2011 INFINITI QX56 engine

HAC-16
< SYSTEM DESCRIPTION >[AUTOMATIC AIR CONDITIONING]
SYSTEM
 When air outlet is VENT or B/L, the minimum air flow is changed
depending on sunload.
STARTING AIR FLOW CONTROL
 When front blower motor is activated, A/C auto amp. graduallyincreases duty ratio of front blower motor control signal to prevent
a sudden increase in discharge air flow.
 It takes approximately 8 seconds for air flow to reach HI from LOW.
LOW COOLANT TEMPERATURE STARTING CONTROL
If the engine coolant temperature is 56 °C (133 °F) or less, to prevent
a cold discharged air flow, A/C auto amp. suspends front blower
motor activation for the maximum 150 seconds depending on target
front air mix door opening angle. After this, front blower motor control
signal is increased gradually, and front blower motor is activated.
HIGH IN-VEHICLE TEMPERATURE STARTING CONTROL
When front evaporator fin temperature is high [intake sensor value is 35°C (95 °F) or more], to prevent a hot
discharged air flow, A/C auto amp. suspends front blower motor activation for approximately 3 seconds so that
front evaporator is cooled by refrigerant.
FAN SPEED CONTROL AT DOOR MOTOR OPERATION
When front mode door motor is activated while air flow is more than the specified value, A/C auto amp.
reduces temporarily fan speed wo that front mode door moves smoothly.
FRONT AUTOMATIC AIR CONDITIONIN G SYSTEM : Air Inlet ControlINFOID:0000000006275863
The intake door is automatically controlled by the temperature set-
ting, ambient temperature, in-vehicle temperature (front side), intake
temperature, amount of sunload and ON/OFF operation of the com-
pressor.
Intake door automatic control selects FRE, 20% FRE, or REC
depending on a target front air mix door opening angle, based on in-
vehicle temperature (front side) , ambient temperature, and sunload.
JMIIA0735GB
JMIIA0736GB
JMIIA0737GB
JMIIA0732GB
Revision: 2010 May2011 QX56

SYSTEMHAC-17
< SYSTEM DESCRIPTION > [AUTOMATIC AIR CONDITIONING]
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FRONT AUTOMATIC AIR CONDITIONIN G SYSTEM : Air Outlet ControlINFOID:0000000006275864
 While air outlet is in automatic control, A/C auto amp. selects the
front mode door position depending on a target front air mix door
angle and outlet air temperature calculated from sunload.
 If ambient temperature is excessively low, D/F is selected to pre- vent windshield fogging when air outlet is set to FOOT.
FRONT AUTOMATIC AIR CONDITIONIN G SYSTEM : Compressor Control
INFOID:0000000006275865
DESCRIPTION
 When the compressor activation condition is satisfied while blower motor is activated, A/C auto amp. trans-
mits A/C ON signal and blower fan ON signal to ECM via CAN communication.
 ECM judges that the compressor can be activated depending on each sensors state (refrigerant pressure sensor signal, and others). And transmits A/C compress or request signal to IPDM E/R via CAN communica-
tion.
 IPDM E/R turns A/C relay ON and activates the compressor depending on request from ECM.
COMPRESSOR PROTECTION CONTROL AT PRESSURE MALFUNCTION
When high-pressure side value that is detected by refri gerant pressure sensor is as per the following state,
ECM requests IPDM E/R to turn A/C relay OFF and stops the compressor.
 3.12 MPa (31.82 kg/cm
2, 452.4 psi) or more (When the engine speed is less than 1,500 rpm)
 2.74 MPa (27.95 kg/cm
2, 397.3 psi) or more (When the engine speed is 1,500 rpm or more)
 0.14 MPa (1.43 kg/cm
2, 20.3 psi) or less
COMPRESSOR OIL CIRCULATION CONTROL
When the engine starts while the engine coolant temperature is 56 °C (133 °F) or less, ECM activates the com-
pressor for approximately 6 seconds and circulates the compressor lubricant once.
LOW TEMPERATURE PROTECTION CONTROL
 When intake sensor detects that front evaporator fin temperature is
2.5 °C (37 °F) or less, A/C auto amp. requests ECM to turn com-
pressor OFF, and stops the compressor.
 When the front evaporator fin temperature returns to 5.0 °C (41 °F)
or more, the compressor is activated.
OPERATING RATE CONTROL
When set temperature is other than fully cold or air out let is “VENT”, “B/L” or “FOOT” A/C auto amp. controls
the compressor activation depending on ambient temperature.
AIR CONDITIONING CUT CONTROL
When set engine is running is excessively high load conditi on, ECM requests IPDM E/R to turn A/C relay OFF,
and stops the compressor. Refer to EC-47, "
AIR CONDITIONING CUT CONTRO L : System Description" for
details.
JMIIA0730GB
JMIIA0742GB
Revision: 2010 May2011 QX56

