Air INFINITI QX56 2004 Factory Service Manual

ATC-72
TROUBLE DIAGNOSIS
Revision: August 20072004 QX56
3. CHECK PBR REFERENCE SIGNAL VOLTAGE
1. Turn ignition switch OFF.
2. Disconnect air mix door motor (Passenger) connector M143.
3. Turn ignition switch ON.
4. Check voltage between air mix door motor (Passenger) harness
connector M143 terminal 3 (Y) and ground.
OK or NG
OK >> GO TO 5.
NG >> GO TO 4.
4. CHECK PBR REFERENCE VOLTAGE CIRCUIT BETWEEN AIR MIX DOOR (PASSENGER) AND
FRONT AIR CONTROL
1. Turn ignition switch OFF.
2. Disconnect front air control connector M49.
3. Check continuity between air mix door motor (Passenger) har-
ness connector M143 terminal 3 (Y) and front air control harness
connector M49 terminal 2 (Y).
OK or NG
OK >> Replace front air control. Refer to ATC-135, "FRONT
AIR CONTROL" .
NG >> Repair or replace harness as necessary.
5. CHECK PBR GROUND REFERENCE CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect front air control connector M49.
3. Check continuity between air mix door motor (Passenger) har-
ness connector M143 terminal 2 (P) and front air control harness
connector M49 terminal 15 (P).
OK or NG
OK >> GO TO 6.
NG >> Repair or replace harness as necessary.
6. CHECK PBR FEEDBACK SIGNAL
1. Reconnect front air control connector and air mix door motor
(Passenger) connector.
2. Turn ignition switch ON.
3. Check voltage between front air control harness connector M50
terminal 41 (R/W) and ground.
4. Rotate temperature dial (Passenger) through complete range.
OK or NG
OK >> Replace front air control. Refer to ATC-135, "FRONT
AIR CONTROL" .
NG >> GO TO 7. 3 - Ground : Approx.5V
LJIA0044E
3 - 2 Continuity should exist.
LJIA0045E
2 - 15 Continuity should exist.
WJIA0549E
41 - Ground : Approx. 0 - 5V
LJIA0047E

TROUBLE DIAGNOSIS
ATC-73
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Revision: August 20072004 QX56
7. CHECK PBR FEEDBACK CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect air mix door motor (Passenger) connector M143 and
front air control connector M50.
3. Check continuity between air mix door motor (Passenger) har-
ness connector M143 terminal 4 (R/W) and front air control har-
ness connector M50 terminal 41 (R/W).
OK or NG
OK >> Replace air mix door motor (Passenger). Refer to AT C -
154, "FRONT AIR MIX DOOR MOTOR (PASSENGER)"
.
NG >> Repair or replace harness as necessary.
DIAGNOSTIC PROCEDURE FOR AIR MIX DOOR MOTOR (REAR)
1. CHECK RESULT FROM FRONT AIR CONTROL SELF-DIAGNOSIS
Self-diagnosis code 38 is present. Refer to ATC-53, "
A/C System Self-diagnosis Function" .
YES or NO
YES >> GO TO 2.
NO >> GO TO 3.
2. CHECK POWER SUPPLY CIRCUIT FOR AIR MIX DOOR MOTOR (REAR)
1. Turn ignition switch OFF.
2. Disconnect front air control connector M50 and air mix door
motor (Rear) connector B155.
3. Check continuity between front air control harness connector
M50 terminal 27 (GR/R) and air mix door motor (Rear) harness
connector B155 terminal 1 (GR/R) and between front air control
harness connector M50 terminal 28 (L/Y) and air mix door motor
(Rear) harness connector B155 terminal 6 (L/Y).
OK or NG
OK >> Replace air mix door motor (Rear). Refer to ATC-154, "REAR AIR MIX DOOR MOTOR" .
NG >> Repair or replace harness as necessary.
3. CHECK PBR REFERENCE SIGNAL VOLTAGE
1. Turn ignition switch OFF.
2. Disconnect air mix door motor (Rear) connector B155.
3. Turn ignition switch ON.
4. Check voltage between air mix door motor (Rear) harness con-
nector B155 terminal 3 (Y) and ground.
OK or NG
OK >> GO TO 5.
NG >> GO TO 4.4 - 41 : Continuity should exist.
WJIA0550E
27 - 1 Continuity should exist.
28 - 6 Continuity should exist.
LJIA0049E
3 - Ground : Approx. 5V
LJIA0050E

