Content .. 779 780 781 782 ..

Infiniti QX56 (Z62). Manual - part 781

SYSTEM

HAC-15

< SYSTEM DESCRIPTION >

[AUTOMATIC AIR CONDITIONING]

HAC

HAC-17, "FRONT AUTOMATIC AIR CONDITIONING SYSTEM : Air Outlet Control"

HAC-17, "FRONT AUTOMATIC AIR CONDITIONING SYSTEM : Compressor Control"

HAC-18, "FRONT AUTOMATIC AIR CONDITIONING SYSTEM : Door Control"

HAC-21, "FRONT AUTOMATIC AIR CONDITIONING 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 temperature 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 corrected for each air conditioning control (driver side and

passenger side).

• A/C auto amp. performs correction to change recognition sunload amount of A/C auto amp. slowly when

sunload amount changes quickly, for example 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 CONTROL : 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 commands 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 CONDITIONING SYSTEM : Air Flow Control

INFOID:0000000006275862

DESCRIPTION

• A/C auto amp. changes duty ratio of blower motor drive signal and controls air flow continuously. When air

flow is increased, duty ratio of front blower motor 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-vehicle 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 motor control signal and controls the air flow continuously

so that air flow matches to target air flow.

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. gradually

increases 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 CONDITIONING SYSTEM : Air Inlet Control

INFOID: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

SYSTEM

HAC-17

< SYSTEM DESCRIPTION >

[AUTOMATIC AIR CONDITIONING]

HAC

FRONT AUTOMATIC AIR CONDITIONING SYSTEM : Air Outlet Control

INFOID: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 CONDITIONING 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 compressor 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 refrigerant 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

, 452.4 psi) or more (When the engine speed is less than 1,500 rpm)

• 2.74 MPa (27.95 kg/cm

, 397.3 psi) or more (When the engine speed is 1,500 rpm or more)

• 0.14 MPa (1.43 kg/cm

, 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

or more, the compressor is activated.

OPERATING RATE CONTROL

When set temperature is other than fully cold or air outlet 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 condition, ECM requests IPDM E/R to turn A/C relay OFF,
and stops the compressor. Refer to

EC-47, "AIR CONDITIONING CUT CONTROL : System Description"

for

details.

JMIIA0730GB

JMIIA0742GB

HAC-18

< SYSTEM DESCRIPTION >

[AUTOMATIC AIR CONDITIONING]

SYSTEM

FRONT AUTOMATIC AIR CONDITIONING SYSTEM : Door Control

INFOID:0000000006275866

DOOR MOTOR CONTROL

• LCU (Local Control Unit) is built in to each door motor. And detects door position by PBR (Potentio Balance

Resistor).

• A/C auto amp. communicates with each LCU via communication line. And receives each door position feed

back signal from each LCU.

• Each LCU controls each door to the appropriate position depending on the control signal from A/C auto amp.

when the door movement is complete, transmits the signal of door movement completion to A/C auto amp.

SWITCHES AND THEIR CONTROL FUNCTION

With ACCS (Advanced Climate Control System)

JMIIA0817GB

JMIIA0727ZZ

Content .. 779 780 781 782 ..