Insufficient Heating

INSUFFICIENT HEATING

Component Function Check

SYMPTOM: Insufficient heating

INSPECTION FLOW

SYMPTOM: Insufficient heating

1. CONFIRM SYMPTOM BY PERFORMING OPERATION CHECK - TEMPERATURE INCREASE

1.Press the AUTO switch.
2.Turn temperature control dial (LH) clockwise until 32�C (90�F) is displayed.
3.Check for hot air at discharge air outlets.
Can a symptom be duplicated?
YES- GO TO 3
NO- GO TO 2

2. CHECK FOR ANY SYMPTOMS

Perform a complete operational check and check for any symptoms. Refer to Automatic Air Conditioning.
Does another symptom exist?
YES- Symptom Matrix Chart.
NO- System OK.

3. CHECK FOR SERVICE BULLETINS

Check for any service bulletins.

- GO TO 4

4. CHECK ENGINE COOLING SYSTEM

1.Check for proper engine coolant level. Initial Inspection and Diagnostic Overview (QR25DE) or (VQ35DE).
2.Check hoses for leaks or kinks.
3.Check radiator cap. Initial Inspection and Diagnostic Overview (QR25DE) or
(VQ35DE).
4.Check for air in cooling system.
- GO TO 5

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. Automatic Air Conditioning.

6. CHECK AIR DUCTS

Check for disconnected or leaking air ducts.
Is the inspection result normal?
YES- GO TO 7
NO- Repair all disconnected or leaking air ducts.

7. 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 8
NO- Both hoses warm: GO TO 9

8. CHECK ENGINE COOLANT SYSTEM

Check thermostat operation. Service and Repair (QR25DE) or Service and Repair (VQ35DE).
Is the inspection result normal?
YES- System OK.
NO- Repair or replace as necessary.

9. 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. Service and Repair
(QR25DE) or Service and Repair (VQ35DE).
4.To retest GO TO 10

10. 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 Service and Repair.