AC(diag)-22
Diagnostics for A/C System Malfunction
HVAC SYSTEM (AUTO A/C) (DIAGNOSTICS)
7CHECK A/C ON SIGNAL.
1) Turn the ignition switch to OFF.
2) Connect the A/C relay and all disconnected
connectors.
3) Start the engine and turn the AUTO switch
to ON.
4) Turn the temperature control dial at maxi-
mum cool position.
5) Measure the voltage between auto A/C
control module harness connector terminal
and chassis ground.
Connector & terminal
(B283) No. 6 (+) — Chassis ground (–):
Is the voltage more than 10 V? Go to step 9.Go to step 8.
8CHECK HARNESS BETWEEN AUTO A/C
CONTROL MODULE AND ECM.
1) Turn the ignition switch to OFF.
2) Disconnect the harness connector of auto
A/C control module and ECM.
3) Measure the resistance of harness
between auto A/C control module connector
and ECM connector.
Connector & terminal
(B283) No. 6 — (B136) No. 24:
Is the resistance less than 1
Ω?
Replace the auto
A/C control mod-
ule.
Control Unit (Auto
A/C Model).>
Repair the har-
ness.
9CHECK MAGNET CLUTCH ON SIGNAL.
1) Stop the engine, and turn the AUTO switch
to OFF.
2) Turn the ignition switch to ON.
3) Measure the voltage between ECM con-
nector terminal and chassis ground.
Connector & terminal
(B136) No. 9 (+) — Chassis ground (–):
Is the voltage more than 10 V? Go to step 10.Check for open or
short circuit in the
harness between
A/C relay and
ECM.
10 CHECK MAGNET CLUTCH ON SIGNAL.
1) Start the engine and turn the AUTO switch
to ON.
2) Turn the temperature control dial at maxi-
mum cool position.
3) Measure the voltage between ECM con-
nector terminal and chassis ground.
Connector & terminal
(B136) No. 9 (+) — Chassis ground (–):
Is the voltage 0 V? Go to step 11.Replace the ECM.
REMOVAL,
Engine Control
Module (ECM).>
11 CHECK POWER SUPPLY FOR MAGNET
CLUTCH.
1) Stop the engine, and turn the AUTO switch
to OFF.
2) Disconnect the harness connector of mag-
net clutch.
3) Start the engine and turn the AUTO switch
to ON.
4) Turn the temperature control dial at maxi-
mum cool position.
5) Measure the voltage between magnet
clutch harness connector terminal and chassis
ground.
Connector & terminal
(F24) No. 1 (+) — Chassis ground (–):
Is the voltage more than 10 V? Go to step 12.Check for open or
short circuit in the
harness between
A/C relay and
magnet clutch.
Step Check Yes No
AC(diag)-23
Diagnostics for A/C System Malfunction
HVAC SYSTEM (AUTO A/C) (DIAGNOSTICS)
12 CHECK THE MAGNET CLUTCH
1) Stop the engine, and turn the AUTO switch
to OFF.
2) Disconnect the harness connector of mag-
net clutch.
Connector & terminal
(F24) No. 2 — Chassis ground:
3) Connect the battery positive (+) terminal to
terminal No. 1 of the magnet clutch, and nega-
tive (–) terminal to the compressor body.
Is the magnetic clutch operat-
ing?
Magnetic clutch is
normal.
Replace the com-
pressor.
Compressor.>
Step Check Yes No
AC(diag)-25
Diagnostic Procedure for Actuators
HVAC SYSTEM (AUTO A/C) (DIAGNOSTICS)
Step Check Yes No
1CHECK POWER SUPPLY FOR INTAKE
DOOR ACTUATOR.
1) Turn the ignition switch to OFF.
2) Disconnect the intake door actuator con-
nector.
3) Turn the ignition switch to ON.
4) Measure the voltage between intake door
actuator connector and chassis ground.
Connector & terminal
(B91) No. 7 (+) — Chassis ground (–):
Is the voltage 8 V (at normal
temperature)?
Go to step 2.Check for open or
short circuit in the
harness between
intake door actua-
tor and fuse.
