Insufficient Heating

TROUBLE DIAGNOSIS


Insufficient Heating

SYMPTOM: Insufficient heating

INSPECTION FLOW
1.CONFIRM SYMPTOM BY PERFORMING OPERATIONAL CHECK - TEMPERATURE INCREASE
1. Turn temperature control dial clockwise to maximum heat position.
2. Check for hot air at discharge air outlets.
Can the symptom be duplicated?
YES >> GO TO 3.
NO >> GO TO 2.
2.CHECK FOR ANY SYMPTOMS
Perform a complete operational check for any symptoms. Refer to Operational Check .
Does another symptom exist?
YES >> Refer to Initial Inspection and Diagnostic Overview .
NO >> System OK.
3.CHECK FOR SERVICE BULLETINS
Check for any service bulletins.
>> GO TO 4.
4.CHECK COOLANT SYSTEM
1. Check engine coolant level. Refer to Testing and Inspection (HR16DE) or Testing and Inspection (MR18DE).
2. Check hoses for leaks or kinks.
3. Check Radiator cap. Refer to Testing and Inspection
OK or NG
OK >> GO TO 5.
NG >> Repair/replace as necessary.
5.CHECK AIR MIX DOOR CABLE
Check air mix door cable operation. Refer to Air Mix Door Cable Adjustment .
OK or NG
YES >> GO TO 6.
NO >> Adjust or replace air mix door cable. Refer to Air Mix Door Cable Adjustment .
6.CHECK AIR DUCTS
Check ducts for air leaks.
OK or NG
OK >> GO TO 7.
NG >> Repair air leaks.
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 inlet hose hot and the outlet hose warm?
YES >> GO TO 8.
NO >> Both hoses warm: GO TO 9.
8.CHECK ENGINE COOLANT TEMPERATURE SENSOR
Check engine control temperature sensor. Refer to P0117 (MR TYPE 1), P0117 (MR TYPE 2) or P0117 (HR16DE).
OK or NG
OK >> System OK.
NG >> Repair or replace as necessary. Retest.
9.CHECK HEATER HOSES
Check heater hoses for proper installation.
OK or NG
OK >> GO TO 10.
NG >> Repair /replace as necessary. Retest GO TO 7.
10.BACK FLUSH HEATER CORE
1. Back flush heater core.
2. Drain the water from the system.
3. Refill system with new engine coolant. Refer to Service and Repair (HR16DE) or Service and Repair (MR18DE) .
4. Start engine and warm it up to normal operating temperature.
5. Touch both the inlet and outlet heater hoses.
Is the inlet hose hot and the outlet hose warm?
YES >> System OK.
NO >> Replace heater core and refill engine coolant. Refer to Service and Repair .