Nissan GT-R. Manual - part 164

HAC-18

< SYSTEM DESCRIPTION >

[AUTOMATIC AIR CONDITIONER]

BLOWER MOTOR CONTROL SYSTEM

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

Low Coolant Temperature Starting Control

• It stops the blower motor for approximately 150 seconds at the maximum according to the target air mix door

position based on the calculation result of A/C auto amp. and engine coolant temperature [approximately
56

°

C (133

°

F) or less] when starting the automatic air flow control. Then, it increases the duty ratios gently so

as not to blow cold air underfoot. 

• Change the increase rate of the duty ratio to the normal automatic air flow control when the engine coolant

temperature is approximately 56

°

C (133

°

F) or more in the starting air flow control at low coolant tempera-

ture. 

High In-vehicle Temperature Starting Control

Turn the blower motor to OFF while the evaporator is cooled by the refrigerant (approximately 3 seconds) to
prevent the hot air from blowing out when the evaporator temperature is high [approximately 35

°

C (95

°

F) or

more of intake sensor detection temperature] at starting the blower motor. 

Fan Speed Control at Door Motor Operation

When the mode door motor operated at the air flow automatic control, it decreases the air flow of the blower
motor once and controls it so that the mode door motor moves smoothly. 

Fan Speed Control at Voice Recognition

When the voice command switch is operated at the air flow automatic control, it decreases the air flow of the
blower motor once and controls it so as not to disturb the voice recognition function. In addition, this control
continues while the voice recognition function is operating.

MAGNET CLUTCH CONTROL SYSTEM

HAC-19

< SYSTEM DESCRIPTION >

[AUTOMATIC AIR CONDITIONER]

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MAGNET CLUTCH CONTROL SYSTEM

System Diagram

INFOID:0000000009163981

System Description

INFOID:0000000009163982

SYSTEM OPERATION

• When A/C switch, AUTO switch, DEF switch is pressed or when shifting mode position D/F, A/C auto amp.

transmits A/C switch signal and blower fan motor switch signal to ECM, via CAN communication.

• ECM judges whether compressor can be turned ON, based on each sensor status (refrigerant-pressure sen-

sor signal, throttle angle, etc.). If it judges compressor can be turned ON, it sends A/C compressor request
signal to IPDM E/R, via CAN communication.

• Upon receipt of A/C compressor request signal from ECM, IPDM E/R turns A/C relay ON to operate com-

pressor.

• When sending A/C compressor request signal to IPDM E/R via CAN communication line, ECM simulta-

neously sends A/C compressor feedback signal to A/C auto amp. via CAN communication line.

• ECM sends A/C compressor feedback signal to A/C auto amp., then, uses input A/C compressor feedback

signal to control air inlet.

COMPRESSOR PROTECTION CONTROL

Compressor Protection Control at Pressure Malfunction

The high-pressure side pressure detected by the refrigerant pressure sensor is approximately 3,120 kPa (31.8
kg/cm

2

, 452 psi) or more when the engine speed is less than 1,500 rpm. It is approximately 2,740 kPa (27.9

kg/cm

2

, 397 psi) when the engine speed is 1,500 rpm or more. When it is approximately 120 kPa (1.2 kg/cm

2

,

17 psi) or less, ECM turns the A/C relay to OFF and stops the compressor. 

Compressor Oil Circulation Control

When the engine coolant temperature is approximately 56

°

C (133

°

F) or less, it turns the compressor to ON at

the engine start for approximately 6 seconds and circulates the compressor oil. 

Low Temperature Protection Control

It turns the A/C relay OFF and stops the compressor by the signal from A/C auto amp. according to the evap-
orator passing air temperature detected by the intake sensor. 

NNIIA0133GB

HAC-20

< SYSTEM DESCRIPTION >

[AUTOMATIC AIR CONDITIONER]

MAGNET CLUTCH CONTROL SYSTEM

It turns the compressor to OFF when the evaporator passing air tem-
perature becomes 

−

5

°

C (23

°

F) or less. In addition, it turns the com-

pressor to ON when the evaporator passing air temperature
becomes 1

°

C (34

°

F) or more. 

Operating Rate Control

It controls the operating rate of the compressor by the ambient temperature when the set temperature is set to
any condition other than the full cold or when the air outlet is “VENT”, “B/L”, or “FOOT”. 

Air Conditioner Cut Control

ECM turns the A/C relay to OFF and stops the compressor at engine high load. 

Fail-safe Control

When a communication malfunction between A/C auto amp. and AV control unit and preset switch is continu-
ing for approximately 30 seconds or more, the A/C auto amp. automatically controls air outlet and fan speed,
fixes the air inlet to fresh air intake, maintains the set temperature data before the communication malfunction
occurred, and turns the compressor to ON. Turn the compressor to ON with the following conditions if the con-
dition before the communication error occurs was A/C switch OFF. 

SJIA0267E

CAN COMMUNICATION SYSTEM

HAC-21

< SYSTEM DESCRIPTION >

[AUTOMATIC AIR CONDITIONER]

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CAN COMMUNICATION SYSTEM

Description

INFOID:0000000009163983

CAN (Controller Area Network) is a serial communication line for real time applications. It is an on board multi-
plex communication line with high data communication speed and excellent error detection ability. A modern
vehicle is equipped with many ECMs, and each control unit shares information and links with other control
units during operation (not independent). In CAN communication, 2 control units are connected with 2 commu-
nication 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. Refer to 

LAN-11, "CAN System

Specification Chart"

.