for the blower motor.
DIAGRAM INDEX
AC/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.
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 tofuse 4 in the fuse block. Fuse 4 supplies power to the
A/C-Heater control switch on circuit C7.
Fuse 15 in the PDC supplies battery voltage to the
contact side of the radiator fan relay on circuit F141.
Circuit A14 from fuse 2 in the PDC powers PDC fuse
15.
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
J8W-42 AIR CONDITIONING/HEATERÐXJ-RHD 8W - 42 - 1

fuse 4 in the fuse block. Fuse 4 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.
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 in the
HIGH position.
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 connect circuit
F141 from fuse 15 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.
The PCM supplies ground for the coil side of the
radiator fan relay on circuit C27. Circuit C27 con-
nects to cavity 31 of the PCM.
When the PCM grounds the coil side of the radia-
tor fan relay, the contacts close and connect 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 4 (Fuse Block).....................8W-42-3, 5
Fuse 6 (PDC).......................8W-42-3, 4, 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-RHDJ

SPLICE LOCATIONS
GENERAL INFORMATION
This section provides illustrations identifying the
general location of the splices in this vehicle. A spliceindex is provided. Use the wiring diagrams in each
section for splice number identification. Refer to the
index for the proper splice number.
SPLICE LOCATIONS
Splice
NumberLocations Fig.
S101......InT/OforHorn and Radiator Fan Motor....2
S102......Before T/O for A/C Low Pressure Switch....2
S103......Before T/O for A/C Low Pressure Switch....2
S104......After T/O for A/C Low Pressure Switch.....2
S105......After T/O for A/C Low Pressure Switch.....2
S106......Before T/O for MAP Sensor............2
S107......Before T/O for MAP Sensor............2
S108......Before T/O for Injector No. 4...........4
S109......Before T/O for Injector No. 6...........4
S110......After T/O for MAP Sensor.............2
S111......After T/O for MAP Sensor.............2
S112......After T/O for Injectors................3
S113......After T/O for Injectors................3
S114......Before T/O for Brake Warning Switch......3
S115......Before T/O for Brake Warning Switch......3
S116......Before T/O for Brake Warning Switch......3
S117......InT/OforDash Connectors, Before Grommet .3
S118......InT/OforDash Connectors, Before Grommet .3
S119......InT/OforABSControl Module, After Grommet .5
S120......After T/O for Underhood Lamp..........3
S121......Before T/O for PDC..................3
S122......Before T/O for PDC..................3
S123......Before T/O for Ambient Air Temperature
Sensor........................3
S124......Near T/O for Ignition Coil and Generator....4
S125......After T/O for Left Fog Lamp............1
S126......Near Clip for Middle of Gille Opening......1
S127......Before T/O for Right Fog Lamp..........1
S201......Before T/O for Right Door Speaker (With ABS) .6
S201......Before T/O for Right Door Speaker (Without ABS)
...............................6
S202......Before T/O for Right Door Speaker (With ABS) .6
S202......Before T/O for Right Door Speaker
(Without ABS)....................6
S203......After T/O for Right Door Jamb Switch (With
ABS)...........................6
S204......Before T/O for Stop Lamp Switch (With ABS) .6
S205......Before T/O for Stop Lamp Switch (With ABS) .6
S205......Before T/O for Stop Lamp Switch (Without ABS)
...............................6
S206......Before T/O for Stop Lamp Switch (With ABS) .6
S206......After T/O for Heated Rear Window Switch and
Fog Lamp Switch (Without ABS).........6
S207......Before T/O for Headlamp Switch (With ABS) .6
S208......InT/OforHeated Rear Window Switch and Fog
Lamp Switch (With ABS)..............6Splice
NumberLocations Fig.
S208......Before T/O for Headlamp Switch
(Without ABS)....................6
S209......After T/O for Heated Rear Window Switch
and Fog Lamp Switch (With ABS).......6
S209......After T/O for Right Door Jamb Switch
(Without ABS)....................6
S210......After T/O for Heated Rear Window Switch and
Fog Lamp Switch (With ABS)...........6
S210......Before T/O for Headlamp Switch
(Without ABS)....................6
S211......After T/O for Antenna (With ABS)........6
S211......After T/O for A/C-Heater Mode Switch
(Without ABS)....................6
S212......InT/OforRelay Center (With ABS).......6
S212......InT/OforRelay Center (Without ABS).....6
S213......InT/OforRelay Center (With ABS).......6
S214......After T/O for Wiper Switch (With ABS).....6
S214......After T/O for A/C-Heater Mode Switch
(Without ABS)...................6
S215......After T/O for A/C-Heater Blower Motor
Switch (With ABS).................6
S216......After T/O for A/C-Heater Mode Switch
(With ABS)......................6
S216......After T/O for A/C-Heater Blower Motor
Switch (Without ABS)...............6
S217......After T/O for A/C-Heater Mode Switch
(With ABS)......................6
S217......After T/O for A/C-Heater Mode Switch
(Without ABS)....................6
S218......After T/O for A/C-Heater Mode Switch
(With ABS).....................6
S218......InT/OforRelay Center (Without ABS).....6
S219......After T/O for Glove Box (With ABS).......6
S220......After T/O for A/C-Heater Mode Switch
(With ABS)......................6
S220......After T/O for A/C-Heater Mode Switch
(Without ABS)....................6
S221......After T/O for Blower Motor Resistor Block
(With ABS)......................6
S222......Before T/O for Stop Lamp Switch
(Without ABS)....................6
S223......After T/O for Heated Rear Window Switch
and Fog Lamp Switch (Without ABS).....6
S224......After T/O for Glove Box (Without ABS).....6
S301......Bottom of Left Front Door Opening.......9
S302......Bottom of Left Front Door Opening.......9
S303......Bottom of Left Front Door Opening.......9
S304......Bottom of Left Front Door Opening.......9
J8W-95 SPLICE LOCATIONSÐXJ-RHD 8W - 95 - 1