HAC-22
< SYSTEM DESCRIPTION >[AUTOMATIC AIR CONDITIONING]
SYSTEM
If a communication error exists between the A/C auto
amp., and the AV control unit and preset switch for 30
seconds or longer, air conditioning is controlled under the following conditions:
When ambient temperature is less than 3 °C (37 °F) and engine coolant tem perature is less than 56°C (133 °F)
When ambient temperature is 3 °C (37 °F) or more, or engine coolant temperature is 56 °C (133 °F) or more
REAR AUTOMATIC AIR CONDITIONING SYSTEM
Compressor : ON
Air outlet : DEF
Air inlet : FRE (Fresh air intake)
Blower fan speed : AUTO
Set temperature : Setting before communication error occurs
Compressor : ON
Air outlet : AUTO
Air inlet : 20% FRE (20% fresh air intake)
Blower fan speed : AUTO
Set temperature : Setting before communication error occurs
Revision: 2010 May2011 QX56

SYSTEMHAC-25
< SYSTEM DESCRIPTION > [AUTOMATIC AIR CONDITIONING]
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 When rear blower motor is activated, A/C auto amp. gradually increases duty ratio of rear blower motor control signal to prevent a
sudden increase in discharge air flow.
 It takes approximately 8 seconds for air flow to reach HI from LOW.
LOW COOLANT TEMPERATURE STARTING CONTROL
If the engine coolant temperature is 56 °C (133 °F) or less, to prevent
a cold discharged air flow, A/C auto amp. suspends rear blower
motor activation for the maximum 150 seconds depending on target
rear air mix door opening angle. After this, rear blower motor control
signal is increased gradually, and rear blower motor is activated.
HIGH IN-VEHICLE TEMPERATURE STARTING CONTROL
When front evaporator fin temperature is high [intake sensor value is 35°C (95 °F) or more], to prevent a hot
discharged air flow, A/C auto amp. suspends rear blower motor activation for approximately 3 seconds so that
rear evaporator is cooled by refrigerant.
FAN SPEED CONTROL AT DOOR MOTOR OPERATION
When rear mode door motor is activated while air flow is more than the specified value, A/C auto amp.
reduces temporarily fan speed wo t hat rear mode door moves smoothly.
REAR AUTOMATIC AIR CONDITIONING SYSTEM : Air Outlet ControlINFOID:0000000006275872
 While air outlet is in automatic control, A/C auto amp. selects the
rear mode door position depending on a target rear air mix door
angle and outlet air temperature calculated from sunload.
JMIIA0739GB
JMIIA0740GB
JMIIA0733GB
Revision: 2010 May2011 QX56

DIAGNOSIS SYSTEM (HVAC)HAC-39
< SYSTEM DESCRIPTION > [AUTOMATIC AIR CONDITIONING]
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DIAGNOSIS SYSTEM (HVAC)
DescriptionINFOID:0000000006275884
Air conditioning system performs self-diagnosis, operat ion check, function diagnosis, and various settings
using diagnosis function of each control unit.
CONSULT-III FunctionINFOID:0000000006275885
CONSULT-III performs the following functions via CAN communication with A/C auto amp.
NOTE:
Diagnosis should be performed with engine running. D oor motor operation speeds become slower and NO
results may be returned even for normal operation if battery voltage drops below 12 V during self-diagnosis.
SELF-DIAGNOSIS RESULTS
Refer to HAC-45, "DTC Index".
DATA MONITOR
Display item list
ECU Diagnostic item
(CONSULT-III)
A/C auto amp. HVACSelf Diagnostic Result
Data Monitor
Active Test
Work support
AV c o n t r o l u n i t MULTI AV
Self Diagnostic Result
Multi AV system on board diagnosis function
ECM ENGINESelf Diagnostic Result
Data Monitor
IPDM E/R IPDM E/RSelf Diagnostic Result
Data Monitor
Auto active test
Diagnostic mode Description
Self diagnostic result Displays the diagnosis results judged by A/C auto amp.
Data monitor Displays the input/output signal of A/C auto amp.
Active test The signals used to activate each device are forcibly supplied from A/C auto amp.
Work support Changes the setting for each setting function.
ECU identification Displays the part number of A/C auto amp.
Monitor item [Unit] Description
AMB TEMP SEN [ °C ( °F)] Ambient sensor value converted from ambient sensor signal received from ambient sen-
sor
IN-VEH TEMP [ °C ( °F)] Front in-vehicle sensor value converted from front in-vehicle sensor signal received from
front in-vehicle sensor
INT TEMP SEN [ °C ( °F)] Intake sensor value converted from intake sensor signal received from intake sensor
SUNLOAD SEN [w/m
2]Sunload sensor value converted from sunload sensor signal (driver side) received from
sunload sensor
AMB SEN CAL [ °C ( °F)] Ambient temperature value calculated by A/C auto amp.
IN-VEH CAL [ °C ( °F)] In-vehicle temperature (front side) value calculated by A/C auto amp.
INT TEMP CAL [ °C ( °F)] Front evaporator fin temperature value calculated by A/C auto amp.
SUNL SEN CAL [w/m
2]Sunload value (driver side) calculated by A/C auto amp.
Revision: 2010 May2011 QX56

