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INSPECTION PROCEDURE 8: Poor heater performance
 
 
TECHNICAL DESCRIPTION (COMMENT)
If the blower air temperature cannot be warmed when raising the preset temperature, the engine cooling system or A/C controller assembly (A/C-ECU).
 
 
TROUBLESHOOTING HINT
  • Insufficient volume of engine coolant
  • Malfunction of the heater components (water pump, thermostat, heater passage)
  • Malfunction of the blower motor
  • Malfunction of the air mixing damper
  • Malfunction of the A/C controller assembly (A/C-ECU)
  • The air refresher clogged
 
 
DIAGNOSIS
STEP 1. Check the air refresher.
Is the air refresher clogged?
Is the check result normal?
Go to Step 2.
Replace the air refresher (Refer to ).
 
STEP 2. Check the engine coolant level.
Check that the coolant level in the condenser tank is between "F" and "L".
Is the engine coolant level correct?
Go to Step 3.
Adjust the engine coolant level (Refer to GROUP 14 - On-vehicle Service, Engine Coolant Change ).
 
STEP 3. Using scan tool (M.U.T.-IIISE), check other system DTC.
Check if DTC is set in the ECM.
Is the DTC set?
Repair the DFI and MFI system (Refer to GROUP 13A - Diagnostic Trouble Code Chart ).
Go to Step 4.
 
STEP 4. Check the heater components.
Check the following items.
  • Water pump operation
  • Thermostat operation
  • Heater passage is clogged
  • Air intrusion into the heater passage
  • Blower motor operation
  • Air mixing damper stuck
  • Air mixing damper control motor stuck
Is the check result normal?
Go to Step 5.
Repair or replace the part(s) having damage or other problems.
 
STEP 5. Check again that the heater works normally.
Is the check result normal?
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points, How to Cope with Intermittent Malfunctions ).
Replace the A/C controller assembly (A/C-ECU).