ATC-74
TROUBLE DIAGNOSIS
Revision: August 20072004 QX56
4. CHECK PBR REFERENCE VOLTAGE CIRCUIT BETWEEN AIR MIX DOOR MOTOR (REAR) AND
FRONT AIR CONTROL
1. Turn ignition switch OFF.
2. Disconnect front air control connector M49.
3. Check continuity between air mix door motor (Rear) harness
connector B155 terminal 3 (Y) and front air control harness con-
nector M49 terminal 2 (Y).
OK or NG
OK >> Replace front air control. Refer to ATC-135, "FRONT
AIR CONTROL" .
NG >> Repair or replace harness as necessary.
5. CHECK PBR GROUND REFERENCE CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect front air control connector M49.
3. Check continuity between air mix door motor (Rear) harness
connector B155 terminal 2 (P) and front air control harness con-
nector M49 terminal 15 (P).
OK or NG
OK >> GO TO 6.
NG >> Repair or replace harness as necessary.
6. CHECK PBR FEEDBACK SIGNAL
1. Reconnect front air control connector and air mix door motor
(Rear) connector.
2. Turn ignition switch ON.
3. Check voltage between front air control harness connector M50
terminal 42 (R/Y) and ground.
4. Rotate rear temperature/mode dial (Front) through complete
range.
OK or NG
OK >> Replace front air control. Refer to ATC-135, "FRONT
AIR CONTROL" .
NG >> GO TO 7.3 - 2 Continuity should exist.
LJIA0051E
2 - 15 Continuity should exist.
LJIA0052E
42 - Ground : Approx. 0 - 5V
LJIA0053E

TROUBLE DIAGNOSIS
ATC-75
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Revision: August 20072004 QX56
7. CHECK PBR FEEDBACK CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect air mix door motor (Rear) connector B155 and front
air control connector M50.
3. Check continuity between air mix door motor (Rear) harness
connector B155 terminal 4 (R/Y) and front air control harness
connector M50 terminal 42 (R/Y).
OK or NG
OK >> Replace air mix door motor (Rear) ATC-154, "REAR AIR
MIX DOOR MOTOR" .
NG >> Repair or replace harness as necessary.4 - 42 Continuity should exist.LJIA0054E

TROUBLE DIAGNOSIS
ATC-77
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Revision: August 20072004 QX56
SYSTEM DESCRIPTION
Component Parts
Intake door control system components are:

Front air control

Intake door motor

PBR (built into intake door motor)

In-vehicle sensor

Ambient sensor

Optical sensor

Intake sensor
System Operation
The intake door control determines the intake door position based on the position of the recirculation switch.
When the recirculation switch is depressed the intake door motor rotates closing off the fresh air inlet and
recirculating the cabin air. If the recirculation switch is depressed again, the intake door motor rotates in the
opposite direction, again allowing fresh air into the cabin.
In the AUTO mode, the front air control determines the intake door position based on the ambient tempera-
ture, the intake air temperature and the in-vehicle temperature. When the DEFROST, or OFF switches are
pushed or A/C switch is OFF, the front air control sets the intake door at the fresh position.
Intake Door Control Specification
WJIA0960E
WJIA0436E

