2011 INFINITI QX56 coolant

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

HAC-24
< SYSTEM DESCRIPTION >[AUTOMATIC AIR CONDITIONING]
SYSTEM
 A/C auto amp. controls passenger r
oom 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.
Rear in-vehicle sensor [in-vehicle temperature (rear side) correction]
 Passenger room temperature (rear side) detected by r ear in-vehicle sensor is corrected for each rear auto-
matic air conditioning control.
Intake sensor (intake temperature correction)
 A/C auto amp. performs correction to change recogniti on 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 correct ed for each rear automatic air conditioning control.
 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.
 Front control
Operation by front controller
- Front A/C control (preset switch) transmits the co mmands for rear 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.
Operation by rear controller- Rear A/C control transmits the commands for rear automatic air conditioning system operation to A/C auto
amp. via communication line.
REAR AUTOMATIC AIR CONDITIONIN G SYSTEM : Air Flow ControlINFOID:0000000006275871
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 rear 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 compose 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 rear air mix door opening angle.
 A/C auto amp. changes duty ratio of rear blower moto r control signal and controls the air flow continuously
so that air flow matches to target air flow.
 When air outlet is VENT or B/L, the minimum air flow is changed depending on sunload.
STARTING AIR FLOW CONTROL
JMIIA0738GB
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

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

A/C AUTO AMP.HAC-43
< ECU DIAGNOSIS INFORMATION > [AUTOMATIC AIR CONDITIONING]
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TERMINAL LAYOUT
PHYSICAL VALUES
RR XM Ignition switch ON — Value according to target air
flow temperature (rear side)
ENG COOL TEMP Ignition switch ON — Equivalent to engine coolant
temperature
VEHICLE SPEED Driving — Equivalent to speedometer
reading
Monitor item Condition Value/Status
JMIIA0787ZZ
Te r m i n a l N o .
(Wire color) Description
ConditionVa l u e
(Approx.)
+ − Signal name Input/
Output
1
(L) —CAN-H Input/
Output ——
2
(B) —Ground — — —
3
(Y/G) Ground Battery power supply Input Ignition switch OFF Battery voltage
4
(V) Ground ACC power supply Input Ignition switch ACC Battery voltage
5
*1
(W) Ground
Ionizer (ON/OFF) control
signal
OutputIgnition
switch
ON Front blower
motor: ON
0 V
Front blower
motor: OFF 12 V
6
(V/W) GroundA/C auto amp. connection
recognition signal Output Ignition switch ON 12 V
7
(W/R) Ground Ambient sensor signal Input Ignition switch ON 0 – 4.8 V
Output voltage varies with ambient temperature
8
(GR/L) Ground
Rear in-vehicle sensor sig-
nal Input Ignition switch ON 0 – 4.8 V
Output voltage varies with in-vehi-
cle temperature (rear side)
9
(BR) GroundSunload sensor (driver side)
signal
Input Ignition switch ON 0 – 4.8 V
Output voltage varies with sunload (driver side) amount
10
*1
(V/W) Ground
Exhaust gas / outside odor
detecting sensor signal InputIgnition switch ON
NOTE:
The signal is depending
on measurement environ-
ment of the vehicle
ZJIA1163J
Revision: 2010 May2011 QX56

A/C AUTO AMP.HAC-45
< ECU DIAGNOSIS INFORMATION > [AUTOMATIC AIR CONDITIONING]
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*1: With ACCS (advanced climate control system)
*2: A/C auto amp. is not used for control.
Fail-safeINFOID:0000000006275887
FAIL-SAFE FUNCTION
If a communication error exists between the A/C auto am p., 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 temperature 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
DTC IndexINFOID:0000000006275888
34
(L/O) GroundRear blower motor control
signal Output Ignition switch ON
 Rear fan speed: 1st
speed (manual)
37
(B) —Ground — — —
38
(G/W) Ground Rear A/C relay control signal Output Ignition
switch
ONRear blower
motor: ON
0 V
Rear blower
motor: OFF 12 V
Te r m i n a l N o .
(Wire color) Description
ConditionVa l u e
(Approx.)
+ − Signal name Input/
Output
JSIIA0096ZZ
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
DTC Items
(CONSULT-III screen terms) Reference
U1000 CAN COMM CIRCUIT HAC-72, "
DTC Logic"
U1010 CONTROL UNIT (CAN)HAC-73, "DTC Logic"
B2578 IN-VEHICLE SENSORHAC-74, "DTC Logic"
B2579 IN-VEHICLE SENSORHAC-74, "DTC Logic"
B257B AMBIENT SENOR HAC-77, "DTC Logic"
B257C AMBIENT SENOR HAC-77, "DTC Logic"
B2581 INTAKE SENSORHAC-80, "DTC Logic"
B2582 INTAKE SENSORHAC-80, "DTC Logic"
Revision: 2010 May2011 QX56