Infiniti FX35 / FX45. Manual - part 117

ATC-64

< SERVICE INFORMATION >

TROUBLE DIAGNOSIS

• Intake sensor

System Operation

The intake door control determines intake door position based on the ambient temperature, the intake air tem-
perature and the in-vehicle temperature. When the DEF, or OFF switches are pressed or A/C switch is OFF,
the unified meter and A/C amp. sets the intake door at the FRE position.

Intake Door Control Specification

COMPONENT DESCRIPTION

Intake Door Motor

The intake door motor is attached to the blower unit. It rotates so that
air is drawn from inlets set by the unified meter and A/C amp. Motor
rotation is conveyed to a lever which activates the intake door.

DIAGNOSIS PROCEDURE FOR INTAKE DOOR MOTOR

SYMPTOM: Intake door motor does not operate normally.
Perform diagnosis procedure. Refer to 

ATC-54, "LAN System Circuit"

.

Blower Motor Circuit

INFOID:0000000001328189

SYMPTOM: Blower motor operation is malfunctioning.

INSPECTION FLOW

SJIA1588E

RJIA1787E

RJIA0897E

TROUBLE DIAGNOSIS

ATC-65

< SERVICE INFORMATION >

C

D

E

F

G

H

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A

B

ATC

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SYSTEM DESCRIPTION

Component Parts

Fan speed control system components are:

• Unified meter and A/C amp.
• A/C LAN system (PBR built-in mode door motor, air mix door motor and intake door motor)
• In-vehicle sensor
• Ambient sensor
• Sunload sensor

*1

ATC-50, "Operational Check"

*2

ATC-43, "Self-Diagnosis Function"

, 

see No. 4.

*3

ATC-43, "Self-Diagnosis Function"

, 

see No. 6.

*4

ATC-86, "Ambient Sensor Circuit"

*5

ATC-88, "In-vehicle Sensor Circuit"

*6

ATC-91, "Sunload Sensor Circuit"

*7

ATC-94, "Intake Sensor Circuit"

*8

ATC-32, "How to Perform Trouble Di-
agnosis for Quick and Accurate Re-
pair"

*9

ATC-43, "Self-Diagnosis Function"

, 

see No. 13.

*10 "DIAGNOSIS PROCEDURE FOR 

BLOWER MOTOR"

*11

EC-193

 (VQ35DE) or 

EC-779

 

(VK45DE)

SJIA1808E

ATC-66

< SERVICE INFORMATION >

TROUBLE DIAGNOSIS

• Intake sensor

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 will 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 starting delay will be 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 will increase 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 will gradu-
ally rise 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 will be operating at low
speed. The low speed will vary 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

RJIA1995E

RJIA1996E

TROUBLE DIAGNOSIS

ATC-67

< SERVICE INFORMATION >

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COMPONENT DESCRIPTION

Brush-Less Motor

The blower motor utilizes a brush-less motor with a rotating magnet.
Quietness is improved over previous motors where the brush was
the point of contact and the coil rotated.

DIAGNOSIS PROCEDURE FOR BLOWER MOTOR

SYMPTOM: Blower motor operation is malfunctioning.

1.

CHECK POWER SUPPLY FOR BLOWER MOTOR

1.

Disconnect blower motor connector.

2.

Turn ignition switch ON.

3.

Check voltage between blower motor harness connector M78
terminal 1 and ground.

OK or NG

OK

>> GO TO 2.

NG

>>

Check power supply circuit and 15A fuses [Nos. 10
and 11, located in the fuse block (J/B)]. Refer to 

PG-

77

.

• If fuses are OK, check harness for open circuit. Repair

or replace if necessary.

• If fuses are NG, check harness for short circuit and replace fuse.

2.

CHECK BLOWER MOTOR GROUND CIRCUIT

1.

Turn ignition switch OFF.

2.

Check continuity between blower motor harness connector M78
terminal 3 and ground.

OK or NG

OK

>> GO TO 3.

NG

>> Repair harness or connector.

3.

CHECK CIRCUIT CONTINUITY BETWEEN BLOWER MOTOR AND UNIFIED METER AND A/C AMP.

1.

Disconnect unified meter and A/C amp. connector.

ZHA152H

SJIA0266E

1 – Ground

: Battery voltage

RJIA1997E

3 – Ground

: Continuity should exist.

RJIA1998E