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Nissan Sentra. Manual - part 541

HAC-12

< SYSTEM DESCRIPTION >

[AUTOMATIC AIR CONDITIONER]

SYSTEM

SYSTEM

System Diagram

INFOID:0000000009757619

System Description

INFOID:0000000009757620

• Automatic air conditioning system is controlled by each function of A/C auto amp., ECM, IPDM E/R and

BCM.

Control by A/C auto amp.

HAC-13, "Air Flow Control"

HAC-14, "Air Inlet Control"

HAC-15, "Air Outlet Control"

ALIIA0707GB

SYSTEM

HAC-13

< SYSTEM DESCRIPTION >

[AUTOMATIC AIR CONDITIONER]

HAC

HAC-15, "Compressor Control"

HAC-15, "Door Control"

HAC-20, "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 the passenger may feel. Correction is applied to the target temperature that is set using tem-

perature control dial, according to ambient temperature detected by ambient sensor.

In-vehicle sensor [in-vehicle temperature correction]

• Passenger room temperature detected by in-vehicle sensor is corrected for each front air conditioning con-

trol (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.

• 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.

Set temperature correction

• A/C auto amp. performs correction to the target temperature set by the temperature control switch so as to

match the temperature felt by the passengers depending on the ambient temperature detected by the ambi-

ent sensor, and controls it so the in-vehicle temperature is always the most suitable.

Control by ECM

- Cooling fan control

Refer to

EC-47, "COOLING FAN CONTROL : System Description"

- Air conditioning cut control

Refer to

EC-46, "AIR CONDITIONING CUT CONTROL : System Description"

Control by IPDM E/R

- Relay control

Refer to

PCS-7, "RELAY CONTROL SYSTEM : System Description"

- Cooling fan control

Refer to

EC-47, "COOLING FAN CONTROL : System Description"

Control by BCM

- Relay control

Refer to

BCS-8, "BODY CONTROL SYSTEM : System Description"

Air Flow Control

INFOID:0000000009757621

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 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 consists 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 air mix door opening angle.

• A/C auto amp. changes duty ratio of blower motor control signal and controls the air flow continuously so

that air flow matches the target air flow.

HAC-14

< SYSTEM DESCRIPTION >

[AUTOMATIC AIR CONDITIONER]

SYSTEM

• When air outlet is VENT or B/L, the minimum air flow is changed

depending on sunload.

STARTING AIR FLOW CONTROL

• When blower motor is activated, A/C auto amp. gradually

increases duty ratio of 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 blower motor

activation for a maximum of 150 seconds depending on target air

mix door opening angle. After this, blower motor control signal is

increased gradually, and 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 blower motor activation for approximately 3 seconds so that front

evaporator is cooled by refrigerant.

FAN SPEED CONTROL AT DOOR MOTOR OPERATION

When mode door motor is activated while air flow is more than the specified value, A/C auto amp. reduces fan

speed temporarily so that mode door moves smoothly.

Air Inlet Control

INFOID:0000000009757622

The intake door is automatically controlled by the temperature set-

ting, ambient temperature, in-vehicle temperature, intake tempera-

ture, amount of sunload and ON/OFF operation of the compressor.

Intake door automatic control selects FRE, 20% FRE, or REC

depending on a target air mix door opening angle, based on in-vehi-

cle temperature, ambient temperature, and sunload.

JMIIA1129GB

JMIIA1130GB

JMIIA1227GB

JMIIA0711GB

SYSTEM

HAC-15

< SYSTEM DESCRIPTION >

[AUTOMATIC AIR CONDITIONER]

HAC

Air Outlet Control

INFOID:0000000009757623

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

mode door position depending on a target 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.

Compressor Control

INFOID:0000000009757624

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 BCM.

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

• ECM judges that the compressor can be activated depending on the state of each sensor (refrigerant pres-

sure sensor signal and others) and transmits A/C compressor request signal to IPDM E/R via CAN commu-

nication.

• 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

°C (36°F) or less, A/C auto amp. requests ECM to turn compres-

sor OFF, and stops the compressor.

• When the front evaporator fin temperature returns to 3.5

°C (38°F)

or more, the compressor is activated.

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-46, "AIR CONDITIONING CUT CONTROL : System Description"

Door Control

INFOID:0000000009757625

AIR MIX DOOR MOTOR (DRIVER SIDE)

DESCRIPTION

• The step motor system is adopted for air mix door motor (driver side).

• When a drive signal is input from A/C auto amp. to door motor, a step motor built into the door motor rotates

according to the drive signal, and then stops at the target door position.

JMIIA0710GB

JMIIA1055GB

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