2011 INFINITI QX56 cooling

HAC-10
< SYSTEM DESCRIPTION >[AUTOMATIC AIR CONDITIONING]
COMPONENT PARTS
REAR AUTOMATIC AIR CONDITIONING SYSTEM : Component Description
INFOID:0000000006275851
ACCS (ADVANCED CLIMATE CONTROL SYSTEM)
Component Description
Ambient sensor Ambient sensor measures ambient air temperature. The sensor uses a
thermistor which is sensitive to the change in temperature. The electrical
resistance of the thermistor decreases as temperature increases.
AV c o n t r o l u n i t AV control unit transmits front A/C control operation signal to A/C auto amp.
via CAN communication line.
A/C auto amp. A/C auto amp. controls rear automatic air conditioning system by inputting
and calculating signals from each sensor and each switch. A/C auto amp.
has self-diagnosis function. Diagnosis of rear automatic air conditioning
system can be performed quickly.
Combination meter Combination meter transmits vehicle speed signal to A/C auto amp. via
CAN communication line.
ECM ECM transmits engine coolant temperature signal to A/C auto amp. via
CAN communication line.
Engine coolant temperature sensor Engine coolant temperature sensor measures engine coolant temperature.
The sensor uses a thermistor which is sensitive to the change in tempera-
ture. The electrical resistance of the thermistor decreases as temperature
increases.
Front display Front display indicates operation status of rear automatic air conditioning
system.
Heater & cooling unit
assembly Intake sensor Intake sensor measures temperature of front evaporator fin temperature.
The sensor uses a thermistor which is sensitive to the change in tempera-
ture. The electrical resistance of the thermistor decreases as temperature
increases.
Preset switch Preset switch is integrated with front A/C control and AV operation switch.
Front A/C control operation signal is transmitted from preset switch to AV
control unit via communication line.
Rear A/C control The operation of the rear A/C control is communicated with the A/C auto
amp. via communication line.
Rear A/C relay Power is supplied to the rear A/C solenoid valve through rear A/C relay with
A/C auto amp. control.
Rear A/C unit assem-
bly Rear air mix door motor
The LCU (Local Contro
l Unit) is installed to rear air mix door motor so as to
perform the multiplex communication control (LIN).
Refer to HAC-26, "
REAR AUTOMATIC AIR CONDITIONING SYSTEM :
Door Control".
Rear A/C solenoid valve Rear A/C solenoid valve operates by power supply from rear A/C relay and
opens refrigerant line to rear evaporator.
Rear blower motor Refer to HAC-13
.
Rear in-vehicle sensor Rear in-vehicle sensor measures temperature of intake air that flows
through rear blower motor to passenger room. The sensor uses a ther-
mistor which is sensitive to the change in temperature. The electrical resis-
tance of the thermistor decreases as temperature increases.
Rear mode door motor The LCU (Local Control Unit) is installed to rear mode door motor so as to
perform the multiplex communication control (LIN).
Refer to
HAC-26, "
REAR AUTOMATIC AIR CONDITIONING SYSTEM :
Door Control".
Sunload sensor Sunload sensor measures sunload amount. This sensor is a dual system
so that sunload for driver side and passenger side are measured separate-
ly. This sensor converts sunload amount to voltage signal by photodiode
and transmits to A/C auto amp..
Revision: 2010 May2011 QX56

