2004 INFINITI QX56 Air

TROUBLE DIAGNOSIS
ATC-103
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Revision: August 20072004 QX56
2. CHECK CIRCUIT BETWEEN REAR AIR CONTROL AND FRONT AIR CONTROL FOR OPEN AND
SHORT
1. Turn ignition switch OFF.
2. Disconnect front air control M50 and rear temperature/mode dial
(rear) (Rear air control) connector R209.
3. Check continuity between front air control harness connector
M50 terminal 33 (V) and rear temperature/mode dial (rear)
(Rear air control) connector R209 terminal 5 (V).
4. Check continuity between rear temperature/mode dial (rear)
(Rear air control) connector R209 terminal 5 (V) and ground.
OK or NG
OK >> GO TO 3.
NG >> Repair harness or connector.
3. CHECK CIRCUIT BETWEEN REAR AIR CONTROL AND AIR MIX DOOR MOTOR (REAR) FOR OPEN
OR SHORT
1. Disconnect air mix door motor (rear) connector B155.
2. Check continuity between rear temperature/mode dial (rear)
(Rear air control) connector R209 terminal 2 (P) and 4 (Y) and
air mix door motor (rear) harness connector B155 terminal 2 (P)
and 3 (Y).
3. Check continuity between rear temperature/mode dial (rear)
(Rear air control) connector R209 terminals 2 (P) and 4 (Y) and
ground.
OK or NG
OK >> Replace rear air control [rear temperature/mode dial (rear)]. Refer to ATC-135, "REAR AIR CON-
TROL" .
NG >> Repair harness or connector.33 - 5 Continuity should exist.
5 - Ground Continuity should not exist.
WJIA0803E
2 - 2 Continuity should exist.
4 - 3 Continuity should exist.
2, 4 - Ground Continuity should not exist.
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TROUBLE DIAGNOSIS
ATC-105
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Revision: August 20072004 QX56
SYSTEM DESCRIPTION
The front air control controls compressor operation based on ambient and intake temperature and a signal
from ECM.
Low Temperature Protection Control
The front air control will turn the compressor ON or OFF as determined by a signal detected by the intake sen-
sor and the ambient sensor.
When intake air temperature is higher than the preset value, the compressor turns ON. The compressor turns
OFF when intake air temperature is lower than the preset value. That preset value is dependent on the ambi-
ent temperature, refer to the following table.
DIAGNOSTIC PROCEDURE FOR MAGNET CLUTCH
SYMPTOM: Magnet clutch does not engage when A/C switch is ON.
1. CHECK INTAKE AND AMBIENT SENSOR CIRCUITS
Check intake and ambient sensors. Refer to ATC-53, "
A/C System Self-diagnosis Function" .
OK or NG
OK >> GO TO 2.
NG >>

Malfunctioning intake sensor. Refer to ATC-133, "Intake Sensor Circuit" .

Malfunctioning ambient sensor. Refer to ATC-125, "Ambient Sensor Circuit" .
Ambient temperature °C (°F)Co mp re s so r ON
intake temperature °C (°F)C o m p r e s s o r O F F
intake temperature °C (°F)
0 (32) 5.5 (41.9) 5.0 (41.0)
10 (50) 4.5 (40.1) 4.0 (39.2)
20 (68) 2.5 (36.5) 2.0 (35.6)
30 (86) 2.0 (35.6) 1.0 (33.8)
40 (104) 2.0 (35.6) 0.5 (32.9)
50 (122) 2.0 (35.6) 0.5 (32.9)
WJIA1369E

ATC-106
TROUBLE DIAGNOSIS
Revision: August 20072004 QX56
2. PERFORM AUTO ACTIVE TEST
Refer to PG-23, "
Auto Active Test" .
Does magnet clutch operate?
YES or NO
YES >>
WITH CONSULT-II
GO TO 5.

