2004 INFINITI QX56 cooling

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.

ATC-146
HEATER & COOLING UNIT ASSEMBLY
Revision: August 20072004 QX56
4. Remove the exhaust system. Refer to EX-3, "Removal and Installation" .
5. Disconnect the front heater hoses from the front heater core.
6. Disconnect the high/low pressure pipes from the front expansion valve.
7. Move the two front seats to the rearmost position on the seat track.
8. Remove the instrument panel and console panel. Refer to IP-10, "
INSTRUMENT PANEL ASSEMBLY" .
9. Remove the steering column. Refer to PS-10, "
Removal and Installation" .
10. Disconnect the instrument panel wire harness at the RH and LH in-line connector brackets, and the fuse
block (J/B) electrical connectors. Refer to PG-40, "
Harness Layout" .
11. Disconnect the steering member from each side of the vehicle body.
12. Remove the front heater and cooling unit assembly with it attached to the steering member, from the vehi-
cle.
CAUTION:
Use care not to damage the seats and interior trim panels when removing the front heater and
cooling unit assembly with it attached to the steering member.
13. Remove the front heater and cooling unit assembly from the steering member.
Installation
Installation is in the reverse order of removal.
CAUTION:

Replace the O-ring of the low-pressure pipe and high-pressure pipe with a new one, and apply
compressor oil to it when installing it.

After charging the refrigerant, check for leaks.
NOTE:

Fill the engine cooling system with the specified coolant mixture. Refer to MA-13, "REFILLING ENGINE
COOLANT" .

Recharge the A/C system. Refer to ATC-162, "Evacuating System and Charging Refrigerant" .
REAR 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. Disconnect the rear heater core hoses from the rear heater core.
4. Disconnect the rear A/C pipes from the rear expansion valve.
5. Remove the rear RH interior trim panel. Refer to EI-34,
"Removal and Installation" .
6. Disconnect the following electrical connectors:

Rear blower motor

Rear blower motor resistor

Rear air mix door motor
7. Disconnect the ducts from the rear heater and cooling unit
assembly.
8. Remove the rear heater and cooling unit assembly.
Installation
Installation is in the reverse order of removal.
CAUTION:

Replace the O-ring of the low-pressure pipe and high-pressure pipe with a new one, and apply
compressor oil to it when installing it.

After charging the refrigerant, check for leaks.
NOTE:

Fill the engine cooling system with the specified coolant mixture. Refer to MA-13, "REFILLING ENGINE
COOLANT" .

Recharge the A/C system. Refer to ATC-162, "Evacuating System and Charging Refrigerant" .
LJIA0021E

HEATER CORE
ATC-147
C
D
E
F
G
H
I
K
L
MA
B
AT C
Revision: August 20072004 QX56
HEATER COREPFP:27140
ComponentsEJS002D6
Front Heater and Cooling Unit Assembly
LJIA0138E
1. Heater core cover 2. Heater core pipe bracket 3. Heater core
4. Upper bracket 5. Upper heater and cooling unit case 6. A/C evaporator
7. Lower heater and cooling unit case 8. Blower motor 9. Variable blower control