Pinpoint Test

CHECK FOR CORRECT ENGINE COOLANT LEVEL
1. Ignition OFF.
2. Check the engine coolant level.
  Is the engine coolant at the correct level as indicated on the engine coolant recovery reservoir?
  - Yes: GO to 2 .
  - No : REFER to DIAGNOSTIC ROUTINE A : Loss of Coolant.
CHECK FOR COOLANT FLOW TO THE HEATER CORE
1. Run the engine until it reaches normal operating temperature. Select the floor position. Set the temperature control to full warm and the blower to the lowest setting.
2. Using a suitable temperature measuring device, check the heater core inlet hose to see if it is hot.
  Is the heater core inlet hose temperature above 66 C (150 F)?
  - Yes: GO to 3 .
  - No : REFER to DIAGNOSTIC ROUTINE C : The Engine Does Not Reach Normal Operating Temperature.
CHECK FOR A PLUGGED OR RESTRICTED HEATER CORE
1. Using a suitable temperature measuring device, measure the heater core outlet hose temperature.
  Is the heater core outlet hose temperature similar to the inlet hose temperature (within approximately 6 C (43 F) - 17 C (63 F))?
  - Yes: DIAGNOSE the temperature blend door actuator. REFER to Diagnostic Routine N: The Temperature Control is inoperative or Does Not Operate Correctly .
  - No : INSTALL a new heater core. REFER to Heater Core Heater Core .