Nissan Sentra B18 (2020-2025) Service Manual / Ventilation, Heater & Air Conditioner / Heater & Air Conditioning Control System :: Automatic Air Conditioner / Dtc/circuit Diagnosis / Blower Motor

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

Diagnosis Procedure

Diagnosis Procedure

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.

CHECK BLOWER MOTOR POWER SUPPLY

Disconnect blower motor connector.
Ignition switch ON.

Check voltage between blower motor harness connector and ground.

+	—	Voltage (Approx.)
M62	2	Ground	Battery voltage

—

Voltage

(Approx.)

Blower motor

Connector

Terminal

M62

Ground

Battery voltage

Is the inspection result normal?

YES >>

GO TO 3.

NO >>

Repair harness or connector.

CHECK BLOWER MOTOR GROUND CIRCUIT

Ignition switch OFF.

Check continuity between blower motor harness connector and ground.

Blower motor		—		Continuity
Connector	Terminal	—		Continuity
M62	4	Ground		Yes

Is the inspection result normal?

YES >>

GO TO 4.

NO >>

Repair harness or connector.

CHECK BLOWER MOTOR CONTROL SIGNAL CIRCUIT

Disconnect A/C auto amp. connector.

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

Blower motor		A/C auto amp.		Continuity
Connector	Terminal	Connector	Terminal	Continuity
M62	1	M33	34	Yes

Is the inspection result normal?

YES >>

GO TO 5.

NO >>

Repair the harness or connector.

CHECK BLOWER MOTOR CONTROL SIGNAL

Reconnect blower motor connector and A/C auto amp. connector.
Ignition switch ON.
Operate MODE switch to set air outlet to VENT.

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	Duty ratio (Approx.)
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 auto amp. Refer to Removal and Installation.

Component Inspection (blower Motor)

Component Inspection (Blower Motor)

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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