Nissan Murano Z51. Manual - part 845

BLOWER MOTOR CONTROL SYSTEM

HAC-35

< SYSTEM DESCRIPTION >

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BLOWER MOTOR CONTROL SYSTEM

System Diagram

INFOID:0000000005514590

System Description

INFOID:0000000005514591

Blower speed is automatically controlled by the temperature setting, ambient temperature, in-vehicle tempera-
ture, intake temperature, amount of sunload and air mix door position.
By pressing the AUTO switch, the blower motor starts to gradually increase air flow volume.
When engine coolant temperature is low, the blower motor operation is delayed to prevent cool air from flow-
ing.

SYSTEM OPERATION

System operation

• For air flow, the manual selection (1-7) with the fan control dial has

priority. 

• If the AUTO switch is pressed or if the DEF switch is pressed while

in the OFF condition, it changes to the automatic control by A/C
auto amp. 

• When increasing the air flow, it changes the duty ratio of the blower

motor drive signal to prevent the air flow from suddenly increasing. 

• There are the following types of air flow control: starting air flow

control, starting air flow control at low coolant temperature, starting
air flow control at high in-vehicle temperature, and air flow control
at actuator operation in addition to manual control, normal auto-
matic air flow control. 

Normal automatic air flow control

• When the target temperature is set by the temperature control switch of A/C control, the A/C auto amp. per-

forms the calculation and decides the target according to the signal from each sensor. 

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

so that the air flow becomes the target air flow. 

• The minimum air flow will change according to the sunload when the air discharge outlet is VENT or B/L. 

JSIIA1540GB

JSIIA0999ZZ

HAC-36

< SYSTEM DESCRIPTION >

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BLOWER MOTOR CONTROL SYSTEM

Fan Speed Control Specification

Starting air flow control

• When starting the automatic control of air flow, the system gradually increases the duty ratio of the blower

motor drive signal to prevent too much air from blowing. 

• The time period from when the air flow changes from LO to HI is approximately 8 seconds. 
• It becomes the starting air flow control at low coolant temperature according to the calculation result of the A/

C auto amp. and engine coolant temperature [approximately 58

°

C (136

°

F) or less] during the automatic air

flow control. 

• Do not perform the starting air flow control when the air discharge outlet is set to DEF. 

Starting Fan Speed Control

Start up from COLD SOAK Condition (Automatic mode)
In cold start up condition where the engine coolant temperature is below 58

°

C (136

°

F), the blower does not

operate for a short period of time (up to 150 seconds). The exact start delay time varies depending on the
ambient temperature and engine coolant temperature.
In the most extreme case (very low ambient temperature) the blower start delay is 150 seconds as described
above. After this delay, the blower will operate at low speed until the engine coolant temperature rises above
58

°

C (136

°

F), and then the blower speed increases to the objective speed.

Start up from usual or HOT SOAK Condition (Automatic mode)
The blower will begin operation momentarily after the AUTO switch is pressed. The blower speed rises gradu-
ally to the objective speed over a time period of 3 seconds or less (actual time depends on the objective
blower speed).

JPIIA0635GB

MAGNET CLUTCH CONTROL SYSTEM

HAC-37

< SYSTEM DESCRIPTION >

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MAGNET CLUTCH CONTROL SYSTEM

System Diagram

INFOID:0000000005514592

System Description

INFOID:0000000005514593

The A/C auto amp. controls compressor operation by ambient temperature, intake air temperature and signal
from ECM.

SYSTEM OPERATION

When the A/C switch, the AUTO switch, or the DEF switch is pressed, or when shifting mode position D/F, A/C
auto amp. transmit the A/C switch signal and blower fan motor switch signal to the ECM, via CAN communica-
tion.
ECM judges whether compressor can be turned ON, based on each sensor status (refrigerant-pressure sen-
sor signal, throttle angle, etc.). If the ECM judges that the compressor can be turned ON, it sends A/C com-
pressor request signal to the IPDM E/R, via CAN communication.
Upon receipt of A/C compressor request signal from the ECM, the IPDM E/R turns the A/C relay ON to oper-
ate the compressor.
When sending A/C compressor request signal to the IPDM E/R via CAN communication line, the ECM simul-
taneously sends A/C compressor feedback signal to A/C auto amp. via CAN communication line.
The ECM sends A/C compressor feedback signal to A/C auto amp., then, uses input A/C compressor feed-
back signal to control air inlet.

Compressor Protection Control

The ECM makes the A/C relay turn OFF and stops the compressor when pressure on the high-pressure side
detected by the refrigerant pressure sensor is over approximately 3,119 kPa (31.8 kg/cm

2

, 452 psi), or below

approximately 118 kPa (1.2 kg/cm

2

, 17 psi).

Low Temperature Protection Control

Turn the A/C relay to OFF and stop the compressor by the signal from the A/C auto amp according to the
evaporator passing air temperature detected by the intake sensor and the ambient temperature detected by
the ambient sensor. 

JSIIA1541GB

HAC-38

< SYSTEM DESCRIPTION >

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CAN COMMUNICATION SYSTEM

CAN COMMUNICATION SYSTEM

System Description

INFOID:0000000005514594

CAN (Controller Area Network) is a serial communication line for real time application. It is an on-vehicle mul-
tiplex communication line with high data communication speed and excellent error detection ability. Many elec-
tronic control units are equipped onto each vehicle, and each control unit shares information and links with
other control units during operation (not independent). In CAN communication, control units are connected
with 2 communication lines (CAN-H line, CAN-L line) allowing a high rate of information transmission with less
wiring. Each control unit transmits/receives data but selectively reads required data only. For details, refer to

LAN-27, "CAN System Specification Chart"

.