COMPONENT PARTSHAC-11
< SYSTEM DESCRIPTION > [AUTOMATIC AIR CONDITIONING]
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ACCS (ADVANCED CLIMATE CONTROL SYSTEM) : Component Parts Location
INFOID:0000000006275852
ACCS (ADVANCED CLIMATE CONTRO L SYSTEM) : Component Description
INFOID:0000000006275853
1. Preset switch 2. Exhaust gas / outside odor detecting
sensor3. AV control unit
Refer to AV- 9 , "
Component Parts Lo-
cation".
4. Front display 5. Ionizer 6. Intake door motor
7. A/C auto amp.
A. Left side of heater & cooling unit as- sembly B. Back side of blower unit assembly C. Cluster lid C is removed
JMIIA0814ZZ
Component Description
Blower unit Intake door motor The LCU (Local Control Unit) is installed to intake door motor so as to per-
form the multiplex communication control (LIN).
Refer to
HAC-18, "
FRONT AUTOMATIC AIR CONDITIONING SYSTEM :
Door Control".
AV c o n t r o l u n i t AV control unit transmits A/C switch operation signal to A/C auto amp. via
CAN communication line.
A/C auto amp. A/C auto amp. controls ACCS (advanced climate control system) by input-
ting and calculating signals from each sensor and each switch. A/C auto
amp. has self-diagnosis function. Diagnosis of ACCS (advanced climate
control system) can be performed quickly.
Exhaust gas / outside odor detecting sensor Exhaust gas / outside odor detecting sensor measures unpleasant odor out-
side of passenger room. In addition to previous exhaust gas detection func-
tion, unpleasant odor in ambient atmosphere is measured.
Revision: 2010 May2011 QX56

HAC-12
< SYSTEM DESCRIPTION >[AUTOMATIC AIR CONDITIONING]
COMPONENT PARTS
Aspirator
INFOID:0000000006275856
The aspirator generates the vacuum by the air blown from the heater
& cooling unit and draws the air of the passenger room to the front
in-vehicle sensor area via the aspirator duct.
Front Blower MotorINFOID:0000000006275857
The front blower motor utilizes a brush-less motor with a rotating
magnet. Quietness is improved comparing to a conventional motor
(brush motor) that rotates coil while brush functions as contact
points.
Front display Front display indicates operation status of ACCS (advanced climate control
system).
Heater & cooling unit as-
sembly Ionizer Ionizer generates an approximately equal proportional amount of positive
and negative ions in the air.
Preset switch Preset switch is integrated with front A/C control and AV operation switch.
Front A/C control operation signal is transmitted from preset switch to AV
control unit via communication line.
Component Description
RJIA1804E
RJIA2467J
ZHA152H
Revision: 2010 May2011 QX56

COMPONENT PARTSHAC-13
< SYSTEM DESCRIPTION > [AUTOMATIC AIR CONDITIONING]
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Rear Blower MotorINFOID:0000000006275858
The rear blower motor utilizes a brush-less motor with a rotating
magnet. Quietness is improved comp aring to a conventional motor
(brush motor) that rotates coil while brush functions as contact
points.
Refrigerant Pressure SensorINFOID:0000000006275859
Description
Refrigerant pressure sensor is installed to upper porti on of liquid tank. The refrigerant pressure sensor con-
verts high-pressure side refrigerant pressure into vo ltage and outputs it to ECM. ECM operates cooling system
protection and idle speed control according to voltage value that is input.
Structure and operation
The refrigerant pressure sensor is a capacitance type sensor. It consists of a pressure detection area and a
signal processing area. The pressure detection area, wh ich is a variable capacity condenser, changes internal
static capacitance according to pressure force. The signal processing area detects the static capacitance of
the pressure detection area, converts the static capacitance into a voltage value, and transmits the voltage
value to ECM.
RJIA2467J
ZHA152H
PBIB2657E
Revision: 2010 May2011 QX56