ATC-78
TROUBLE DIAGNOSIS
Revision: August 20072004 QX56
COMPONENT DESCRIPTION
Intake door motor
The intake door motor is attached to the intake unit. It rotates so that
air is drawn from inlets set by the front air control. Motor rotation is
conveyed to a lever which activates the intake door.
DIAGNOSTIC PROCEDURE FOR INTAKE DOOR MOTOR
1. CHECK RESULT FROM FRONT AIR CONTROL SELF-DIAGNOSIS
Self-diagnosis code 72 is present. Refer to ATC-53, "
A/C System Self-diagnosis Function" .
YES or NO
YES >> GO TO 2.
NO >> Replace front air control. Refer to ATC-135, "
FRONT AIR CONTROL" .
2. CHECK POWER SUPPLY CIRCUIT FOR INTAKE DOOR MOTOR
1. Turn ignition switch OFF.
2. Disconnect front air control connector M49 and intake door
motor connector M58.
3. Check continuity between front air control harness connector
M49 terminal 7 (O) and intake door motor harness connector
M58 terminal 1 (O) and between front air control harness con-
nector M49 terminal 8 (G/B) and intake door motor harness con-
nector M58 terminal 6 (G/B).
OK or NG
OK >> Replace intake door motor. Refer to ATC-151, "INTAKE DOOR MOTOR" .
NG >> Repair or replace harness as necessary.
WJIA0552E
7 - 1 Continuity should exist.
8 - 6 Continuity should exist.
WJIA0591E

ATC-80
TROUBLE DIAGNOSIS
Revision: August 20072004 QX56
SYSTEM DESCRIPTION
Component Parts
Defroster door control system components are:

Front air control

Defroster door motor

PBR (Built into defroster door motor)

In-vehicle sensor

Ambient sensor

Optical sensor

Intake sensor
System Operation
The front air control determines defroster door position based on the position of the defroster switch. When the
defroster switch is rotated counterclockwise, the defroster door motor rotates directing air to the defroster
ducts. When any mode other than defroster is selected, the defroster motor rotates in the opposite direction
closing off air flow to the defroster ducts.
In the AUTO mode, the front air control determines defroster door position based on the ambient temperature,
the intake air temperature and the in-vehicle temperature.
COMPONENT DESCRIPTION
Defroster door motor
The defroster door motor is attached to the front heater & cooling
unit. The front air control sends a voltage to rotate to the defroster
door directing the air flow either to the defroster ducts, or to the floor
ducts, depending on which way the voltage and ground are applied
to the motor leads. Motor rotation is conveyed to a lever which acti-
vates the defroster door.
WJIA0961E
WJIA0592E

TROUBLE DIAGNOSIS
ATC-81
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Revision: August 20072004 QX56
DIAGNOSTIC PROCEDURE FOR DEFROSTER DOOR MOTOR
1. CHECK RESULT FROM FRONT AIR CONTROL SELF-DIAGNOSIS
Self-diagnosis code 62 is present. Refer to ATC-53, "
A/C System Self-diagnosis Function" .
YES or NO
YES >> GO TO 2.
NO >> GO TO 3.
2. CHECK POWER SUPPLY CIRCUIT FOR DEFROSTER DOOR MOTOR
1. Turn ignition switch OFF.
2. Disconnect front air control connector M49 and defroster door
motor connector M144.
3. Check continuity between front air control harness connector
M49 terminal 19 (LG) and defroster door motor harness connec-
tor M144 terminal 1 (LG) and between front air control harness
connector M49 terminal 20 (P/B) and defroster door motor con-
nector M144 terminal 6 (P/B).
OK or NG
OK >> Replace defroster door motor. Refer to ATC-150, "Removal and Installation" .
NG >> Repair or replace harness as necessary.
3. CHECK PBR REFERENCE SIGNAL VOLTAGE
1. Disconnect defroster door motor harness connector M144.
2. Turn ignition switch ON.
3. Check voltage between defroster door motor harness connector
M144 terminal 3 (Y) and ground.
OK or NG
OK >> GO TO 5.
NG >> GO TO 4.
4. CHECK PBR REFERENCE VOLTAGE CIRCUIT BETWEEN DEFROSTER DOOR MOTOR AND FRONT
AIR CONTROL
1. Turn ignition switch OFF.
2. Disconnect front air control connector M49.
3. Check continuity between defroster door motor harness connec-
tor M144 terminal 3 (Y) and front air control harness connector
M49 terminal 2 (Y).
OK or NG
OK >> Replace front air control. Refer to ATC-135, "FRONT
AIR CONTROL" .
NG >> Repair or replace harness as necessary.19 - 1 : Continuity should exist.
20 - 6 : Continuity should exist.
WJIA0553E
3 - Ground : Approx. 5V
WJIA0554E
3 - 2 : Continuity should exist.
WJIA0555E