AIR CONDITIONING/HEATER
CONTENTS
page page
HEATER AND AIR CONDITIONING........... 2 HEATERSYSTEM......................... 1
GENERAL INFORMATION
This section of the wiring diagrams is divided into
two sub-sections; Heater, and A/C-Heater. When re-
ferring to the circuit descriptions or wiring diagrams,
ensure that you use the correct sub-section.
HEATER SYSTEM
HEATER
In the RUN position, the ignition switch connects
circuit A1 from fuse 4 in the Power Distribution Cen-
ter (PDC) to circuit A22. Circuit A22 powers a bus
bar in the fuse block that supplies voltage to circuit
C1 through fuse 12.
A heater-off switch in circuit C1 opens when the
heater controls are in the VENT position. When the
heater-off switch closes, circuit C1 supplies battery
voltage to the blower motor switch. The switch sets
blower motor speed to HIGH, MEDIUM, LOW or
OFF.
The switch connects to the blower motor resistor
block in the LOW and MEDIUM positions and di-
rectly to the blower motor in the HIGH position. The
resistor block contains two resistors connected in se-
ries. Circuit C7 connects the resistor block to the
blower motor.
From the blower motor resistor block, circuit C7 is
double crimped at the HIGH terminal of the blower
motor switch. Circuit C7 continues to the blower mo-
tor from the blower motor switch.
When the blower motor switch is in the LOW posi-
tion, it supplies voltage to the resistor block on cir-
cuit C4. From circuit C4, voltage passes through both
resistors in the resistor block to the blower motor on
circuit C7.In the MEDIUM position, the blower motor sup-
plies voltage to the resistor block on circuit C5. From
circuit C5 voltage flows through one resistor to the
blower motor on circuit C7.
In the HIGH position, the blower motor switch con-
nects directly to the blower motor on circuit C7. Volt-
age does not pass through the resistor block.
Circuit Z1 provides ground for the blower motor.
HELPFUL INFORMATION
²Check fuse 4 in the PDC.
²Check fuse 12 in the fuse block.
DIAGRAM INDEX
Component Page
Blower Motor...........................8W-42-3
Blower Motor Resistor.....................8W-42-3
Blower Motor Switch......................8W-42-3
Fuse 4 (PDC)...........................8W-42-3
Fuse 12 (Fuse Block)......................8W-42-3
Heater Switch...........................8W-42-3
Ignition Switch..........................8W-42-3
J8W-42 AIR CONDITIONING/HEATERÐYJ VEHICLES 8W - 42 - 1

(6) Test A/C blower switch HIGH terminal with
blower switch in HIGH, should be battery voltage. If
not, replace switch.
BLOWER MOTOR
The A/C blower motor is attached to the evaporator
housing mounted under the instrument panel. The
motor has a ground wire and 3 wires connect to the
motor brushes. When voltage is applied to the sepa-
rate brushes it provides the 3 blower speeds LO,
MED, and HIGH.
BLOWER MOTOR TEST
Turn ignition switch to RUN for voltage tests and
turn ignition switch to OFF for resistance test.
(1) Test A/C blower motor ground terminal should
be 0 ohms. If not, repair ground circuit.
(2) Test A/C blower motor connector LO terminal
with blower switch in LO, should be battery voltage.
If not repair open from blower switch. If the blower
motor is still inoperative replace motor.
(3) Test A/C blower motor connector MED terminal
with blower switch in MED, should be battery volt-
age. If not repair open from blower switch. If the
blower motor is still inoperative replace motor.
(4) Test A/C blower motor connector HIGH termi-
nal with blower switch in HIGH, should be battery
voltage. If not, repair open from blower switch. If the
blower motor is still inoperative, replace motor.
HEATER DIAGNOSIS
On LHD XJ vehicles a water valve controls coolant
flow to the heater core. The valve is vacuum oper-
ated. When vacuum is applied, the valve opens and
coolant is directed through the heater core and back
to the engine. When the water valve is closed (no
vacuum applied) coolant flow bypasses the heater
core back to the engine.
The heating system receives its battery feed from
the fuse box. On YJ vehicles the feed circuit runs to
the HEATER/OFF switch and then to the BLOWER
switch. On XJ vehicles the feed circuit runs to the
HEAT/MODE switch and then to the BLOWER
switch.
The blower speed is controlled by the blower switch
and blower resistors. With the switch in LO, battery
voltage is supplied to the motor through all of the re-
sistors. The motor runs slowly. When the blower
switch is moved to a higher speed, battery voltage in-
creases to the blower motor which increase its speed.
This is accomplished by bypassing some of the blower
resistors. When the switch is in HI, blower resistors
are bypassed and battery voltage is applied directly
to the blower motor.
The following chart has been developed for quick
reference.
Refer to the Group 8W Wiring Diagrams for com-
plete wiring schematic.
JHEATING AND AIR CONDITIONING 24 - 17