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. Operational Check.
Does another symptom exist?
YES - How To Perform Trouble Diagnosis For Quick And Accurate Repair.
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. Inspection (MR20DE) or Inspection (QR25DE).
2. Check hoses for leaks or kinks.
3. Check radiator cap. Inspection (MR20DE) or Inspection (QR25DE).
OK or NG
OK - GO TO 5.
NG - Repair/replace as necessary.
5.CHECK AIR MIX DOOR OPERATION
Check and verify air mix door mechanism for smooth operation in each mode.
OK or NG
OK - GO TO 6.
NG - Adjust or replace air mix door.
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 THERMOSTAT
Check thermostat for smooth operation.
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. Changing Engine Coolant (MR20DE) or Changing Engine Coolant (QR25DE).
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. Service and Repair.