WITHOUT CONSULT-II
GO TO 6.
NO >> Check 10A fuse (No. 42, located in IPDM E/R), and GO TO 3.
3. CHECK CIRCUIT CONTINUITY BETWEEN IPDM E/R AND COMPRESSOR
1. Turn ignition switch OFF.
2. Disconnect IPDM E/R connector E119 and compressor (magnet
clutch) connector F3.
3. Check continuity between IPDM E/R harness connector E119
terminal 11 (Y/B) and compressor harness connector F3 termi-
nal 1 (Y/B).
OK or NG
OK >> GO TO 4.
NG >> Repair harness or connector.
4. CHECK MAGNET CLUTCH CIRCUIT
Check for operation sound when applying battery voltage direct cur-
rent to terminal.
OK or NG
OK >> Replace IPDM E/R. Refer to PG-29, "Removal and
Installation of IPDM E/R" .
NG >> Replace magnet clutch. Refer to ATC-167, "
Removal
and Installation for Compressor Clutch" .
5. CHECK BCM INPUT (COMPRESSOR ON) SIGNAL
Check compressor ON/OFF signal. Refer to AT C - 3 3 , "
CONSULT-II
Function (BCM)" .
OK or NG
OK >> GO TO 8.
NG >> GO TO 6.
11 – 1 : Continuity should exist.
WJIA0808E
SJIA0197E
A/C SW ON : COMP ON SIG ON
A/C SW OFF : COMP ON SIG OFF
WJIA0469E

TROUBLE DIAGNOSIS
ATC-107
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Revision: August 20072004 QX56
6. CHECK CIRCUIT CONTINUITY BETWEEN BCM AND FRONT AIR CONTROL
1. Turn ignition switch OFF.
2. Disconnect BCM connector M18 and front air control connector
M49.
3. Check continuity between BCM harness connector M18 terminal
27 (W/R) and front air control harness connector M49 terminal
12 (W/R).
OK or NG
OK >> GO TO 7.
NG >> Repair harness or connector.
7. CHECK VOLTAGE FOR FRONT AIR CONTROL (COMPRESSOR ON SIGNAL)
1. Reconnect BCM connector and front air control connector.
2. Turn ignition switch ON.
3. Check voltage between front air control harness connector M49
terminal 12 (W/R) and ground.
OK or NG
OK >> GO TO 8.
NG-1 >> If the voltage is approx. 5V when A/C switch is ON, replace front air control. Refer to ATC-135,
"FRONT AIR CONTROL" .
NG-2 >> If the voltage is approx. 0V when A/C switch is OFF, replace BCM. Refer to BCS-19, "
Removal
and Installation of BCM" . 27 - 12 Continuity should exist.
WJIA0809E
Te r m i n a l s
ConditionVoltag e
(Approx.) (+)
(-) Front air
control con-
nectorTe r m i n a l N o .
(Wire color)
M49 12 (W/R) GroundA/C switch: ON 0V
A/C switch: OFF 5V
WJIA0449E

ATC-108
TROUBLE DIAGNOSIS
Revision: August 20072004 QX56
8. CHECK REFRIGERANT PRESSURE SENSOR
WITH CONSULT-II
1. Start engine.
2. Check voltage of refrigerant pressure sensor. Refer to AT C - 3 3 , "
CONSULT-II Function (BCM)" .
WITHOUT CONSULT-II
1. Start engine.
2. Check voltage between ECM harness connector F54 terminal
70 (B/W) and ground.
OK or NG
OK >>
WITH CONSULT-II
GO TO 9.

