Nissan Titan A60. Manual - part 590

BLOWER MOTOR CONTROL SYSTEM

HAC-43

< DTC/CIRCUIT DIAGNOSIS >

[AUTOMATIC AIR CONDITIONER]

C

D

E

F

G

H

J

K

L

M

A

B

HAC

N

O

P

BLOWER MOTOR CONTROL SYSTEM

System Description

INFOID:0000000006164699

SYSTEM DESCRIPTION

Component Parts

Blower speed control system components are:

• Front air control

• Variable blower control

• Front blower motor relay

• Front blower motor

• In-vehicle sensor

• Ambient sensor

• Optical sensor

• Intake sensor

System Operation

Automatic Mode

In the automatic mode, the blower motor speed is calculated by the front air control and variable blower control

based on input from the in-vehicle sensor, optical sensor, intake sensor and ambient sensor, and potentio tem-

perature control (PTC). 

When the air flow is increased, the blower motor speed is adjusted gradually 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 Blower Speed Control

Start up from cold soak condition (Automatic mode).

In a cold start up condition where the engine coolant temperature is below 50

°C (122°F), the blower will not

operate at blower speed 1 for a short period of time (up to 210 seconds). The exact start delay time varies

depending on the ambient and engine coolant temperatures.

In the most extreme case (very low ambient temperature) the blower starting delay will be 210 seconds as

described above. After the coolant temperature reaches 50

°C (122°F), or the 210 seconds has elapsed, the

blower speed will increase to the objective blower speed.

Start up from usual operating or hot soak condition (Automatic mode).

The blower will begin operation momentarily after the AUTO switch is pushed. The blower speed will gradually

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

AWIIA0411GB

HAC-44

< DTC/CIRCUIT DIAGNOSIS >

[AUTOMATIC AIR CONDITIONER]

BLOWER MOTOR CONTROL SYSTEM

When the in-vehicle temperature and the set temperature are very close, the blower will be operating at low

speed. The speed will vary depending on the sunload. During conditions of low or no sunload, the blower

operates at low speed. During high sunload conditions, the front air control causes the blower speed to

increase.

Blower Speed Control Specification

COMPONENT DESCRIPTION

Variable Blower Control

The variable blower control is located on the cooling unit. The vari-

able blower control receives a gate voltage from the front air control

to steplessly maintain the blower motor voltage in the 0 to 5 volt

range (approx.).

Front Blower Motor Component Function Check

INFOID:0000000006164700

INSPECTION FLOW

1.

CONFIRM SYMPTOM BY PERFORMING OPERATIONAL CHECK - FRONT BLOWER

1. Rotate the blower control dial clockwise once. Blower motor should operate in low speed.

2. Rotate the blower control dial clockwise, and continue checking blower speed until all speeds are

checked.

Is the inspection result normal?

YES

>> Inspection End.

NO

>> Go to diagnosis procedure. Refer to 

HAC-44, "Front Blower Motor Diagnosis Procedure"

.

Front Blower Motor Diagnosis Procedure

INFOID:0000000006164701

Regarding Wiring Diagram information, refer to 

HAC-71, "Wiring Diagram - Automatic Air Conditioner"

.

SYMPTOM: Blower motor operation is malfunctioning.

DIAGNOSTIC PROCEDURE FOR BLOWER MOTOR

WJIA0441E

WJIA0559E

BLOWER MOTOR CONTROL SYSTEM

HAC-45

< DTC/CIRCUIT DIAGNOSIS >

[AUTOMATIC AIR CONDITIONER]

C

D

E

F

G

H

J

K

L

M

A

B

HAC

N

O

P

SYMPTOM: Blower motor operation is malfunctioning under starting

blower speed control.

1.

CHECK FUSES

Check 20A fuses [No. 24 and 27 (Located in the fuse and fusible link box)]. For fuse layout. Refer to 

PG-73,

"Terminal Arrangement"

.

Is the inspection result normal?

YES

>> GO TO 2.

NO

>> GO TO 9.

2.

CHECK FRONT BLOWER MOTOR POWER SUPPLY CIRCUIT 

1. Turn ignition switch OFF.

2. Disconnect front blower motor connector.

3. Turn ignition switch ON.

4. Press the A/C switch.

5. Rotate blower control dial to maximum speed.

6. Check voltage between front blower motor harness connector

M62 terminal 2 and ground.

Is the inspection result normal?

YES

>> GO TO 11.

NO

>> GO TO 3.

3.

CHECK FRONT BLOWER MOTOR RELAY (SWITCH SIDE) POWER SUPPLY CIRCUIT

1. Turn ignition switch OFF.

2. Disconnect front blower motor relay.

3. Check voltage between front blower motor relay harness con-

nector M107 terminal 5 and ground.

Is the inspection result normal?

YES

>> GO TO 4.

NO

>> Repair harness or connector.

AWIIA1115GB

Fuses are good.

2 - Ground

: Battery voltage

WJIA1331E

5 - Ground

: Battery voltage

WJIA1886E

HAC-46

< DTC/CIRCUIT DIAGNOSIS >

[AUTOMATIC AIR CONDITIONER]

BLOWER MOTOR CONTROL SYSTEM

4.

CHECK FRONT BLOWER MOTOR RELAY

Turn ignition switch OFF.

Check front blower motor relay. Refer to 

HAC-48, "Front Blower Motor Component Inspection"

.

Is the inspection result normal?

YES

>> GO TO 5.

NO

>> Replace front blower motor relay.

5.

CHECK FRONT BLOWER MOTOR RELAY (SWITCH SIDE) CIRCUIT FOR OPEN

Check continuity between front blower motor relay harness connec-

tor M107 terminal 3 and front blower motor harness connector M62

terminal 2.

Is the inspection result normal?

YES

>> GO TO 6.

NO

>> Repair harness or connector.

6.

CHECK VARIABLE BLOWER CONTROL POWER SUPPLY CIRCUIT FOR OPEN

1. Disconnect variable blower control harness connector.

2. Check continuity between front blower motor relay harness con-

nector M107 (A) terminals 3 and variable blower control harness

connector M122 (B) terminal 4.

Is the inspection result normal?

YES

>> GO TO 7.

NO

>> Repair harness or connector.

7.

CHECK VARIABLE BLOWER CONTROL SIGNAL CIRCUIT

1. Disconnect front air control connector.

2. Check continuity between front air control harness connector

M49 (B) terminal 13 and variable blower control harness con-

nector M122 (A) terminal 3.

Is the inspection result normal?

YES

>> GO TO 8.

NO

>> Repair harness or connector.

8.

CHECK FRONT BLOWER MOTOR RELAY (COIL SIDE) POWER SUPPLY

1. Turn ignition switch ON.

2. Check voltage between front blower motor relay harness con-

nector M107 terminal 2 and ground.

Is the inspection result normal?

YES

>> GO TO 9.

NO

>> Repair front blower motor ground circuit or connector.

3 - 2

: Continuity should exist.

WJIA1360E

3 - 4

: Continuity should exist.

AWIIA0175ZZ

13 - 3

: Continuity should exist.

AWIIA0413ZZ

2 - Ground

: Battery voltage

AWIIA1386ZZ