Insufficient Heating

INSUFFICIENT HEATING

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 "Work Procedure" Manual Air Conditioning.
Does another symptom exist?
YES- Refer to "Symptom Table" Heater And Air Conditioning System Control Symptoms.
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. Refer to "System Inspection" Initial Inspection and Diagnostic Overview (QR25DE) or {LINK_TO:0000000007990029}, "System
Inspection" (VQ35DE).
2.Check hoses for leaks or kinks.
3.Check radiator cap. Refer to "System Inspection" Initial Inspection and Diagnostic Overview (QR25DE) or "System Inspection" Initial Inspection and Diagnostic Overview
(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 "Diagnosis Procedure" Air Mix Door Motor.

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. Refer to "Removal and Installation" Removal And Installation (QR25DE) or {LINK_TO_MANY:0000000008508663}{LINK_TO_MANY:0000000007990036}, "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 "Changing Engine Coolant" Service and Repair
(QR25DE) or "Changing Engine Coolant" 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. Refer to "HEATER CORE : Removal and Installation" Service and Repair.