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Home >> Mercury >> 2008 >> Milan Base, 2.3 Z, Automatic >> Repair and Diagnosis >> External Pages >> Different car >> Section 1354 (HVAC Climate Control System - General Information And Diagnostics) >> Diagnostic Tests >> Climate Control System >> Pinpoint Tests >> Pinpoint Test L: Insufficient, Erratic or No Heat >> Pinpoint Test L: Insufficient, Erratic Or No Heat

Pinpoint Test L: Insufficient, Erratic Or No Heat

WARNING: This page is about a different car, the 2009 Mercury Milan, 2009 Lincoln MKZ, and 2009 Ford Fusion. However, it is still accessible from the selected car via links, so may be relevant.
  1. L1 CHECK FOR CORRECT ENGINE COOLANT LEVEL 
    • Key in OFF position.
    • Check the engine coolant level when hot and cold.
    • Is the engine coolant at the correct level (hot/cold) as indicated on the engine coolant recovery reservoir? 
    1. YES  : Go to  L3.
    2. NO  : Go to  L2.
  2. L2 CHECK THE ENGINE COOLING SYSTEM FOR LEAKS 
    • Pressure test the cooling system for leaks. Refer to ENGINE COOLING article.
    • Does the engine cooling system leak? 
    1. YES  : REPAIR the engine coolant leak. TEST the system for normal operation.
    2. NO  : Go to  L3.
  3. L3 CHECK FOR COOLANT FLOW TO THE HEATER CORE 
    • Key in ON position.
    • Run the engine until it reaches normal operation temperature. Select the FLOOR position on the control assembly. Set the temperature control to full warm and the blower to the lowest setting.
      • Fig 1: Checking Coolant Flow To Heater Core
      GF0001297Courtesy of FORD MOTOR CO.
    • Using a suitable thermo-couple temperature measuring device, check the heater core inlet hose to see if it is hot.
    • Is the heater core inlet hose hot? 
    1. YES  : Go to  L4.
    2. NO  : REFER to ENGINE COOLING article to check cooling system function.
  4. L4 CHECK FOR A PLUGGED OR RESTRICTED HEATER CORE 
      Fig 2: Check Plugged Or Restricted Heater Core
      GF0001298Courtesy of FORD MOTOR CO.
    • Using a suitable thermo-couple 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 6-17°C [10-30°F])? 
    1. YES  : Go to Pinpoint Test L  and diagnose for a blend door actuator.
    2. NO  : INSTALL a new heater core. TEST the system for normal operation.
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