Nissan Quest E52. Manual - part 722

HAC-18

< SYSTEM DESCRIPTION >

[AUTOMATIC AIR CONDITIONING]

SYSTEM

FRONT AUTOMATIC AIR CONDITIONING SYSTEM : Air Outlet Control

INFOID:0000000009652512

• 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 : Air Flow Control

INFOID:0000000009652513

DESCRIPTION

• A/C auto amp. changes duty ratio of front blower motor control signal to control 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 compose of starting air flow 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 to control 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

When front blower motor is activated, A/C auto amp. gradually increases duty ratio of blower motor control sig-
nal to prevent a sudden increase in discharge air flow. It takes approximately 8 seconds for air flow to reach HI
from LOW.
NOTE:
Do not perform the starting air flow control when the discharge outlet
is set to DEF.

LOW COOLANT TEMPERATURE STARTING CONTROL

JMIIA0730GB

JMIIA0735GB

JMIIA0736GB

SYSTEM

HAC-19

< SYSTEM DESCRIPTION >

[AUTOMATIC AIR CONDITIONING]

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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.

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 so that front mode door moves smoothly.

HIGH IN-VEHICLE TEMPERATURE STARTING CONTROL

When front evaporator fin temperature is high [intake air temperature 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.

FRONT AUTOMATIC AIR CONDITIONING SYSTEM : Air Inlet Control

INFOID:0000000009652514

• While air inlet is in automatic control, A/C auto amp. selects air

inlet (fresh air intake, 20% fresh air intake, or recirculation)
depending on set temperature, in-vehicle temperature, and ambi-
ent temperature.

• Air inlet is fixed to 80% FRE, only when the following conditions

are satisfied:

- Air inlet is FOOT or D/F
- Ambient temperature is 2

°

C (36

°

F) or less

- Maximum fan speed

FRONT AUTOMATIC AIR CONDITIONING SYSTEM : Compressor Control

INFOID:0000000009652515

DESCRIPTION

• When the compressor activation condition is satisfied while front blower motor is activated, A/C auto amp.

transmits A/C ON signal and blower fan ON signal to BCM.

• BCM transmits the A/C ON signal and blower fan ON signal to ECM via CAN communication line. Refer to

BCS-12, "SIGNAL BUFFER SYSTEM : System Description"

.

• ECM judges the conditions of each sensor (refrigerant pressure sensor signal, accelerator position signal,

etc.), and transmits the A/C compressor request signal to IPDM E/R via CAN communication line.

• By receiving the A/C compressor request signal from ECM, IPDM E/R turns the A/C relay to ON, and acti-

vates the compressor. Refer to 

PCS-5, "RELAY CONTROL SYSTEM : System Description"

.

CONTROL BY A/C AUTO AMP.

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 the com-

pressor OFF, and stops the compressor.
When the front evaporator fin temperature returns to 4.0

°

C (39

°

F) or

more, the compressor is activated.

JMIIA0737GB

JMIIA0732GB

JMIIA1774GB

HAC-20

< SYSTEM DESCRIPTION >

[AUTOMATIC AIR CONDITIONING]

SYSTEM

CONTROL BY ECM

Compressor Protection Control at Pressure Malfunction

When the 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 (31.8 kg/cm

2

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

• 2.74 MPa (27.9 kg/cm

2

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

• 0.14 MPa (1.4 kg/cm

2

, 20 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 oil once.

Air Conditioning Cut Control

When the engine condition is high load, ECM transmit A/C relay OFF request to IPDM E/R, and stops the
compressor. Refer to 

EC-43, "AIR CONDITIONING CUT CONTROL : System Description"

.

FRONT AUTOMATIC AIR CONDITIONING SYSTEM : Door Control

INFOID:0000000009652516

DOOR MOTOR CONTROL

• LCU (Local Control Unit) is built into 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. 
• Each LCU transmits the signal of door movement completion to A/C auto amp., when the door movement is

completed.

SWITCH AND THEIR CONTROL FUNCTION

With ACCS (Advanced Climate Control System)

JMIIA1775GB

SYSTEM

HAC-21

< SYSTEM DESCRIPTION >

[AUTOMATIC AIR CONDITIONING]

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1.

Intake door

2.

Front blower motor

3.

In-cabin microfilter

4.

Front evaporator

5.

Front air mix door

6.

Front heater core

7.

Foot door

8.

Ventilator door

9.

Defroster door

10. Max. cool door

Fresh air

Recirculation air

Discharge air

Defroster

Center ventilator

Side ventilator

Front foot

Rear foot

Switch position

Door position

Front mode door

In

ta

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 do

or

Front air mix door

V

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Ma

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 co

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(Driver side)

(Pas

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AUTO switch

AUTO

JMIIA1778ZZ