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Heating Performance Diagnostic

WARNING: This page is about a different car, the 2002 Chevrolet Malibu. However, it is still accessible from the selected car via links, so may be relevant.
WARNING: Avoid contact with moving parts and hot surfaces while working around a running engine in order to prevent physical injury.
  1. Were you sent here from TEST I: TOO COLD IN VEHICLE ? If so, go to next step. If not, go to TEST I: TOO COLD IN VEHICLE .
  2. Start the engine. Allow the engine to idle. Does the engine reach a normal operating temperature? If so, go to next step. If not, go to step  9.
  3. Allow to idle. Select the FLOOR mode. Select the minimum blower speed. Select the maximum temperature setting. Feel the temperature of the inlet and outlet hoses at the heater core. Does the inlet hose feel warmer than the outlet hose? If so, go to step  7. If not, go to next step.
  4. Install a thermometer into the I/P center air outlet. Secure a thermometer to the heater core outlet hose. Select the panel mode. Select the maximum blower speed. Select the maximum temperature setting. Record the temperature at the I/P center air outlet and the heater core outlet hose. Compare the recorded temperatures. Are the temperatures similar? If so, go to next step. If not, go to step  6.
  5. Inspect and repair the following areas of the vehicle for cold air leaks:
    • The Cowl
    • The Recirculation Door
    • The HVAC Module Case
    Perform the necessary repairs. After repairs are complete, go to step  10.
  6. Inspect the temperature door operation. Perform any necessary repairs. Are the repairs complete? After repairs are complete, go to step  10.
  7. Turn off the engine. Backflush the heater core. Start the engine. Select the FLOOR mode. Select the minimum blower speed. Select the maximum temperature setting. Feel the temperature of the inlet and outlet hoses at the heater core. Does the inlet hose feel warmer than the outlet hose? If so, go to next step. If not, go to step  10.
  8. Replace the heater core. After repairs are complete, go to step  10.
  9. Repair the low engine temperature concern. After repairs are complete, go to step  10.
  10. Operate the system in order to verify the repair. Does the system operate correctly? If so, system is okay. If not, go to step  2.
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