Nissan Sentra B18 (2020-2025) Service Manual: Blower Motor

Diagnosis Procedure

1. CHECK FUSE

   1. 1. Ignition switch OFF.

      2. Check 30A fuse [No. 55, located in fuse block (J/B)].

   Is the inspection result normal?

   YES >>

   GO TO 2.

   NO >>

   Replace the blown fuse after repairing the affected circuit.

2. CHECK BLOWER MOTOR POWER SUPPLY

   1. 1. Disconnect blower motor connector.

      2. Ignition switch ON.

      3. Check voltage between blower motor harness connector and ground.

         +		—		Voltage (Approx.)
         Blower motor
         Connector	Terminal
         M62	2	Ground		Battery voltage

   Is the inspection result normal?

   YES >>

   GO TO 3.

   NO >>

   Repair harness or connector.

3. CHECK BLOWER MOTOR GROUND CIRCUIT

   1. 1. Ignition switch OFF.

      2. Check continuity between blower motor harness connector and ground.

         Blower motor		—		Continuity
         Connector	Terminal
         M62	4	Ground		Yes

   Is the inspection result normal?

   YES >>

   GO TO 4.

   NO >>

   Repair harness or connector.

4. CHECK BLOWER MOTOR CONTROL SIGNAL CIRCUIT

   1. 1. Disconnect A/C amp. connector.

      2. Check continuity between blower motor harness connector and A/C amp. harness connector.

         Blower motor		A/C amp.		Continuity
         Connector	Terminal	Connector	Terminal
         M62	1	M81	34	Yes

   Is the inspection result normal?

   YES >>

   GO TO 5.

   NO >>

   Repair the harness or connector.

5. CHECK BLOWER MOTOR CONTROL SIGNAL

   1. 1. Reconnect blower motor connector and A/C amp. connector.

      2. Ignition switch ON.

      3. Operate MODE switch to set air outlet to VENT.

      4. Change fan speed from Lo to Hi, and check duty ratios between blower motor harness connector and ground by using an oscilloscope.

         Note:

         Calculate drive signal duty ratio as shown in the figure.

         T2 = Approx. 1.6 ms

         

         Blower motor		Condition	Duty ratio (Approx.)
         Connector	Terminal	Fan speed (manual) VENT mode
         M62	1	1st	25 %
         		2nd	33 %
         		3rd	41 %
         		4th	51 %
         		5th	61 %
         		6th	69 %
         		7th	81 %

   Is the inspection result normal?

   YES >>

   Replace blower motor. Refer to Removal and Installation.

   NO >>

   Replace A/C amp. Refer to Removal and Installation.

Component Inspection (blower Motor)

1. CHECK BLOWER MOTOR

   1. 1. Connect battery voltage to terminal 2 of blower motor.

      2. Connect ground to terminal 4 of blower motor.

   Does the blower fan operate?

   YES>>

   Intermittent incident. Refer to Intermittent Incident.

   NO>>

   Replace blower motor. Refer to Removal and Installation.

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