ATC-82
TROUBLE DIAGNOSIS
Revision: August 20072004 QX56
5. CHECK PBR GROUND REFERENCE CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect front air control connector M49.
3. Check continuity between defroster door motor harness connec-
tor M144 terminal 2 (P) and front air control harness connector
M49 terminal 15 (P).
OK or NG
OK >> GO TO 6.
NG >> Repair or replace harness as necessary.
6. CHECK PBR FEEDBACK SIGNAL
1. Reconnect front air control connector and defroster door motor
connector.
2. Turn ignition switch ON.
3. Check voltage between front air control harness connector M49
terminal 25 (LG/B) and ground.
4. Change mode between floor, defroster, and panel.
OK or NG
OK >> Replace front air control. Refer to ATC-135, "FRONT
AIR CONTROL" .
NG >> GO TO 7.
7. CHECK PBR FEEDBACK CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect defroster door motor connector M144 and front air
control connector M49.
3. Check continuity between defroster door motor harness connec-
tor M144 terminal 4 (LG/B) and front air control harness connec-
tor M49 terminal 25 (LG/B).
OK or NG
OK >> Replace defroster door motor. Refer to ATC-150,
"Removal and Installation" .
NG >> Repair or replace harness as necessary.2 - 15 : Continuity should exist.
WJIA0556E
25 - Ground : Approx. 0 - 5V
WJIA0770E
4 - 25 : Continuity should exist.
WJIA0558E

ATC-84
TROUBLE DIAGNOSIS
Revision: August 20072004 QX56
SYSTEM DESCRIPTION
Component Parts
Blower speed control system components are:

Front air control

Front blower motor

In-vehicle sensor

Ambient sensor

Optical sensor

Intake sensor
System Operation
Automatic Mode
In the automatic mode, the blower motor speed is calculated by the front air control and variable blower control
based on input from the in-vehicle sensor, optical sensor, intake sensor and ambient sensor, and potentio tem-
perature control (PTC).
When the air flow is increased, the duty ratio of the blower motor′s drive signal is changed at 8%/sec. to pre-
vent a sudden increase in air flow.
In addition to manual air flow control and the usual automatic air flow control, starting air flow control, low
water temperature starting control and high passenger compartment temperature starting control are avail-
able.
Starting Blower Speed Control
Start up from cold soak condition (Automatic mode).
In a cold start up condition where the engine coolant temperature is below 50°C (122°F), the blower will not
operate at blower speed 1 for a short period of time (up to 210 seconds). The exact start delay time varies
depending on the ambient and engine coolant temperatures.
In the most extreme case (very low ambient temperature) the blower starting delay will be 210 seconds as
described above. After the coolant temperature reaches 50°C (122°F), or the 210 seconds has elapsed, the
blower speed will increase to the objective blower speed.
Start up from normal operating or hot soak condition (Automatic mode).
The blower will begin operation momentarily after the AUTO switch is pushed. The blower speed will gradually
rise to the objective speed over a time period of 3 seconds or less (actual time depends on the objective
blower speed).
WJIA0440E