HAC-40
< SYSTEM DESCRIPTION >[AUTOMATIC AIR CONDITIONING]
DIAGNOSIS SYSTEM (HVAC)
ACTIVE TEST
Check each output device
COMP REQ SIG [On/Off] Displays A/C switch ON/OFF status transmitted to other units via CAN communication
FAN REQ SIG [On/Off]Displays front blower motor ON/OFF status transmitted to other units via CAN commu-
nication
FAN DUTY Duty ratio of front blower motor judged by A/C auto amp.
XM Target discharge front air temperature (driver side) judged by A/C auto amp. depending
on the temperature setting and the value from each sensor
PASS SUNL CAL [w/m
2]Sunload value (passenger side) calculated by A/C auto amp.
PASS SUNLOAD SEN [w/m
2]Sunload sensor value converted from sunload sensor signal (passenger side) received
from sunload sensor
PA TARGET A/TEMP Target discharge front air temperature (passenger side) judged by A/C auto amp. de-
pending on the temperature setting and the value from each sensor
RRIN TEMP SEN [ °C ( °F)] Rear in-vehicle sensor value converted from rear in-vehicle sensor signal received from
rear in-vehicle sensor.
RRIN TEMP CAL [ °C ( °F)] In-vehicle temperature (rear side) value calculated by A/C auto amp.
RR INT TMP CL [ °C ( °F)] Rear evaporator fin temperature value calculated by A/C auto amp.
RRFAN REQ SIG [On/Off] Displays rear blower motor ON/OFF status transmitted to other units via CAN communi-
cation
RR FAN DUTY Duty ratio of rear blower motor judged by A/C auto amp.
RR XM Target discharge rear air temperature (driver side) judged by A/C auto amp. depending
on the temperature setting and the value from each sensor
ENG COOL TEMP [ °C ( °F)] Engine coolant temperature signal value received from ECM via CAN communication
VEHICLE SPEED [km/h
(mph)] Vehicle speed signal value received from combination meter via CAN communication
Monitor item [Unit] Description
Te s t i t e m D e s c r i p t i o n
HVAC TEST The operation check of air conditioning system can be performed by selecting the mode.
Refer to the following table for the conditions of each mode.
Te s t i t e m
MODE 1 MODE 2 MODE 3 MODE 4 MODE 5 MODE 6 MODE 7
Front mode door motor posi-
tion VENT VENT B/L B/L FOOT D/F DEF
Intake door motor position REC REC 20% FRE 20% FRE FRE FRE FRE
Front air mix door motor (driver
side) position FULL COLD FULL COLD FULL COLD FULL HOT FULL HOT FULL HOT FULL HOT
Front air mix door motor (pas-
senger side) position FULL COLD FULL COLD FULL COLD FULL HOT FULL HOT FULL HOT FULL HOT
Front blower motor control sig-
nal duty ratio 35% 35% 59% 59% 89% 89% 35%
Magnet clutch ON ON ON ON OFF OFF ON
Upper ventilator door motor
position OPEN CLOSE OPEN CLOSE CLOSE CLOSE CLOSE
Rear mode door motor posi-
tion VENT VENT B/L B/L FOOT FOOT FOOT
Rear air mix door motor posi-
tion FULL COLD FULL COLD FULL COLD FULL HOT FULL HOT FULL HOT FULL HOT
Rear blower motor control sig-
nal duty ratio 35% 35% 59% 59% 89% 89% 35%
Revision: 2010 May2011 QX56

