INFINITI QX56 2004 Factory Service Manual

ATC-116
TROUBLE DIAGNOSIS
Revision: August 20072004 QX56
Low-pressure Side Sometimes Becomes Negative
Low-pressure Side Becomes Negative
Gauge indication Refrigerant cycle Probable cause Corrective action
Low-pressure side sometimes
becomes negative.

Air conditioning system
does not function and does
not cyclically cool the com-
partment air.

The system constantly func-
tions for a certain period of
time after compressor is
stopped and restarted.Refrigerant does not dis-
charge cyclically.
↓
Moisture is frozen at expan-
sion valve outlet and inlet.
↓
Water is mixed with refriger-
ant.

Drain water from refrigerant
or replace refrigerant.

Replace liquid tank.
AC354A
Gauge indication Refrigerant cycle Probable cause Corrective action
Low-pressure side becomes nega-
tive.
Liquid tank or front/rear side of
expansion valve′s pipe is
frosted or dewed.High-pressure side is closed
and refrigerant does not flow.
↓
Expansion valve or liquid tank
is frosted.Leave the system at rest until
no frost is present. Start it
again to check whether or not
the malfunction is caused by
water or foreign particles.

If water is the cause, initially
cooling is okay. Then the
water freezes causing a
blockage. Drain water from
refrigerant or replace refrig-
erant.

If due to foreign particles,
remove expansion valve
and remove the particles
with dry and compressed air
(not shop air).

If either of the above meth-
ods cannot correct the mal-
function, replace expansion
valve.

Replace liquid tank.

Check lubricant for contami-
nation.
AC362A

TROUBLE DIAGNOSIS
ATC-117
C
D
E
F
G
H
I
K
L
MA
B
AT C
Revision: August 20072004 QX56
Insufficient HeatingEJS002CN
SYMPTOM: Insufficient heating
INSPECTION FLOW
*1 .ATC-56, "Operational Check
(Front)" or AT C - 5 9 , "Operational
Check (Rear)"
*2AT C - 6 7 , "Air Mix Door Motor Circuit"*3AT C - 5 3 , "A/C System Self-diagno-
sis Function"
*4AT C - 5 3 , "A/C System Self-diagnosis
Function"
*5AT C - 8 3 , "Front Blower Motor Circuit"*6EC-165, "DTC P0117, P0118 ECT
SENSOR"
*7MA-12, "Changing Engine Coolant"*8CO-8, "CHECKING RESERVOIR
CAP"
*9ATC-121, "Water Valve Circuit"
*10CO-4, "OVERHEATING CAUSE
ANALYSIS"
WJIA0812E

ATC-118
TROUBLE DIAGNOSIS
Revision: August 20072004 QX56
NoiseEJS002CO
SYMPTOM: Noise
INSPECTION FLOW
WJIA0473E

TROUBLE DIAGNOSIS
ATC-119
C
D
E
F
G
H
I
K
L
MA
B
AT C
Revision: August 20072004 QX56
*1ATC-167, "REMOVAL"*2ATC-168, "INSTALLATION"*3AT C - 2 2 , "Maintenance of Lubricant
Quantity in Compressor"
*4ATC-56, "Operational Check (Front)"
or AT C - 5 9 , "
Operational Check
(Rear)"
*5MA-12, "Checking Drive Belts"

ATC-120
TROUBLE DIAGNOSIS
Revision: August 20072004 QX56
Self-diagnosisEJS002CP
SYMPTOM: Self-diagnosis cannot be performed.
INSPECTION FLOW
*1AT C - 6 0 , "Power Supply and Ground
Circuit for Front Air Control"
*2ATC-125, "Ambient Sensor Circuit"*3ATC-128, "In-vehicle Sensor Circuit"
*4ATC-131, "Optical Sensor Circuit"*5ATC-133, "Intake Sensor Circuit"*6AT C - 6 7 , "Air Mix Door Motor Circuit"
*7AT C - 5 6 , "Operational Check (Front)"*8ATC-35, "SYMPTOM TABLE"
WJIA0813E

TROUBLE DIAGNOSIS
ATC-121
C
D
E
F
G
H
I
K
L
MA
B
AT C
Revision: August 20072004 QX56
Memory FunctionEJ S00 2CQ
SYMPTOM: Memory function does not operate.
INSPECTION FLOW
Water Valve CircuitEJS002CR
COMPONENT DESCRIPTION
Water Valve
The water valve cuts the flow of engine coolant to the front and rear
heater cores to allow for maximum cooling during A/C operation. It is
controlled by the front air control through the water valve relay.
*1ATC-60, "Power Supply and Ground
Circuit for Front Air Control"
*2AT C - 5 6 , "Operational Check (Front)"*3AT C - 5 3 , "A/C System Self-diagnosis
Function"
WJIA0797E
WJIA1015E