2CHECK HARNESS BETWEEN AUTO A/C
CONTROL MODULE AND INTAKE DOOR
ACTUATOR.
1) Turn the ignition switch to OFF.
2) Disconnect the auto A/C control module
connector.
3) Measure the resistance between intake
door actuator connector and auto A/C control
module connector.
Connector & terminal
(B283) No. 10 — (B91) No. 1:
(B283) No. 23 — (B91) No. 3:
Is the resistance less than 1
Ω?
Go to step 3.Repair the har-
ness between auto
A/C control mod-
ule and intake
door actuator.
3CHECK OPERATION OF INTAKE DOOR AC-
TUATOR.
1) Connect the intake door actuator connec-
tor.
2) Ground the auto A/C control module con-
nector with a suitable wire.
3) Turn the ignition switch to ON, and check
the operation of intake door actuator.
Connector & terminal
(B283) No. 10 — Chassis ground:
Does the actuator move to the
FRESH side?
Go to step 4.Replace the intake
door actuator.
tor.>
4CHECK OPERATION OF INTAKE DOOR AC-
TUATOR.
1) Turn the ignition switch to OFF.
2) Ground the auto A/C control module con-
nector with a suitable wire.
3) Turn the ignition switch to ON, and check
the operation of intake door actuator.
Connector & terminal:
(B283) No. 23 — Chassis ground:
Does the actuator move to the
RECIRC side?
Replace the auto
A/C control mod-
ule.
Control Unit (Auto
A/C Model).>
Replace the intake
door actuator.
tor.>
AC(diag)-27
Diagnostic Procedure for Actuators
HVAC SYSTEM (AUTO A/C) (DIAGNOSTICS)
Step Check Yes No
1CHECK POWER SUPPLY FOR MODE DOOR
ACTUATOR POSITION SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the mode door actuator con-
nector.
3) Turn the ignition switch and AUTO switch to
ON.
4) Measure the voltage between auto A/C
control module connector terminals.
Connector & terminal
(B282) No. 8 (+) — (B282) No. 15 (–):
Is the voltage approx. 5 V? Go to step 2.Replace the auto
A/C control mod-
ule.
Control Unit (Auto
A/C Model).>
2CHECK POWER SUPPLY FOR MODE DOOR
ACTUATOR.
Measure the voltage between auto A/C control
module connector and chassis ground after
turning the air flow control switch to FACE posi-
tion.
Connector & terminal
(B283) No. 7 (+) — Chassis ground (–):
Is the voltage 8 V (at normal
temperature)?
Go to step 3.Replace the auto
A/C control mod-
ule.
Control Unit (Auto
A/C Model).>
3CHECK POWER SUPPLY FOR MODE DOOR
ACTUATOR.
Measure the voltage between auto A/C control
module connector and chassis ground after
turning the air flow control switch to DEF posi-
tion.
Connector & terminal
(B283) No. 20 (+) — Chassis ground (–):
Is the voltage 8 V (at normal
temperature)?
Go to step 4.Replace the auto
A/C control mod-
ule.
4CHECK HARNESS BETWEEN AUTO A/C
CONTROL MODULE AND MODE DOOR AC-
TUATOR.
1) Turn the A/C and ignition switch to OFF.
2) Disconnect the auto A/C control module
connector.
3) Measure the resistance between auto A/C
control module and mode door actuator con-
nector.
Connector & terminal
(B77) No. 1 — (B282) No. 15:
(B77) No. 3 — (B282) No. 8:
(B77) No. 5 — (B282) No. 3:
(B77) No. 6 — (B283) No. 20:
(B77) No. 7 — (B283) No. 7:
Is the resistance less than 1
Ω?
Go to step 5.Repair the har-
ness between auto
A/C control mod-
ule and mode door
actuator.
5CHECK MODE DOOR ACTUATOR POSI-
TION SWITCH SIGNAL.
1) Connect the connector of auto A/C control
module and mode door actuator.
2) Turn the ignition switch and AUTO switch to
ON.
3) Check the voltage between auto A/C con-
trol module connector terminals while chang-
ing the mode between DEF and FACE.