SYSTEMHAC-15
< SYSTEM DESCRIPTION > [AUTOMATIC AIR CONDITIONING]
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- HAC-17, "FRONT AUTOMATIC AIR CONDITIONING SYSTEM : Air Outlet Control"
-HAC-17, "FRONT AUTOMATIC AIR CONDITIONIN G SYSTEM : Compressor Control"
-HAC-18, "FRONT AUTOMATIC AIR CONDITION ING SYSTEM : Door Control"
-HAC-21, "FRONT AUTOMATIC AIR CONDITIONIN G SYSTEM : Temperature Control"
- Correction for input value of each sensor
Ambient sensor (setting temperature correction) A/C auto amp. controls passenger room temperature so that the optimum level always matches the temper-
ature level that passenger may feel. Correction is applied to the target temperature that is set using temper-
ature control dial, according to ambient temperature detected by ambient sensor.
Front in-vehicle sensor [in-vehicle temperature (front side) correction]
 Passenger room temperature (front side) detected by front in-vehicle sensor is corrected for each front air
conditioning control (driver side and passenger side)
Intake sensor (intake temperature correction)
 A/C auto amp. performs correction to change recognition intake temperature of A/C auto amp. quickly when
difference is large between recognition intake temperat ure and intake temperature detected by intake tem-
perature sensor. The correction is performed to change recognition intake temperature slowly when differ-
ence is small.
Sunload sensor (sunload amount correction) Sunload amount detected by sunload sensor is correc ted for each air conditioning control (driver side and
passenger side).
 A/C auto amp. performs correction to change recogni tion sunload amount of A/C auto amp. slowly when
sunload amount changes quickly, for exampl e when entering or exiting a tunnel.
Control by ECM
- Cooling fan control
Refer to EC-41, "
COOLING FAN CONTROL : System Description".
- Air conditioning cut control.
Refer to EC-47, "
AIR CONDITIONING CUT CONTRO L : System Description".
Control by IPDM E/R- Relay control
Refer to PCS-5, "
RELAY CONTROL SYSTEM : System Description".
- Cooling fan control
Refer to PCS-8, "
POWER CONTROL SYSTEM : System Description".
 Front A/C control (preset switch) transmits the co mmands for front automatic air conditioning system opera-
tion to AV control unit via communication line, then AV control unit transmits the commands to A/C auto amp.
via CAN communication. A/C auto amp. transmits each indication information to AV control unit via CAN
communication. AV control unit displays each indication information that is received.
FRONT AUTOMATIC AIR CONDITIONIN G SYSTEM : Air Flow ControlINFOID:0000000006275862
DESCRIPTION
 A/C auto amp. changes duty ratio of blower motor dr ive signal and controls air flow continuously. When air
flow is increased, duty ratio of front blower moto r control signal gradually increases to prevent a sudden
increase in air flow.
 In addition to manual control and automatic control, air flow control is consist of starting fan speed control,
low coolant temperature starting control, high in-vehi cle temperature starting control and fan speed control at
door motor operation
AUTOMATIC AIR FLOW CONTROL
 A/C auto amp. decides target air flow depending on target front air mix door opening angle.
 A/C auto amp. changes duty ratio of front blower moto r control signal and controls the air flow continuously
so that air flow matches to target air flow.
Revision: 2010 May2011 QX56

HAC-134
< SYMPTOM DIAGNOSIS >[AUTOMATIC AIR CONDITIONING]
FRONT AUTOMATIC AIR CONDITIONING SYSTEM
Compressor does not operate. Circuit between magnet clutch and
IPDM E/R
 Magnet clutch
 IPDM E/R (A/C relay)
 Circuit between ECM and refriger- ant pressure sensor
 Refrigerant pressure sensor
 CAN communication circuit
 A/C auto amp. HAC-142, "Diagnosis Procedure"
 Insufficient cooling.
 No cool air comes out. (Air flow volume is normal.)
 Magnet clutch control system
 Drive belt slipping
 Refrigerant cycle
 Air leakage from each duct
 A/C auto amp. connection recogni-
tion signal circuit
 Temperature settin g trimmer (front)HAC-138, "FRONT AIR CONDI-
TIONER : Diagnosis Procedure"
 Insufficient heating.
 No warm air comes out. (Air flow volume is nor-
mal.)  Engine cooling system
 Heater hose
 Heater core
 Air leakage from each duct
 Temperature settin
g trimmer (front)HAC-140, "FRONT AIR CONDI-
TIONER : Diagnosis Procedure"
Noise is heard when front
air conditioning system op-
erates. During compressor
operation
Refrigerant cycle
HA-27, "
Symptom Table"
During front blower
motor operation Mixing any foreign object in front
blower motor
 Front blower motor fan breakage
 Front blower motor rotation inferiori- ty HAC-122, "Component Inspection
(Front Blower Motor)"
 Memory function does not operate.
 Setting temperature is not memorized.
 Battery power supply system of A/C
auto amp.
 A/C auto amp. HAC-110, "A/C AUTO AMP. : Diag-
nosis Procedure"
Symptom Corresponding malfunction part Reference
Revision: 2010 May2011 QX56

