Nissan Frontier. Manual - part 870

HAC-34

< DTC/CIRCUIT DIAGNOSIS >

[AUTOMATIC AIR CONDITIONER]

INTAKE DOOR MOTOR

Intake door motor

The intake door motor is attached to the intake unit. It rotates so that

air is drawn from inlets set by the front air control. Motor rotation is

conveyed to a lever which activates the intake door.

Intake Door Motor Component Function Check

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INSPECTION FLOW

1.

CONFIRM SYMPTOM BY PERFORMING OPERATIONAL CHECK - REC (

)

1. Press the mode switch to vent mode(

).

2. Press REC (

) switch. The REC (

)indicator should illuminate.

3. Press REC (

) switch again. The REC (

) indicator should go out.

4. Listen for intake door position change (you should hear blower sound change slightly).
Is the inspection result normal?

YES

>> Inspection End.

NO

>> Go to diagnosis procedure. Refer to 

HAC-34, "Intake Door Motor Diagnosis Procedure"

.

Intake Door Motor Diagnosis Procedure

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Regarding Wiring Diagram information, refer to 

HAC-63, "Wiring Diagram - Automatic Air Conditioner"

.

SYMPTOM:

• Intake door does not change.

• Intake door motor does not operate normally.

DIAGNOSTIC PROCEDURE FOR INTAKE DOOR MOTOR

1.

CHECK INTAKE DOOR MOTOR CIRCUITS FOR OPEN AND SHORT TO GROUND 

1. Turn ignition switch OFF.

2. Disconnect the front air control harness connector M52 (A) and

the intake door motor harness connector M58 (B).

3. Check continuity between front air control harness connector

M52 (A) terminals 21, 22 and the intake door motor harness

connector M58 (B) terminals 1, 6.

WJIA1486E

A

B

Continuity

Connector

Terminal

Connector

Terminal

M52

21

M58

6

Yes

22

1

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INTAKE DOOR MOTOR

HAC-35

< DTC/CIRCUIT DIAGNOSIS >

[AUTOMATIC AIR CONDITIONER]

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4. Check continuity between front air control harness connector

M52 terminals 21, 22 and ground.

Is the inspection result normal?

YES

>> GO TO 3.

NO

>> Repair or replace harness as necessary.

2.

CHECK FRONT AIR CONTROL FOR INTAKE AIR DOOR MOTOR POWER AND GROUND 

1. Reconnect front air control harness connector.

2. Turn ignition switch ON.

3. Check voltage between front air control harness connector M52

terminal 21 and terminal 22 while placing the HVAC system into

self-diagnostic mode.

Is the inspection result normal?

YES

>> Inspect intake air door for binding or mechanical failure. If intake air door moves freely, replace the

intake air door motor. Refer to 

VTL-20, "Removal and Installation"

.

NO

>> Replace front air control. Refer to 

VTL-7, "Removal and Installation"

.

Connector

Terminal

—

Continuity

M52

21

Ground

No

22

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Connector

Terminals

Condition Voltage 

(Approx.)

(+) (-)

M52

21

22

Self-diagnostic mode (opening)

Battery voltage

22

21

Self-diagnostic mode (closing)

Battery voltage

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HAC-36

< DTC/CIRCUIT DIAGNOSIS >

[AUTOMATIC AIR CONDITIONER]

BLOWER MOTOR CONTROL SYSTEM

BLOWER MOTOR CONTROL SYSTEM

System Description

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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

BLOWER MOTOR CONTROL SYSTEM

HAC-37

< DTC/CIRCUIT DIAGNOSIS >

[AUTOMATIC AIR CONDITIONER]

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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 (1) is located on the cooling unit. The

variable blower control receives a gate voltage from the front air con-

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

range (approx.).

Front Blower Motor Component Function Check

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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-37, "Front Blower Motor Diagnosis Procedure"

.

Front Blower Motor Diagnosis Procedure

INFOID:0000000009478287

Regarding Wiring Diagram information, refer to 

HAC-63, "Wiring Diagram - Automatic Air Conditioner"

.

SYMPTOM: Blower motor operation is malfunctioning.

DIAGNOSTIC PROCEDURE FOR BLOWER MOTOR

WJIA0441E

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