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 Description And Conditions.
Does another symptom exist?
YES - Refer to 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. Refer to Testing and Inspection (QR25DE) or Testing and Inspection (VQ35DE).
2. Check hoses for leaks or kinks.
3. Check radiator cap. Refer to Testing and Inspection (QR25DE) or Testing and 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 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 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. Refer to 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 Refer to Service and Repair.