2006 INFINITI QX56 sensor

ATC-118
TROUBLE DIAGNOSIS
Revision: November 20092006 QX56
6. CHECK CIRCUIT CONTINUITY BETWEEN BCM AND FRONT AIR CONTROL
1. Turn ignition switch OFF.
2. Disconnect BCM connector and front air control connector.
3. Check continuity between BCM harness connector M18 terminal 27 and front air control harness connector M49 terminal 12.
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 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-144,
"FRONT AIR CONTROL" .
NG-2 >> If the voltage is approx. 0V when A/C switch is OFF, replace BCM. Refer to BCS-20, "
BCM" .
8. CHECK REFRIGERANT PRESSURE SENSOR
WITH CONSULT-II
1. Start engine.
2. Check voltage of refrigerant pressure sensor. Refer to AT C - 3 4 , "
CONSULT-II Function (HVAC)" .
WITHOUT CONSULT-II
1. Start engine.
2. Check voltage between ECM harness connector F54 terminal 70 and ground.
OK or NG
OK >>
WITH CONSULT-II
GO TO 9.

WITHOUT CONSULT-II
GO TO 10.
NG >> Refer to EC-630, "
REFRIGERANT PRESSURE SENSOR" .
27 - 12 Continuity should exist.
WJIA1443E
Terminals
Condition Voltage
(+)
(-)
Front air
control con-
nector Terminal No.
M49 12 Ground A/C switch: ON Approx. 0V
A/C switch: OFF Approx. 5V
WJIA0449E
Te r m i n a l s
ConditionVoltage
(+)
(-)
ECM con-
nector Terminal No.
F54 70 Ground A/C switch: ON Approx. 0.36 - 3.88V
LJIA0124E

ATC-126
TROUBLE DIAGNOSIS
Revision: November 20092006 QX56
High-pressure Side is Too Low and Low-pressure Side is Too High
Both High- and Low-pressure Sides are Too Low
Gauge indicationRefrigerant cycleProbable causeCorrective action
High-pressure side is too low and
low-pressure side is too high. High- and low-pressure sides
become equal soon after com-
pressor operation stops.Compressor pressure opera-
tion is improper.
↓
Damaged inside compressor
packings.
Replace compressor.
No temperature difference
between high- and low-pres-
sure sides. Compressor pressure opera-
tion is improper.
↓
Damaged inside compressor
packings.
Replace compressor.
AC356A
Gauge indication
Refrigerant cycleProbable causeCorrective action
Both high- and low-pressure sides
are too low.

There is a big temperature
difference between liquid
tank outlet and inlet. Outlet
temperature is extremely
low.

Liquid tank inlet and expan-
sion valve are frosted. Liquid tank inside is slightly
clogged.

Replace liquid tank.

Check oil for contamination.

Temperature of expansion
valve inlet is extremely low
as compared with areas
near liquid tank.

Expansion valve inlet may
be frosted.

Temperature difference
occurs somewhere in high-
pressure side.High-pressure pipe located
between liquit tank and expan-
sion valve is clogged.

Check and repair malfunc-
tioning parts.

Check oil for contamination.
Expansion valve and liquid
tank are warm or only cool
when touched. Low refrigerant charge.
↓
Leaking fittings or compo-
nents.Check refrigerant system for
leaks. Refer to AT C - 1 8 7 ,
"Checking for Refrigerant
Leaks" .
There is a big temperature dif-
ference between expansion
valve inlet and outlet while the
valve itself is frosted. Expansion valve closes a little
compared with the specifica-
tion.
↓
1. Improper expansion valve
adjustment.
2. Malfunctioning expansion valve.
3. Outlet and inlet may be clogged.

Remove foreign particles by
using compressed air.

Check oil for contamination.
An area of the low-pressure
pipe is colder than areas near
the evaporator outlet. Low-pressure pipe is clogged
or crushed.

Check and repair malfunc-
tioning parts.

Check oil for contamination.
Air flow volume is too low. Evaporator is frozen.

Check intake sensor circuit.
Refer to ATC-142, "
Intake
Sensor Circuit" .

Repair evaporator fins.

Replace evaporator.