Connector & terminal
(B282) No. 3 (+) — (B282) No. 15 (–):
Does the voltage change
between 1 V (DEF) and 4 V
(FACE)?
Go to step 6.Replace the mode
door actuator.
tor.>
6CHECK POOR CONTACT.
Check poor contact of auto A/C control module
and connector.
Is there poor contact in con-
nector?
Repair the con-
nector.
Replace the auto
A/C control mod-
ule.
Control Unit (Auto
A/C Model).>
AC(diag)-29
Diagnostic Procedure for Actuators
HVAC SYSTEM (AUTO A/C) (DIAGNOSTICS)
Step Check Yes No
1CHECK POWER SUPPLY FOR AIR MIX
DOOR ACTUATOR POSITION SWITCH.
1) Turn the ignition switch to OFF.
2) Disconnect the air mix door actuator con-
nector.
3) Turn the ignition switch and AUTO switch to
ON.
4) Measure the voltage between auto A/C
control module connector terminals.
Connector & terminal
(B282) No. 8 (+) — (B282) No. 15 (–):
Is the voltage approx. 5 V? Go to step 2.Replace the auto
A/C control mod-
ule.
Control Unit (Auto
A/C Model).>
2CHECK POWER SUPPLY FOR AIR MIX
DOOR ACTUATOR.
Measure the voltage between auto A/C control
module connector and chassis ground after
turning the temperature control dial to maxi-
mum COOL position.
Connector & terminal
Driver’s side
(B283) No. 22 (+) — Chassis ground (–):
Passenger’s side
(B283) No. 21 (+) — Chassis ground (–):
Is the voltage 8 V (at normal
temperature)?
Go to step 3.Replace the auto
A/C control mod-
ule.
Control Unit (Auto
A/C Model).>
3CHECK POWER SUPPLY FOR AIR MIX
DOOR ACTUATOR.
Measure the voltage between auto A/C control
module connector and chassis ground after
turning the temperature control dial to maxi-
mum HOT position.
Connector & terminal
Driver’s side
(B283) No. 9 (+) — Chassis ground (–):
Passenger’s side
(B283) No. 4 (+) — Chassis ground (–):
Is the voltage 8 V (at normal
temperature)?
Go to step 4.Replace the auto
A/C control mod-
ule.
Control Unit (Auto
A/C Model).>
4CHECK HARNESS BETWEEN AUTO A/C
CONTROL MODULE AND AIR MIX DOOR
ACTUATOR.
1) Turn the A/C and ignition switch to OFF.
2) Disconnect the auto A/C control module
connector.
3) Measure the resistance between auto A/C
control module and air mix door actuator con-
nector.
Connector & terminal
Driver’s side
(B390) No. 1 — (B282) No. 15:
(B390) No. 3 — (B282) No. 8:
(B390) No. 5 — (B282) No. 12:
(B390) No. 6 — (B283) No. 9:
(B390) No. 7 — (B283) No. 22:
Passenger’s side
(B235) No. 1 — (B282) No. 8:
(B235) No. 3 — (B282) No. 15:
(B235) No. 5 — (B282) No. 4:
(B235) No. 7 — (B283) No. 8:
(B235) No. 6 — (B283) No. 21:
Is the resistance less than 1
Ω?
Go to step 5.Repair the har-
ness between auto
A/C control mod-
ule and air mix
door actuator.
AC(diag)-30
Diagnostic Procedure for Actuators
HVAC SYSTEM (AUTO A/C) (DIAGNOSTICS)
5CHECK AIR MIX DOOR ACTUATOR POSI-
TION SWITCH SIGNAL.
1) Connect the connector of auto A/C control
module and air mix door actuator.
2) Turn the ignition switch and AUTO switch to
ON.
3) Check the voltage between auto A/C con-
trol module connector terminals while chang-
ing the setting temperature between maximum
COOL and maximum HOT.
Connector & terminal
Driver’s side
(B282) No. 12 (+) — (B282) No. 15 (–):
Passenger’s side
(B282) No. 4 (+) — (B282) No. 15 (–):
Does the voltage change
between 1 V (Max. HOT) and 4
V (Max. COOL)?
