INFINITI QX4 2005 Factory Service Manual

ATC-126
TROUBLE DIAGNOSIS
Revision: October 20052005 QX56
High-pressure Side is Too Low and Low-pressure Side is Too High
Both High- and Low-pressure Sides are Too Low
Gauge indication Refrigerant cycle Probable cause Corrective 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 cycle Probable cause Corrective 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 lubricant for contami-
nation.

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 lubricant for contami-
nation.
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 ATC-189,
"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 lubricant for contami-
nation.
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 lubricant for contami-
nation.
Air flow volume is too low. Evaporator is frozen.

Check intake sensor circuit.
Refer to ATC-145, "
Intake
Sensor Circuit" .

Repair evaporator fins.

Replace evaporator.

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

TROUBLE DIAGNOSIS
ATC-127
C
D
E
F
G
H
I
K
L
MA
B
AT C
Revision: October 20052005 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

ATC-128
TROUBLE DIAGNOSIS
Revision: October 20052005 QX56
Insufficient HeatingEJS003XX
SYMPTOM: Insufficient heating
INSPECTION FLOW
*1ATC-57, "Operational Check (Front)"
or ATC-60, "
Operational Check
(Rear)"
*2AT C - 7 0 , "Air Mix Door Motor Circuit"*3AT C - 5 5 , "A/C System Self-diagno-
sis Function"
*4ATC-56, "SELF-DIAGNOSIS CODE
CHART"
*5AT C - 9 3 , "Front Blower Motor Circuit"*6EC-195, "DTC P0117, P0118 ECT
SENSOR"
*7EM-12, "Checking Drive Belts"*8ATC-133, "Water Valve Circuit"
WJIA1372E

TROUBLE DIAGNOSIS
ATC-129
C
D
E
F
G
H
I
K
L
MA
B
AT C
Revision: October 20052005 QX56
NoiseEJS003XY
SYMPTOM: Noise

ATC-130
TROUBLE DIAGNOSIS
Revision: October 20052005 QX56
INSPECTION FLOW
WJIA0473E

TROUBLE DIAGNOSIS
ATC-131
C
D
E
F
G
H
I
K
L
MA
B
AT C
Revision: October 20052005 QX56
*1ATC-179, "REMOVAL"*2ATC-180, "INSTALLATION"*3AT C - 2 2 , "Maintenance of Lubricant
Quantity in Compressor"
*4ATC-57, "Operational Check (Front)"
or AT C - 6 0 , "
Operational Check
(Rear)"
*5EM-12, "Checking Drive Belts"

ATC-132
TROUBLE DIAGNOSIS
Revision: October 20052005 QX56
Self-diagnosisEJS003XZ
SYMPTOM: Self-diagnosis cannot be performed.
INSPECTION FLOW
*1AT C - 6 1 , "Power Supply and Ground
Circuit for Front Air Control"
*2ATC-137, "Ambient Sensor Circuit"*3ATC-145, "Intake Sensor Circuit"
*4ATC-143, "Optical Sensor Circuit"*5ATC-145, "Intake Sensor Circuit"*6AT C - 7 0 , "Air Mix Door Motor Circuit"
*7AT C - 5 7 , "Operational Check (Front)"*8ATC-38, "SYMPTOM TABLE"
WJIA1063E

TROUBLE DIAGNOSIS
ATC-133
C
D
E
F
G
H
I
K
L
MA
B
AT C
Revision: October 20052005 QX56
Memory FunctionEJS003Y0
SYMPTOM: Memory function does not operate.
INSPECTION FLOW
Water Valve CircuitEJS003Y1
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-61, "Power Supply and Ground
Circuit for Front Air Control"
*2AT C - 5 7 , "Operational Check (Front)"*3AT C - 5 5 , "A/C System Self-diagnosis
Function"
*4ATC-56, "SELF-DIAGNOSIS CODE
CHART"
WJIA1287E
WJIA1015E

ATC-134
TROUBLE DIAGNOSIS
Revision: October 20052005 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. 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-147, "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/R)
GroundBattery voltage Battery voltage
3 (Y/G) 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-135
C
D
E
F
G
H
I
K
L
MA
B
AT C
Revision: October 20052005 QX56
4. CHECK WATER VALVE RELAY
Check water valve relay. Refer to ATC-136, "
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 F68.
3. Check continuity between water valve harness connector F68
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 F68 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.
WJIA1373E
5 - + : Continuity should exist.
5 - Ground : Continuity should not exist.
WJIA0903E