Refer to AT C - 9 3 , "Front
Blower Motor Circuit" .
AC353A

ATC-128
TROUBLE DIAGNOSIS
Revision: November 20092006 QX56
Insufficient HeatingEJS003XX
SYMPTOM: Insufficient heating
INSPECTION FLOW
*1ATC-58, "Operational Check (Front)"
or AT C - 6 0 , "
Operational Check
(Rear)"
*2 AT C - 7 0 , "Air Mix Door Motor Circuit"*3ATC-56, "A/C System Self-diagno-
sis Function"
*4 ATC-57, "SELF-DIAGNOSIS CODE
CHART"
*5AT C - 9 3 , "Front Blower Motor Circuit"*6EC-192, "DTC P0117, P0118 ECT
SENSOR"
*7 EM-13, "Checking Drive Belts"*8ATC-132, "Water Valve Circuit"
WJIA1889E

ATC-130
TROUBLE DIAGNOSIS
Revision: November 20092006 QX56
Self-diagnosisEJS003XZ
SYMPTOM: Self-diagnosis cannot be performed.
INSPECTION FLOW
*1ATC-61, "Power Supply and Ground
Circuit for Front Air Control"
*2 ATC-134, "Ambient Sensor Circuit"*3ATC-140, "In-vehicle Sensor"
*4ATC-140, "Optical Sensor Circuit"*5 ATC-142, "Intake Sensor Circuit"*6AT C - 7 0 , "Air Mix Door Motor Circuit"
*7ATC-58, "Operational Check (Front)"*8 ATC-39, "SYMPTOM TABLE"
WJIA1063E

ATC-134
TROUBLE DIAGNOSIS
Revision: November 20092006 QX56
Ambient Sensor CircuitEJS003Y2
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. Using the
CONSULT-II, DTC B257B or B257C is displayed. Without a CON-
SULT-II, code 40 or 41 is indicated on front air control as a result of
conducting the front air control self-diagnosis.
1. CHECK VOLTAGE BETWEEN AMBIENT SENSOR AND GROUND
1. Disconnect ambient sensor connector.
2. Turn ignition switch ON.
3. Check voltage between ambient sensor harness connector E1 terminal 1 and ground.
OK or NG
OK >> GO TO 2.
NG >> GO TO 4.
WJIA0819E
WJIA0456E
1 - Ground : Approx. 5V
WJIA1273E

TROUBLE DIAGNOSISATC-135
C
DE
F
G H
I
K L
M A
B
AT C
Revision: November 2009 2006 QX56
2. CHECK CIRCUIT CONTINUITY BETWEEN AMBIENT SENSOR AND FRONT AIR CONTROL
1. Turn ignition switch OFF.
2. Disconnect front air control connector.
3. Check continuity between ambient sensor harness connector E1 terminal 1 and front air control harness connector M49 termi-
nal 17.
OK or NG
OK >> GO TO 3.
NG >> Repair harness or connector.
3. CHECK AMBIENT SENSOR
Refer to ATC-134, "
Ambient Sensor Circuit" .
OK or NG
OK >> 1. Replace front air control. Refer to ATC-144, "FRONT AIR CONTROL"
2. Go to AT C - 5 6 , "A/C System Self-diagnosis Function" and perform self-diagnosis.
NG >> 1. Replace ambient sensor. Refer to ATC-145, "
AMBIENT SENSOR" .
2. Go to AT C - 5 6 , "
A/C System Self-diagnosis Function" and perform self-diagnosis.
4. CHECK CIRCUIT CONTINUITY BETWEEN AMBIENT SENSOR AND FRONT AIR CONTROL
1. Turn ignition switch OFF.
2. Disconnect front air control connector.
3. Check continuity between ambient sensor harness connector E1 terminal 2 and front air control harness connector M49 termi-
nal 21.
4. Check continuity between ambient sensor harness connector E1 terminal 2 and ground.
OK or NG
OK >> 1. Replace front air control. Refer to ATC-144, "FRONT AIR CONTROL"
2. Go to self-diagnosis AT C - 5 6 , "A/C System Self-diagnosis Function" and perform self-diagno-
sis.
NG >> Repair harness or connector. 1 - 17
: Continuity should exist.
WJIA0564E
2 - 21: Continuity should exist.
2 - Ground : Continuity should not exist.
WJIA0565E

ATC-136
TROUBLE DIAGNOSIS
Revision: November 20092006 QX56
COMPONENT INSPECTION
Ambient Sensor
After disconnecting ambient sensor (1) connector E1, measure
resistance between terminals 1 and 2 at sensor component side,
using the table below.
If NG, replace ambient sensor.
Temperature °C (°F) Resistance kΩ
− 15 (5) 12.73
− 10 (14) 9.92
− 5 (23) 7.80
0 (32) 6.19
5 (41) 4.95
10 (50) 3.99
15 (59) 3.24
20 (68) 2.65
25 (77) 2.19
30 (86) 1.81
35 (95) 1.51
40 (104) 1.27
45 (113) 1.07
WJIA1975E

TROUBLE DIAGNOSISATC-137
C
DE
F
G H
I
K L
M A
B
AT C
Revision: November 2009 2006 QX56
In-vehicle Sensor CircuitEJS003Y3
COMPONENT DESCRIPTION
In-vehicle Sensor
The in-vehicle sensor is located on cluster lid D. It converts varia-
tions in temperature of passenger compartment air (drawn in through
the integrated fan) into a resistance value. It is then input into the
front air control.
WJIA0822E
WJIA0606E