Diagnosis Procedure

WARNING: This page is about a different car, the 2018 Nissan Titan XD and 2018 Nissan Titan. However, it is still accessible from the selected car via links, so may be relevant.

Symptom

Insufficient heating
No warm air comes out. (Air flow volume is normal.)

CONFIRM SYMPTOM BY PERFORMING OPERATION CHECK - TEMPERATURE INCREASE
1. Turn temperature control dial clockwise to maximum heat.
2. Check for hot air at discharge air outlets.
Can a symptom be duplicated?

YES

GO TO 3 .

NO

GO TO 2 .
CHECK FOR ANY SYMPTOMS
Perform a complete operational check and 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.

GO TO 4 .
CHECK ENGINE COOLING SYSTEM
1. Check for proper engine coolant level. Refer to Removal and Installation .
2. Check hoses for leaks or kinks.
3. Check radiator cap. Refer to Removal and Installation .
4. Check for air in cooling system.
GO TO 5 .
CHECK AIR MIX DOOR MOTOR OPERATION
Check and verify air mix door mechanism for smooth operation.

Does air mix door operate correctly?

YES

GO TO 6 .

NO

Check the air mix door motor circuit. Refer to Diagnosis Procedure .
CHECK AIR DUCTS
Check for disconnected or leaking air ducts.

Is the inspection result normal?

YES

GO TO 7 .

YES

GO TO 8 .

NO

Repair all disconnected or leaking air ducts.
CHECK PTC HEATER
Check PTC heater. Refer to Diagnosis Procedure .

Is the inspection result normal?

YES

GO TO 8 .

NO

Replace PTC heater. Refer to Removal and Installation .
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

GO TO 9 .

NO

Both hoses warm: GO TO 10 .
CHECK ENGINE COOLANT SYSTEM
Check thermostat operation. Refer to System Inspection .

Is the inspection result normal?

YES

System OK.

NO

Repair or replace as necessary.
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 .
4. To retest: GO TO 11 .
CHECK HEATER HOSE TEMPERATURES
1. Start engine and warm 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 .