Component Function Check

SYMPTOM: Insufficient heating

INSPECTION FLOW

1. 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

2. CHECK FOR ANY SYMPTOMS

Perform a complete operational check and check for any symptoms. Refer to HAC-102, "Description & Conditions".

Does another symptom exist? YES >> Refer to HAC-155, "Symptom Matrix Chart".

NO >> System OK.

3. CHECK FOR SERVICE BULLETINS

Check for any service bulletins.

>> GO TO 4

4. CHECK ENGINE COOLING SYSEM

1. Check for proper engine coolant level. Refer to CO-11, "System Inspection" (QR25DE) or CO-34, "System Inspection" (VQ35DE).

2. Check hoses for leaks or kinks.

3. Check radiator cap. Refer to CO-11, "System Inspection" (QR25DE) or CO-34, "System Inspection" (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. Refer to HAC-122, "Diagnosis Procedure".

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.

Is the inspection result normal? YES >> Hot inlet hose and a warm outlet hose: GO TO 8

NO >> Both hoses warm: GO TO 9

8. CHECK ENGINE COOLANT SYSTEM

Check thermostat operation. Refer to CO-21, "Removal and Installation" (QR25DE) or CO-46, "Removal and Installation" (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. Refer to CO-12, "Changing Engine Coolant" (QR25DE) or CO-35, "Changing Engine Coolant" (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.

Is the inspection result normal? YES >> System OK.

NO >> Replace heater core Refer to VTL-22, "Removal and Installation".