Go to step 6.Replace the air
mix door actuator.
tor.>
6CHECK POOR CONTACT.
Check poor contact of auto A/C control module
and connector.
Is there poor contact in con-
nector?
Repair the con-
nector.
Replace the auto
A/C control mod-
ule.
Control Unit (Auto
A/C Model).>
Step Check Yes No
AC(diag)-31
Diagnostic Procedure for Sensors
HVAC SYSTEM (AUTO A/C) (DIAGNOSTICS)
8. Diagnostic Procedure for Sensors
A: AMBIENT SENSOR
TROUBLE SYMPTOM:
Fan speed is not switched when the fan speed control dial is in AUTO position.
WIRING DIAGRAM:
AC-01341
B283
F78
B1B14
B:
21
F78
12
1011
1413
B26B25
C3C10
F108
B361
B280
B281
B:
C:
5467821931022 23111213141524 25 26 2716171828 29192021 30
B280B:B281
567821943102422 2325111213141526 27281617181920 21
C:
1234567891011121314
B361
123 8910411 12 13 14 15 165671718
F108
AUTO A/CCONTROL MODULE
AMBIENT SENSOR
BODY INTEGRATED UNIT
THROUGH JOINT CONNECTOR
B283B:
1234567891014151617181920212223111213242526
AC(diag)-32
Diagnostic Procedure for Sensors
HVAC SYSTEM (AUTO A/C) (DIAGNOSTICS)
Step Check Yes No
1CHECK AMBIENT SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ambient
sensor.
3) Measure the resistance between connector
terminals of ambient sensor.
Te r m i n a l s
No. 1 — No. 2:
Is the resistance approximately
1.7 kΩ at 25°C (77°F)?
Go to step 2.Replace the ambi-
ent sensor.
2CHECK INPUT SIGNAL FOR AMBIENT SEN-
SOR.
1) Turn the ignition to ON.
2) Measure the voltage between connector
(F78) terminals.
Connector & terminal
(F78) No. 1 (+) — No. 2 (–):
Is the voltage approx. 5 V? Go to step 6.Go to step 3.
3CHECK OUTPUT SIGNAL OF BODY INTE-
GRATED UNIT.
1) Turn the ignition switch to OFF.
2) Draw out the body integrated unit.
3) Disconnect the connector from ambient
sensor.
4) Turn the ignition switch to ON.
5) Measure the voltage between connector
terminals of body integrated unit.
Connector & terminal
(B281) No. 3 (+) — No. 10 (–):
Is the voltage approx. 5 V? Go to step 4.Go to step 6.
4CHECK HARNESS CONNECTOR BETWEEN
BODY INTEGRATED UNIT AND AMBIENT
SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from body inte-
grated unit.
3) Measure the resistance of harness
between body integrated unit and ambient sen-
sor.
Connector & terminal
(F78) No. 1 — (B281) No. 10:
Is the resistance less than 1
Ω?
Go to step 5.Repair the open
circuit of harness
between body inte-
grated unit and
ambient sensor.
5CHECK HARNESS CONNECTOR BETWEEN
BODY INTEGRATED UNIT AND AMBIENT
SENSOR.
Measure the resistance of harness between
body integrated unit and ambient sensor.
Connector & terminal
(F78) No. 2 — (B281) No. 3:
Is the resistance less than 1
Ω?
Go to step 6.Repair the open
circuit of harness
between body inte-
grated unit and
ambient sensor.
6CHECK COMMUNICATION ERROR DIS-
PLAY.
1) Connect the connectors of body integrated
unit and ambient sensor as originally con-
nected.
2) Check if “Er xx” is displayed on the Odo/Trip
meter in combination meter after turning the
ignition switch to ON.
Is “Er xx” displayed? Check the commu-
nication circuit.
Diagnostic Proce-
dure.>
Go to step 7.
7CHECK POOR CONTACT.
Check poor contact of auto A/C control module
connector.
Is there poor contact in con-
nector?
Repair the con-
nector.
Replace the auto
A/C control mod-
ule.
Control Unit (Auto
A/C Model).>