cooling INFINITI QX56 2004 Factory Owner's Manual

ATC-110
TROUBLE DIAGNOSIS
Revision: August 20072004 QX56
Insufficient CoolingEJS002CM
SYMPTOM: Insufficient cooling
INSPECTION FLOW
*1 .AT C - 5 6 , "Operational Check
(Front)"
*2AT C - 5 3 , "A/C System Self-diagno-
sis Function"
*3AT C - 5 5 , "SELF-DIAGNOSIS CODE
CHART"
*4 EC-410, "SYSTEM DESCRIPTION"*5AT C - 5 , "Contaminated Refrigerant"*6 .AT C - 111 , "PERFORMANCE TEST
DIAGNOSES"
*7ATC-113, "Test Reading"*8MA-12, "Checking Drive Belts"*9ATC-121, "Water Valve Circuit"
WJIA0963E

ATC-114
TROUBLE DIAGNOSIS
Revision: August 20072004 QX56
TROUBLE DIAGNOSES FOR UNUSUAL PRESSURE
Whenever system′s high and/or low side pressure(s) is/are unusual, diagnose using a manifold gauge. The
marker above the gauge scale in the following tables indicates the standard (usual) pressure range. Since the
standard (usual) pressure, however, differs from vehicle to vehicle, refer to preceding table (Ambient air tem-
perature-to-operating pressure table).
Both High- and Low-pressure Sides are Too High
High-pressure Side is Too High and Low-pressure Side is Too Low
Gauge indication Refrigerant cycle Probable cause Corrective action
Both high- and low-pressure sides
are too high.Pressure is reduced soon
after water is splashed on
condenser.Excessive refrigerant charge
in refrigeration cycleReduce refrigerant until speci-
fied pressure is obtained.
Air suction by cooling fan is
insufficient.Insufficient condenser cooling
performance
↓
1. Condenser fins are clogged.
2. Improper fan rotation of
cooling fan

Clean condenser.

Check and repair cooling fan
as necessary.

Low-pressure pipe is not
cold.

When compressor is
stopped high-pressure
value quickly drops by
approximately 196 kPa (2
kg/cm
2 , 28 psi). It then
decreases gradually there-
after.Poor heat exchange in con-
denser
(After compressor operation
stops, high-pressure
decreases too slowly.)
↓
Air in refrigeration cycleEvacuate and recharge sys-
tem.
Engine tends to overheat.Engine cooling systems mal-
function.Check and repair engine cool-
ing system.

An area of the low-pres-
sure pipe is colder than
areas near the evaporator
outlet.

Plates are sometimes cov-
ered with frost.

Excessive liquid refrigerant
on low-pressure side

Excessive refrigerant dis-
charge flow

Expansion valve is open a
little compared with the
specification.
↓
Improper expansion valve
adjustmentReplace expansion valve.
AC359A
Gauge indication Refrigerant cycle Probable cause Corrective action
High-pressure side is too high and
low-pressure side is too low.
Upper side of condenser and
high-pressure side are hot,
however, liquid tank is not so
hot.High-pressure tube or parts
located between compressor
and condenser are clogged or
crushed.

Check and repair or replace
malfunctioning parts.

Check lubricant for contami-
nation.
AC360A

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-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

TROUBLE DIAGNOSIS
ATC-133
C
D
E
F
G
H
I
K
L
MA
B
AT C
Revision: August 20072004 QX56
Intake Sensor CircuitEJS002CV
COMPONENT DESCRIPTION
Intake Sensor
The intake sensor is located on the front heater & cooling unit. It con-
verts temperature of air after it passes through the evaporator into a
resistance value which is then input to the front air control.
DIAGNOSTIC PROCEDURE FOR INTAKE SENSOR
SYMPTOM: Intake sensor circuit is open or shorted. (56 or 57 is indi-
cated as a result of conducting self-diagnosis).
1. CHECK VOLTAGE BETWEEN INTAKE SENSOR AND GROUND
1. Disconnect intake sensor connector M146.
2. Turn ignition switch ON.
3. Check voltage between intake sensor harness connector M146
terminal 2 (L/B) and ground.
OK or NG
OK >> GO TO 2.
NG >> GO TO 4.
2. CHECK CIRCUIT CONTINUITY BETWEEN INTAKE SENSOR AND FRONT AIR CONTROL
1. Turn ignition switch OFF.
2. Disconnect front air control connector M49.
3. Check continuity between intake sensor harness connector
M146 terminal 1 (V/R) and front air control harness connector
M49 terminal 21 (V/R).
OK or NG
OK >> GO TO 3.
NG >> Repair harness or connector.
WJIA0571E
WJIA0464E
2 - Ground : Approx. 5V
WJIA0829E
1 - 21 : Continuity should exist.
WJIA0830E