ATC-122
TROUBLE DIAGNOSIS
Revision: August 20072004 QX56
DIAGNOSTIC PROCEDURE FOR WATER VALVE
1. CHECK WATER VALVE RELAY POWER INPUT CIRCUITS
1. Turn ignition switch OFF.
2. Disconnect water valve relay connector M7.
3. Turn ignition switch ON.
4. Check voltage between water valve relay harness connector ter-
minals and ground.
OK or NG
OK >> GO TO 2.
NG >> Repair harness or connector.
2. CHECK WATER VALVE CONTROL
1. Turn ignition switch ON.
2. Select MAX A/C with mode switch.
3. Check continuity between water valve relay harness connector
M7 terminal 1 (W/G) and ground, as MAX A/C is switched OFF
and ON.
OK or NG
OK >> GO TO 4.
NG >> GO TO 3.
3. CHECK WATER VALVE CONTROL OUTPUT CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect front air control connector M50.
3. Check continuity between water valve relay harness connector
M7 terminal 1 (W/G) and front air control harness connector
M50 terminal 29 (W/G).
4. Check continuity between water valve relay harness connector
M7 terminal 1 (W/G) and ground.
OK or NG
OK >> Replace front air control. Refer to ATC-135, "FRONT AIR CONTROL" .
NG >> Repair harness or connector.
Terminals Ignition switch position
(+)
(-) OFF ON Water valve
relay con-
nectorTe r m i n a l N o .
(Wire color)
M72 (Y/G)
GroundBattery voltage Battery voltage
3 (G/Y) 0V Battery voltage
WJIA0900E
Terminals
Condition Continuity (+)
(-) Water valve
relay con-
nectorTe r m i n a l N o .
(Wire color)
M7 1 (W/G) GroundMAX A/C: ON Yes
MAX A/C: OFF No
WJIA0901E
1 - 29 : Continuity should exist.
1 - Ground : Continuity should not exist.
WJIA0902E

TROUBLE DIAGNOSIS
ATC-123
C
D
E
F
G
H
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K
L
MA
B
AT C
Revision: August 20072004 QX56
4. CHECK WATER VALVE RELAY
Check water valve relay. Refer to ATC-124, "
Wat er Va lve Relay" .
OK or NG
OK >> GO TO 5.
NG >> Replace water valve relay.
5. CHECK WATER VALVE GROUND CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect water valve connector E141.
3. Check continuity between water valve harness connector E141
terminal - (B) and ground.
OK or NG
OK >> GO TO 6.
NG >> Repair harness or connector.
6. CHECK WATER VALVE POWER CIRCUIT
1. Check continuity between water valve relay connector terminal 5
(Y/L) and water valve connector E141 terminal + (Y/L)
2. Check continuity between water valve relay harness connector
M7 terminal 5 (Y/L) and ground.
OK or NG
OK >> Replace water valve.
NG >> Repair harness or connector.(-) - Ground : Continuity should exist.
WJIA0816E
5 - + : Continuity should exist.
5 - Ground : Continuity should not exist.
WJIA0903E

ATC-124
TROUBLE DIAGNOSIS
Revision: August 20072004 QX56
COMPONENT INSPECTION
Water Valve R elay
Check continuity between terminals by supplying 12 volts and
ground to coil side terminals of relay.
WJIA0899E

TROUBLE DIAGNOSIS
ATC-125
C
D
E
F
G
H
I
K
L
MA
B
AT C
Revision: August 20072004 QX56
Ambient Sensor CircuitEJS002CS
COMPONENT DESCRIPTION
Ambient Sensor
The ambient sensor is attached on the radiator core support (left
side). It detects ambient temperature and converts it into a value
which is then input into the front air control.
AMBIENT TEMPERATURE INPUT PROCESS
The front air control includes a processing circuit for the ambient sensor input. However, when the tempera-
ture detected by the ambient sensor increases quickly, the processing circuit retards the front air control func-
tion. It only allows the front air control to recognize an ambient temperature increase of 0.33°C (0.6°F) per 100
seconds.
This prevents constant adjustments due to momentary conditions, such as stopping after high speed driving.
Although the actual ambient temperature has not changed, the temperature detected by the ambient sensor
will increase. This is because the heat from the engine compartment can radiate to the front grille area, loca-
tion of the ambient sensor.
DIAGNOSTIC PROCEDURE FOR AMBIENT SENSOR
SYMPTOM: Ambient sensor circuit is open or shorted. (40 or 41 is
indicated as a result of conducting the front air control self-diagnosis)
1. CHECK VOLTAGE BETWEEN AMBIENT SENSOR AND GROUND
1. Disconnect ambient sensor connector E1.
2. Turn ignition switch ON.
3. Check voltage between ambient sensor harness connector E1
terminal 1 (P) and ground.
OK or NG
OK >> GO TO 2.
NG >> GO TO 4.
WJIA0819E
WJIA0456E
1 - Ground : Approx. 5V
WJIA0966E