REAR AUTOMATIC AIR CONDITIONING SYSTEMHAC-135
< SYMPTOM DIAGNOSIS > [AUTOMATIC AIR CONDITIONING]
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REAR AUTOMATIC AIR CONDITIONING SYSTEM
Diagnosis Chart By SymptomINFOID:0000000006275981
NOTE:
 Perform the self-diagnoses with CONSULT-III before performing the symptom diagnosis. If DTC is detected,
perform the corresponding diagnosis.
 The following table is based on the condition that fr ont automatic air conditioning system operates normally.
Symptom Corresponding malfunction part Reference
 Rear air conditioning system cannot be controlled. (Front A/C control)
 Operation status of rear air conditioning system is not indicated on front display. Multi AV system
AV- 1 9 9 , "
Symptom Table"
Rear air conditioning sys-
tem cannot be controlled.
(Rear A/C control)Operation status of
rear air conditioning
system is not indicated
on rear A/C control
display
 Power supply system of rear A/C
control
 Rear A/C control HAC-115, "
REAR A/C CONTROL :
Diagnosis Procedure"
Operation status of
rear air conditioning
system is indicated on
rear A/C control dis-
play Communication circuit between rear
A/C control and A/C auto amp.
 A/C auto amp. HAC-127, "
Diagnosis Procedure"
 Air outlet does not change.
 Rear mode door motor does not operate normally.  Circuit between rear mode door mo-
tor and A/C auto amp.
 Rear mode door motor control link- age
 Front mode door motor
 A/C auto amp. HAC-116, "REAR MODE DOOR
MOTOR : Diagnosis Procedure"
 Discharge air temperature does not change.
 Rear air mix door motor does not operate normally.  Circuit between rear air mix door
motor and A/C auto amp.
 Rear air mix door motor installation condition
 Rear air mix door motor
 A/C auto amp. HAC-114, "REAR AIR MIX DOOR
MOTOR : Diagnosis Procedure"
Rear blower motor operation is malfunctioning.
 Power supply system of rear blower
motor
 Circuit between rear blower motor
and A/C auto amp..
 Rear blower motor
 A/C auto amp. HAC-131, "Diagnosis Procedure"
 Insufficient cooling.
 No cool air comes out. (Air flow volume is normal.)  Power supply system of rear A/C re-
lay
 Circuit between rear A/C relay and A/C auto amp..
 Circuit between rear A/C relay and rear A/C solenoid valve.
 Circuit between rear A/C solenoid
valve and ground.
 Rear A/C relay
 Rear A/C solenoid valve
 A/C auto amp.
 Refrigerant cycle
 Air leakage from each duct
 Temperature setti ng trimmer (rear) HAC-139, "REAR AIR CONDI-
TIONER : Diagnosis Procedure"
Revision: 2010 May2011 QX56

HAC-136
< SYMPTOM DIAGNOSIS >[AUTOMATIC AIR CONDITIONING]
REAR AUTOMATIC AIR CONDITIONING SYSTEM
 Insufficient heating.
 No warm air comes out. (Air flow volume is nor-
mal.)  Engine cooling system
 Heater hose
 Rear heater core
 Air leakage from each duct
 Temperature setting trimmer (rear)
HAC-141, "REAR AIR CONDI-
TIONER : Diagnosis Procedure"
Noise is heard when rear blower motor operates.
 Mixing any foreign object in rear
blower motor
 Rear blower motor fan breakage
 Rear blower motor rotation inferiori- ty HAC-132, "Component Inspection"
Symptom Corresponding malfunction part Reference
Revision: 2010 May2011 QX56