INTAKE SENSOR
ATC-139
C
D
E
F
G
H
I
K
L
MA
B
AT C
Revision: August 20072004 QX56
INTAKE SENSORPFP:27723
Removal and InstallationEJS002D0
REMOVAL
1. Remove the instrument panel. Refer to IP-10, "INSTRUMENT PANEL ASSEMBLY" .
2. Disconnect the intake sensor electrical connector.
NOTE:
The intake sensor is located on the top of the front heater and
cooling unit assembly next to the A/C evaporator cover.
3. Twist the intake sensor to remove the intake sensor from the
front heater and cooling unit assembly.
INSTALLATION
Installation is in the reverse order of removal.
LJIA0133E

ATC-140
BLOWER MOTOR
Revision: August 20072004 QX56
BLOWER MOTORPFP:27226
ComponentsEJS002D1
Front Blower Motor
Rear Blower Motor
Removal and InstallationEJS002D2
FRONT BLOWER MOTOR
Removal
1. Remove the glove box assembly. Refer to IP-14, "Instrument Lower Cover RH and Glove Box" .
2. Disconnect the front blower motor electrical connector.
3. Remove the three screws and remove the front blower motor.
Installation
Installation is in the reverse order of removal.
LJIA0136E
1. Front heater and cooling unit assembly 2. Front blower motor 3. Variable blower control
LJIA0055E
1. Rear blower motor 2. Rear blower motor case 3. Rear blower motor resistor

ATC-142
IN-CABIN MICROFILTER
Revision: August 20072004 QX56
IN-CABIN MICROFILTERPFP:27277
Removal and InstallationEJS002D3
FUNCTION
The air inside the passenger compartment is filtered by the in-cabin
microfilters when the heater or A/C controls are set on either the
recirculation or fresh mode. The two in-cabin microfilters are located
in the front heater and cooling unit assembly. The rear heater and
cooling unit assembly only draws in air from the passenger compart-
ment to recirculate into the passenger compartment, so the rear
heater and cooling unit assembly is not equipped with in-cabin
microfilters.
REPLACEMENT TIMING
Replacement of the two in-cabin microfilters is recommended on a regular interval depending on the driving
conditions. Refer to MA-6, "
PERIODIC MAINTENANCE" . It may also be necessary to replace the two in-
cabin microfilters as part of a component replacement if the in-cabin microfilters are damaged.
REPLACEMENT PROCEDURE
1. Remove the two lower glove box hinge pins to remove the glove
box from the instrument panel and let it hang from the cord.
2. Remove the screw and remove the in-cabin microfilter cover.
3. Remove the in-cabin microfilters from the front heater and cool-
ing unit assembly housing.
4. Insert the first new in-cabin microfilter into the front heater and
cooling unit assembly housing and slide it over to the right.
Insert the second new in-cabin microfilter into the front heater
and cooling unit assembly housing.
NOTE:
The in-cabin microfilters are marked with air flow arrows. The
end of the microfilter with the arrow should face the rear of the
vehicle. The arrows should point downward.
LJIA0012E
WLIA0027E
LJIA0134E
LJIA0148E

ATC-144
HEATER & COOLING UNIT ASSEMBLY
Revision: August 20072004 QX56
HEATER & COOLING UNIT ASSEMBLYPFP:27110
ComponentsEJS002D4
Front Heater and Cooling Unit Assembly
WJIA0957E
1. High-pressure A/C pipe 2. Front expansion valve 3. Low-pressure A/C pipe
4. Front heater core pipe 5. Front heater core hose 6. A/C drain hose
7. Front heater and cooling unit assembly

HEATER & COOLING UNIT ASSEMBLY
ATC-145
C
D
E
F
G
H
I
K
L
MA
B
AT C
Revision: August 20072004 QX56
Rear A/C
Removal and InstallationEJS002D5
FRONT HEATER AND COOLING UNIT ASSEMBLY
Removal
1. Discharge the refrigerant from the A/C system. Refer to ATC-162, "Discharging Refrigerant" .
2. Drain the coolant from the engine cooling system. Refer to MA-12, "
DRAINING ENGINE COOLANT" .
3. Remove the cowl top extension. Refer to EI-18, "
Removal and Installation" .
WJIA2315E
1. Rear heater and cooling unit assembly 2. Rear A/C pipes 3. Rear A/C heater core pipes
4. Rear heater core hose 5. Rear blower motor 6. Underfloor rear A/C pipes
7. Underfloor rear heater core pipes A. Bolt torque specifications B. Leak checking order (l - r)
C. Tightening torque D. Wrench size E. O-ring size
⇐Front
NOTE: The O-ring size 8 is the high-side and the O-ring size 16 is the low-side.