Inspection Flow

WARNING: This page is about a different car, the 2019 Nissan NV3500 HD, 2019 Nissan NV2500 HD, and 2019 Nissan NV1500. However, it is still accessible from the selected car via links, so may be relevant.

CONFIRM SYMPTOM BY PERFORMING OPERATIONAL CHECK - TEMPERATURE INCREASE
1. Rotate the blower control dial to the low speed.
2. Turn temperature control dial clockwise to maximum heat.
3. Check for hot air at discharge air outlets.
Can the symptom be duplicated?

YES

GO TO 3.

NO

GO TO 2.
CHECK FOR ANY SYMPTOMS
Perform a complete operational check for any symptoms. Refer to Work Procedure .

Does another symptom exist?

YES

Refer to Symptom Table .

NO

System OK.
CHECK FOR SERVICE BULLETINS
Check for any service bulletins.

Are there any pertinent service bulletins?

YES

Perform service bulletin actions.

NO

GO TO 4.
CHECK FOR DTCS
With CONSULT
1. Turn ignition switch ON.
2. Select "Self Diagnostic Result" mode of "HVAC".
3. Check DTC.
Is any DTC detected?

YES

DTC Index .

NO

GO TO 5.
CHECK ENGINE COOLING SYSTEM
1. Check for proper engine coolant level. Refer to System Inspection (VQ40DE) or Inspection (VK56VD).
2. Check hoses for leaks or kinks.
3. Check radiator cap. Refer to System Inspection (VQ40DE) or Inspection (VK56VD).
4. Check for air in cooling system.
GO TO 6.
CHECK AIR MIX DOOR OPERATION - TEMPERATURE DECREASE
1. Rotate temperature control dial counterclockwise until maximum cold.
2. Check for cold air at appropriate discharge air outlets.
Is the test result normal?

YES

GO TO 7.

NO

Check front air mix door for mechanical failure. Refer to Removal and Installation - Front Air Mix Door Motor .
CHECK AIR DUCTS
Check ducts for air leaks.

Is the inspection result normal?

YES

GO TO 8.

NO

Repair air leaks. Refer to Exploded View .
CHECK HEATER HOSE TEMPERATURES
1. Start engine and warm it up to normal operating temperature.
2. Touch both the inlet and outlet heater hoses. The inlet hose should be hot and the outlet hose should be warm.
Is the inspection result normal?

YES

Hot inlet hose and a warm outlet hose: GO TO 9.

NO

GO TO 10.
CHECK ENGINE COOLANT SYSTEM
Check engine control temperature sensor. Refer to Component Inspection (VQ40DE), Component Inspection (Engine Coolant Temperature Sensor 1) (Sensor 1 VQ56VD) or Component Inspection (Engine Coolant Temperature Sensor 2) (Sensor 2 VQ56VD).

Is the inspection result normal?

YES

System OK.

NO

Repair or replace as necessary. Retest.
CHECK HEATER HOSES
Check heater hoses for proper installation.

Is the inspection result normal?

YES

System OK.

NO
1. Back flush heater core.
2. Drain the water from the system.
3. Refill system with new engine coolant. Refer to Changing Engine Coolant . (VQ40DE) or Changing Engine Coolant (VQ56DE)
4. GO TO 11 to retest.
CHECK HEATER HOSE TEMPERATURES
1. Start engine and warm it up to normal operating temperature.
2. Touch both the inlet and outlet heater hoses. The inlet hose should be hot and the outlet hose should be warm.
Is the inspection result normal?

YES

System OK.

NO

Replace heater core. Refer to Removal and Installation - Front Heater Core .