DIAGNOSIS SYSTEM (HVAC)HAC-41
< SYSTEM DESCRIPTION > [AUTOMATIC AIR CONDITIONING]
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*: With ACCS (advanced climate control system)
NOTE:
Perform the inspection of each output device after starting the engine because the compressor is operated.
WORK SUPPORT
*: With ACCS (advanced climate control system)
NOTE:
When the battery cable is disconnected from the negative terminal or when the battery voltage becomes 10 V
or less, the setting of WORK SUPPORT may be cancelled.
Rear A/C relay ON ON ON ON OFF OFF ON
Ionizer
*ON ON ON ON ON ON OFF
Front display (Ion mode)
*CLEAN CLEAN QUICK
CLEAN QUICK
CLEAN QUICK
CLEAN QUICK
CLEAN OFF
Te s t i t e m
MODE 1 MODE 2 MODE 3 MODE 4 MODE 5 MODE 6 MODE 7
Work item Description Refer to
TEMP SET CORRECT Setting change of temperature setting trimmer (front) can be per-
formed. HAC-68, "
FRONT AUTO-
MATIC AIR CONDITION-
ING SYSTEM :
Temperature Setting Trim-
mer (Front)"
BLOWER SET Setting change of foot position setting trimmer can be performed.
HAC-68, "
FRONT AUTO-
MATIC AIR CONDITION-
ING SYSTEM : Foot
Position Setting Trimmer"
REC MEMORY SET
Setting change of inlet port memory function (REC) can be per-
formed. HAC-69, "
FRONT AUTO-
MATIC AIR CONDITION-
ING SYSTEM : Inlet Port
Memory Function (REC)"
FRE MEMORY SET
Setting change of inlet port memory function (FRE) can be per-
formed. HAC-69, "
FRONT AUTO-
MATIC AIR CONDITION-
ING SYSTEM : Inlet Port
Memory Function (FRE)"
GAS SENSOR ADJUSTMENT*Setting change of exhaust gas / outside odor detecting sensor sensi-
tivity adjustment function can be performed. HAC-70, "
ACCS (AD-
VANCED CLIMATE CON-
TROL SYSTEM) :
Exhaust Gas / Outside
Odor Detecting Sensor
Sensitivity Adjustment
Function"
CLEAN SW SET*Setting change of auto intake switch interlocking movement change
function can be performed.
HAC-70, "
ACCS (AD-
VANCED CLIMATE CON-
TROL SYSTEM) : Auto
Intake Switch Interlocking
Movement Change Func-
tion"
REAR TEMP SET CORRECT
Setting change of temperature setting trimmer (rear) can be per-
formed. HAC-68, "
FRONT AUTO-
MATIC AIR CONDITION-
ING SYSTEM :
Temperature Setting Trim-
mer (Front)"
Revision: 2010 May2011 QX56

HAC-42
< ECU DIAGNOSIS INFORMATION >[AUTOMATIC AIR CONDITIONING]
A/C AUTO AMP.
ECU DIAGNOSIS INFORMATION
A/C AUTO AMP.
Reference ValueINFOID:0000000006275886
CONSULT-III DATA MONITOR REFERENCE VALUES
Monitor item Condition Value/Status
AMB TEMP SEN Ignition switch ON — Equivalent to ambient tem-
perature
IN-VEH TEMP Ignition switch ON — Equivalent to in-vehicle tem-
perature (front side)
INT TEMP SEN Ignition switch ON — Equivalent to front evapora-
tor fin temperature
SUNLOAD SEN Ignition switch ON — Equivalent to sunload (driver
side)
AMB SEN CAL Ignition switch ON — Equivalent to ambient tem-
perature
IN-VEH CAL Ignition switch ON — Equivalent to in-vehicle tem-
perature (front side)
INT TEMP CAL Ignition switch ON — Equivalent to front evapora-
tor fin temperature
SUNL SEN CAL Ignition switch ON — Equivalent to sunload (driver
side)
COMP REQ SIG Engine: Run at idle after
warming up A/C switch: ON
(Compressor operation sta-
tus)
On
A/C switch: OFF Off
FAN REQ SIG Engine: Run at idle after
warming up Front blower motor: ON On
Front blower motor: OFF Off
FAN DUTY Engine: Run at idle after
warming up Front blower motor: ON 25 – 81
Front blower motor: OFF 0
XM Ignition switch ON — Value according to target air
flow temperature (driver
side)
PASS SUNL CAL Ignition switch ON — Equivalent to sunload (pas-
senger side)
PASS SUNLOAD SEN Ignition switch ON — Equivalent to sunload (pas-
senger side)
PA TARGET A/TEMP Ignition switch ON — Value according to target air
flow temperature (passen-
ger side)
RRIN TEMP SEN Ignition switch ON — Equivalent to in-vehicle tem-
perature (rear side)
RRIN TEMP CAL Ignition switch ON — Equivalent to in-vehicle tem-
perature (rear side)
RR INT TMP CL Ignition switch ON — Equivalent to rear evapora-
tor fin temperature
RRFAN REQ SIG Engine: Run at idle after
warming up Rear blower motor: ON On
Rear blower motor: OFF Off
RR FAN DUTY Engine: Run at idle after
warming up Rear blower motor: ON 25 – 81
Rear blower motor: OFF 0
Revision: 2010 May2011 QX56