Infiniti G37 Coupe. Manual - part 768

INTAKE DOOR CONTROL SYSTEM

HAC-61

< FUNCTION DIAGNOSIS >

[AUTOMATIC AIR CONDITIONER]

C

D

E

F

G

H

J

K

L

M

A

B

HAC

N

O

P

Intake door position is basically fixed at FRE when FRE indicator
lamps of DEF switch and intake switch turn ON, and fixed at REC
when REC indicator lamp of intake switch turns ON.
Intake door automatic control selects FRE, 20 - 80%FRE, or REC
depending on a target air mix door opening angle, based on in-vehi-
cle temperature, ambient temperature, and sunload.

RJIA4067E

HAC-62

< FUNCTION DIAGNOSIS >

[AUTOMATIC AIR CONDITIONER]

BLOWER MOTOR CONTROL SYSTEM

BLOWER MOTOR CONTROL SYSTEM

WITHOUT LEFT AND RIGHT VENTILATION TEMPERATURE SEPARATELY
CONTROL SYSTEM

WITHOUT LEFT AND RIGHT VENTILATION TEMPERATURE SEPARATELY CON-
TROL SYSTEM : System Diagram

INFOID:0000000001734532

WITHOUT LEFT AND RIGHT VENTILATION TEMPERATURE SEPARATELY CON-
TROL SYSTEM : System Description

INFOID:0000000001734533

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.
With pressing AUTO switch, the blower motor starts to increase gradually air flow volume.
When engine coolant temperature is low, the blower motor operation is delayed to prevent cool air from flow-
ing.

SYSTEM OPERATION

Automatic Mode

In the automatic mode, the blower motor speed is calculated by the unified meter and A/C amp. based on the
input from the PBR, in-vehicle sensor, sunload sensor, intake sensor and ambient sensor.
When the air flow is increased, the duty ratio of the blower fan motor’s drive signal is changed at 8%/sec. to
prevent a sudden increase in air flow.
In addition to manual air flow control and the usual automatic air flow control, starting air flow control, low
water temperature starting control and high passenger compartment temperature starting control are avail-
able.

Starting Fan Speed Control

Start up from COLD SOAK Condition (Automatic mode)
In a cold start up condition where the engine coolant temperature is below 56

°

C (133

°

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 and engine coolant temperature.
In the most extreme case (very low ambient) 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 56

°

C (133

°

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).

Blower Speed Compensation

Sunload

JSIIA0778GB

BLOWER MOTOR CONTROL SYSTEM

HAC-63

< FUNCTION DIAGNOSIS >

[AUTOMATIC AIR CONDITIONER]

C

D

E

F

G

H

J

K

L

M

A

B

HAC

N

O

P

When the in-vehicle temperature and the set temperature are very close, the blower operates at low speed.
The low speed varies depending on the sunload. During conditions of low or no sunload, the blower speed is
at duty ratio 25%. During high sunload conditions, the unified meter and A/C amp. raise the blower speed
(duty ratio 49%).

Fan Speed Control Specification

WITH LEFT AND RIGHT VENTILATION TEMPERATURE SEPARATELY CON-
TROL SYSTEM

WITH LEFT AND RIGHT VENTILATION TEMPERATURE SEPARATELY CONTROL 
SYSTEM : System Diagram

INFOID:0000000001734534

WITH LEFT AND RIGHT VENTILATION TEMPERATURE SEPARATELY CONTROL 
SYSTEM : System Description

INFOID:0000000001734535

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.
With pressing AUTO switch, the blower motor starts to increase gradually air flow volume.
When engine coolant temperature is low, the blower motor operation is delayed to prevent cool air from flow-
ing.

SYSTEM OPERATION

Automatic Mode

In the automatic mode, the blower motor speed is calculated by the unified meter and A/C amp. based on the
input from the PBR, in-vehicle sensor, sunload sensor, intake sensor and ambient sensor.
When the air flow is increased, the duty ratio of the blower fan motor’s drive signal is changed at 8%/sec. to
prevent a sudden increase in air flow.

RJIA1609E

JSIIA0780GB

HAC-64

< FUNCTION DIAGNOSIS >

[AUTOMATIC AIR CONDITIONER]

BLOWER MOTOR CONTROL SYSTEM

In addition to manual air flow control and the usual automatic air flow control, starting air flow control, low
water temperature starting control and high passenger compartment temperature starting control are avail-
able.

Starting Fan Speed Control

Start up from COLD SOAK Condition (Automatic mode)
In a cold start up condition where the engine coolant temperature is below 56

°

C (133

°

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 and engine coolant temperature.
In the most extreme case (very low ambient) 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 56

°

C (133

°

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).

Blower Speed Compensation

Sunload
When the in-vehicle temperature and the set temperature are very close, the blower operates at low speed.
The low speed varies depending on the sunload. During conditions of low or no sunload, the blower speed is
at duty ratio 25%. During high sunload conditions, the unified meter and A/C amp. raise the blower speed
(duty ratio 49%).

Fan Speed Control Specification

RJIA1609E