WITHOUT CONSULT-II
GO TO 10.
NG >> Refer to EC-607, "
REFRIGERANT PRESSURE SENSOR" .
9. CHECK BCM INPUT (FAN ON) SIGNAL
Check FAN ON/OFF signal while changing the front switch position.
Refer to ATC-33, "
CONSULT-II Function (BCM)" .
OK or NG
OK >> GO TO 12.
NG >> GO TO 10.
10. CHECK CIRCUIT CONTINUITY BETWEEN BCM AND FRONT AIR CONTROL
1. Turn ignition switch OFF.
2. Disconnect BCM connector M18 and front air control connector
M49.
3. Check continuity between BCM harness connector M18 terminal
28 (L/R) and front air control harness connector M49 terminal 10
(L/R).
OK or NG
OK >> GO TO 11.
NG >> Repair harness or connector.
Te r m i n a l s
Condition Voltage (+)
(-)
ECM con-
nectorTe r m i n a l N o .
(Wire color)
F54 70 (B/W) Ground A/C switch: ON Approx. 0.36 - 3.88V
LJIA0124E
FRONT FAN SWITCH ON : FAN ON SIG ON
FRONT FAN SWITCH OFF : FAN ON SIG OFF
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28 - 10 Continuity should exist.
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TROUBLE DIAGNOSIS
ATC-109
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Revision: August 20072004 QX56
11 . CHECK VOLTAGE FOR FRONT AIR CONTROL (FAN ON SIGNAL)
1. Reconnect BCM connector and front air control connector.
2. Turn ignition switch ON.
3. Check voltage between front air control harness connector M49
terminal 10 (L/R) and ground.
OK or NG
OK >> Check CAN communication. Refer to ATC-32, "CAN Communication System Description" .
NG-1 >> If the voltage is approx. 5V when blower motor is ON, replace front air control. Refer to ATC-135,
"FRONT AIR CONTROL" .
NG-2 >> If the voltage is approx. 0V when blower motor is OFF, replace BCM. Refer to BCS-19, "
Removal
and Installation of BCM" .
Te r m i n a l s
ConditionVo ltag e
(Approx.) (+)
(-)
Front air con-
trol connectorTe r m i n a l N o .
(Wire color)
M49 10 (L/R) GroundA/C switch: ON
Blower motor
operates0V
A/C switch: OFF 5V
WJIA0451E

TROUBLE DIAGNOSIS
ATC-111
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Revision: August 20072004 QX56
PERFORMANCE TEST DIAGNOSES
*1ATC-113, "PERFORMANCE
CHART"
*2AT C - 11 3 , "PERFORMANCE
CHART"
*3AT C - 11 4 , "Trouble Diagnoses for
Unusual Pressure"
*4ATC-67, "Air Mix Door Motor Circuit"
RJIA1601E

TROUBLE DIAGNOSIS
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Revision: August 20072004 QX56
PERFORMANCE CHART
Test Condition
Testing must be performed as follows:
Te s t R e a d i n g
Recirculating-to-discharge Air Temperature Table
Ambient Air Temperature-to-operating Pressure Table
Vehicle location Indoors or in the shade (in a well-ventilated place)
Doors Closed
Door window Open
Hood Open
TEMP. Max. COLD
Mode switch
(Ventilation) set
Recirculation (REC) switch
(Recirculation) set
Fan (blower) speedMax. speed set
Engine speed Idle speed
Operate the air conditioning system for 10 minutes before taking measurements.
Inside air (Recirculating air) at blower assembly inlet
Discharge air temperature at center ventilator
°C (°F) Relative humidity
%Air temperature
°C (°F)
50 - 6020 (68) 5.3 - 6.5 (42 - 44)
25 (77) 9.7 - 11.5 (49 - 53)
30 (86) 13.8 - 16.3 (57 - 61)
35 (95) 18.0 - 21.2 (64 - 70)
40 (104) 22.2 - 25.7 (72 - 78)
60 - 7020 (68) 6.5 - 7.7 (44 - 46)
25 (77) 11.5 - 13.3 (53 - 56)
30 (86) 16.3 - 18.8 (61 - 66)
35 (95) 21.2 - 24.0 (70 - 75)
40 (104) 25.7 - 29.2 (78 - 85)
Ambient air
High-pressure (Discharge side)
kPa (kg/cm
2 , psi)Low-pressure (Suction side)
kPa (kg/cm2 , psi) Relative humidity
%Air temperature
°C (°F)
50 - 7020 (68)680 - 840
(6.94 - 8.57, 98.6 - 121.8)160 - 198
(1.63 - 2.02, 23.2 - 28.7)
25 (77)800 - 985
(8.16 - 10.05, 116.0 - 142.8)198 - 245
(2.02 - 2.50, 28.7 - 35.5)
30 (86)940 - 1,150
(9.59 - 11.73, 136.3 - 166.8)225 - 278
(2.30 - 2.84, 32.6 - 40.3)
35 (95)1,160 - 1,410
(11.83 - 14.38, 168.2 - 204.5)273 - 335
(2.78 - 3.42, 39.6 - 48.6)
40 (104)1,325 - 1,620
(13.52 - 16.52, 192.1 - 234.9)325 - 398
(3.32 - 4.06, 47.1 - 57.7)