Diagnosis Procedure

WARNING: This page is about a different car, the 2009 Nissan Maxima. However, it is still accessible from the selected car via links, so may be relevant.

CHECK WITH SELF-DIAGNOSIS FUNCTION OF CONSULT-III
1. Using CONSULT-III, perform "SELF-DIAGNOSIS RESULTS" of HVAC.
2. Check if any DTC No. is displayed in the self-diagnosis results.
NOTE: If DTC is displayed along with DTC U1000 or U1010, first diagnose the DTC U1000 or U1010. Refer to "DTC LOGIC - U1000 CAN COMM CIRCUIT " or "DTC LOGIC - U1010 CONTROL UNIT (CAN) ".

Is any DTC No. displayed?

YES: Perform diagnosis for the applicable DTC. Refer to "DTC INDEX ".

NO: GO TO 2.

CHECK WITH ACTIVE TEST OF CONSULT-III

Using CONSULT-III, perform "HVAC TEST" "ACTIVE TEST" of HVAC to check each output device. Refer to "CONSULT-III FUNCTION ".
NOTE: Perform the ACTIVE TEST after starting the engine, because the A/C compressor is operating.
Check that the blower motor control signal changes according to each indicator signal.

TEST ITEM CHART

	Test item
	MODE 1	MODE 2	MODE 3	MODE 4	MODE 5	MODE 6
Mode door position	VENT1	B/L1	B/L2	FOOT	D/F	DEF
Intake door position	REC	REC	20%FRE	FRE	FRE	FRE
Air mix door position (driver & passenger side)	FULL COLD	FULL COLD	FULL HOT	FULL HOT	FULL HOT	FULL HOT
Blower motor duty ratio	37%	91%	65%	65%	65%	91%
A/C compressor (Magnet clutch)	ON	ON	ON	OFF	ON	ON

NOTE: Perform the inspection of each output device after starting the engine because the A/C compressor is operating.

Does it operate normally?

YES: Inspection End.

NO: GO TO 3.

CHECK FUSE
Check 15A fuses (Nos. 21 and 22) located in fuse block (J/B).

NOTE: Refer to "TERMINAL ARRANGEMENT " for fuse location.

Is the inspection result normal?

YES: GO TO 4.

NO: GO TO 8.
CHECK POWER SUPPLY FOR BLOWER MOTOR
1. Turn ignition switch OFF.
2. Disconnect blower motor connector.
3. Turn ignition switch ON.
4. Check voltage between blower motor harness connector M31 terminal 4 and ground.
  4 - Ground: Battery voltage
  
  Fig 1: Checking Voltage Between Blower Motor Harness Connector M31 Terminal 4 And Ground
  Courtesy of NISSAN MOTOR CO., U.S.A.
Is the inspection result normal?

YES: GO TO 5.

NO: GO TO 10.
CHECK BLOWER MOTOR GROUND CIRCUIT
1. Turn ignition switch OFF.
2. Check continuity between blower motor harness connector M31 terminal 1 and ground.
  1 - Ground: Continuity should exist.
  
  Fig 2: Checking Continuity Between Blower Motor Harness Connector M31 Terminal 1 And Ground
  Courtesy of NISSAN MOTOR CO., U.S.A.
Is the inspection result normal?

YES: GO TO 6.

NO: Repair harness or connector.
CHECK BLOWER MOTOR CIRCUIT CONTINUITY
1. Disconnect A/C auto amp. connector.
2. Check continuity between blower motor harness connector M31 (A) terminal 3 and A/C auto amp. harness connector M37 (B) terminal 32.
  3 - 32: Continuity should exist.
  
  Fig 3: Checking Continuity Between Blower Motor Connector M31 Terminal 3 And A/C Auto Amp Connector M37 Terminal 32
  Courtesy of NISSAN MOTOR CO., U.S.A.
Is the inspection result normal?

YES: GO TO 7.

NO: Repair harness or connector.
CHECK A/C AUTO AMP. OUTPUT SIGNAL
1. Reconnect blower motor connector and A/C auto amp. connector.
2. Turn ignition switch ON.
3. Set MODE switch to the VENT position.
4. Check the output waveform between blower motor harness connector M31 terminal 3 and ground using an oscilloscope, while varying the fan speed from 1 to 7.
Fig 4: Checking Waveform Between Blower Motor Harness Connector M31 Terminal 3 And Ground
Courtesy of NISSAN MOTOR CO., U.S.A.

Fig 5: Blower Fan Speed Chart
Courtesy of NISSAN MOTOR CO., U.S.A.

Is the inspection result normal?

YES: Replace the blower motor. Refer to "BLOWER MOTOR: REMOVAL AND INSTALLATION ".

NO: Replace the A/C auto amp. Refer to "REMOVAL AND INSTALLATION ".
REPLACE FUSES
1. Replace fuses.
2. Activate the blower motor.
Does the fuse blow?

YES: GO TO 9.

NO: Inspection End.
CHECK BLOWER MOTOR POWER SUPPLY CIRCUIT FOR SHORT
1. Turn ignition switch OFF.
2. Disconnect blower motor harness connector.
3. Check continuity between blower motor harness connector M31 terminal 4 and ground.
  4 - Ground: Continuity should not exist.
  
  Fig 6: Checking Continuity Between Blower Motor Harness Connector M31 Terminal 4 And Ground
  Courtesy of NISSAN MOTOR CO., U.S.A.
Is the inspection result normal?

YES: Replace blower motor. Refer to "BLOWER UNIT: REMOVAL AND INSTALLATION ".

NO: Repair harness or connector.
CHECK POWER SUPPLY OF THE BLOWER MOTOR RELAY
1. Turn the ignition switch OFF.
2. Remove the blower motor relay.
3. Turn the ignition switch ON.
4. Check the voltage between blower motor relay harness connector J-4 terminals 1, 5 and ground.
1, 5 - Ground: Battery voltage

Fig 7: Checking Voltage Between Blower Motor Relay Harness Connector J-4 Terminals 1, 5 And Ground
Courtesy of NISSAN MOTOR CO., U.S.A.

Is the inspection result normal?

YES: GO TO 11.

NO: Repair harness or connector.
CHECK BLOWER MOTOR RELAY GROUND CIRCUIT
1. Turn ignition switch OFF.
2. Check continuity between blower motor relay harness connector J-4 terminal 2 and ground.
  2 - Ground: Continuity should exist.
  
  Fig 8: Checking Continuity Between Blower Motor Relay Harness Connector J-4 Terminal 2 And Ground
  Courtesy of NISSAN MOTOR CO., U.S.A.
Is the inspection result normal?

YES: GO TO 12.

NO: Repair harness or connector.
CHECK BLOWER MOTOR SUPPLY CIRCUIT FOR OPEN
1. Disconnect A/C auto amp. connector.
2. Check continuity between blower motor harness connector M31 (A) terminal 4 and blower motor relay harness connector J-4 (B) terminal 3.
  3 - 4: Continuity should exist.
  
  Fig 9: Checking Continuity Between Blower Motor Connector M31 Terminal 4 And Blower Motor Relay Harness Connector J-4 Terminal 3
  Courtesy of NISSAN MOTOR CO., U.S.A.
Is the inspection result normal?

YES: Replace blower motor relay.

NO: Repair harness or connector.