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Home >> Infiniti >> 2016 >> QX70 AWD >> Repair and Diagnosis >> Heating, Ventilation & A/C (HVAC) >> HVAC Control Systems >> Heater & Air Conditioning System (Automatic Air Conditioner) (Basic Inspection And Circuit Diagnosis) >> Circuit Diagnosis >> Blower Motor >> Diagnosis Procedure

Diagnosis Procedure

  1. PERFORM SELF - DIAGNOSIS

    Perform self - diagnosis function STEP - 4. Refer to DIAGNOSIS DESCRIPTION  (WITHOUT ACCS) or DIAGNOSIS DESCRIPTION  (WITH ACCS).

    Code No. 41 42 43 44 45 46
    Blower motor duty ratio 37% 91% 65% 91%

    Does blower motor speed change according to each code No.?

    YES 

    INSPECTION END

    NO 

    GO TO STEP 2  .

  2. CHECK POWER SUPPLY FOR BLOWER MOTOR

    1. Disconnect blower motor connector.
    2. Turn ignition switch ON.
    3. Check voltage between blower motor harness connector and ground.
      (+) (-) Voltage
      Blower motor -
      Connector Terminal
      M109 1 Ground Battery voltage

    Is the inspection result normal?

    YES 

    GO TO STEP 3  .

    NO 

    GO TO STEP 6  .

  3. CHECK BLOWER MOTOR GROUND CIRCUIT

    1. Turn ignition switch OFF.
    2. Check continuity between blower motor harness connector and ground.
      Blower motor - Continuity
      Connector Terminal
      M109 3 Ground Existed

    Is the inspection result normal?

    YES 

    GO TO STEP 4  .

    NO 

    Repair harness or connector.

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

    1. Disconnect unified meter and A/C amp. connector.
    2. Check continuity between blower motor harness connector and unified meter and A/C amp. harness connector.
      Blower motor Unified meter and A/C amp. Continuity
      Connector Terminal Connector Terminal
      M109 2 M66 38 Existed
    3. Check continuity between blower motor harness connector and ground.
      Blower motor - Continuity
      Connector Terminal
      M109 2 ground Not existed

    Is the inspection result normal?

    YES 

    GO TO STEP 5  .

    NO 

    Repair harness or connector.

  5. CHECK UNIFIED METER AND A/C AMP. OUTPUT SIGNAL

    1. Reconnect blower motor connector and unified meter and A/C amp. connector.
    2. Turn ignition switch ON.
    3. Set MODE switch to VENT position.
    4. Change fan speed from Lo to Hi, and check duty ratios between blower motor harness connector and ground by using an oscilloscope. Normal terminal 2 drive signal duty ratios are shown in the table below.
      G05226200Courtesy of NISSAN NORTH AMERICA, INC.

    Is the inspection result normal?

    YES 

    Replace blower motor after confirming the fan air flow does not change.

    NO 

    Replace unified meter and A/C amp.

  6. CHECK POWER VOLTAGE OF BLOWER RELAY

    1. Turn ignition switch OFF.
    2. Remove blower relay. Refer to FUSE, CONNECTOR AND TERMINAL ARRANGEMENT .
    3. Turn ignition switch ON.
    4. Check the voltage between blower relay fuse block terminals and ground. Refer to DESCRIPTION for relay terminal assignment.
    (+) (-) Voltage
    Blower relay -
    1 Ground Battery voltage
    3

    Is the inspection result normal?

    YES 

    GO TO STEP 7  .

    NO 

    Check ignition power supply circuit. Refer to WIRING DIAGRAM - IGNITION POWER SUPPLY - .

  7. CHECK BLOWER RELAY

    1. Turn ignition switch OFF.
    2. Install blower relay. Refer to FUSE, CONNECTOR AND TERMINAL ARRANGEMENT .
    3. Check operation sound of the blower relay after switching ignition switch ON.

    Is the inspection result normal?

    YES 

    GO TO STEP 8  .

    NO 

    Replace blower relay.

  8. CHECK FUSE

    Check fuse 15A [Nos. 21 and 22, located in the fuse block (J/B)]. Refer to FUSE, CONNECTOR AND TERMINAL ARRANGEMENT .

    Is the inspection result normal?

    YES 

    Repair harness or connector.

    NO 

    Be sure to eliminate cause of malfunction before installing new fuse.

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