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Models Without Sunroof

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  1. Perform SYSTEM OPERATION CHECK  under TROUBLE SHOOTING. Go to next step.
    2. NOTE: This step ensures that the primary HVAC system is functioning properly.
    NOTE: The auxiliary HVAC control assembly operates independently of the HVAC control assembly to provide heated airflow through the auxiliary system.
  2. Does the HVAC control assembly operate and provide sufficient heating? If so, go to next step. If not, go to TEST M: TOO COLD IN VEHICLE .
  3. Turn ignition on. Select REAR CNTL on the front auxiliary HVAC control assembly. Place the A/C auxiliary blower motor switch in each speed position. Does the auxiliary blower motor operate at all? If so, go to next step. If not, go to TEST G: BLOWER MOTOR INOPERATIVE (AUXILIARY) .
  4. Does the auxiliary blower motor operate at the desired speed in each speed position? If so, go to next step. If not, go to TEST I: BLOWER MOTOR MALFUNCTION (AUXILIARY) .
    5. NOTE: If the condition does not occur when a heating request has been made then you must bypass the A/C compressor and cooling system diagnostic information.
  5. Inspect the cooling system for a low coolant level, a loose or worn accessory drive belt, a leaking radiator or auxiliary heater hoses, a kinked radiator or auxiliary heater hoses, a missing radiator cap pressure seal and a leaking radiator cap. Did you find and correct the condition? If so, go to step  30. If not, go to next step.
  6. Start the engine. Place the blower motor switch in the OFF position. Place the A/C request switch in the OFF position. Does the A/C compressor operate? If so, go to TEST J: COMPRESSOR CLUTCH DOES NOT DISENGAGE . If not, go to next step.
    7. NOTE: This step ensures that the rear auxiliary HVAC control assembly is able to move the auxiliary air temperature actuator.
  7. Turn ignition on. Select REAR CNTL on the front auxiliary HVAC control assembly. Observe the drive shaft of the auxiliary air temperature actuator. Adjust the rear auxiliary air temperature switch. Does the auxiliary air temperature actuator drive shaft rotate at all? If so, go to next step. If not, go to step  10.
    8. NOTE: This step ensures that the rear auxiliary HVAC control assembly is able to move the auxiliary air temperature actuator.
  8. Select OFF on the front auxiliary HVAC control assembly. Place the front auxiliary air temperature switch from the coldest to hottest position. Does the auxiliary air temperature actuator drive shaft rotate at all? If so, go to next step. If not, go to step  13.
  9. Inspect the auxiliary air temperature door and the auxiliary air temperature actuator for:
    • Misaligned auxiliary air temperature actuator.
    • Broken or binding linkages or auxiliary air temperature door.
    • Obstruction that prevents the auxiliary air temperature door from operating within its full range of motion.
    • Missing seals to the auxiliary air temperature door.
    • Misaligned seals to the auxiliary air temperature door.
    Did you find and correct the condition? If so, go to step  30. If not, go to HEATING SYSTEM PERFORMANCE  under PERFORMANCE TESTS.
  10. Select OFF on the front auxiliary HVAC control assembly. Place the front auxiliary air temperature switch from the coldest to hottest position. Does the auxiliary air temperature actuator drive shaft rotate at all? If so, go to next step. If not, go to step  16.
  11. Check the rear auxiliary HVAC control assembly rear auxiliary temperature door control circuit for an open, high resistance, a short to ground or short to voltage. Did you find and correct the condition? If so, go to step  30. If not, go to next step.
    12. NOTE: The circuit that is to be tested runs between the rear auxiliary HVAC control assembly and the auxiliary HVAC control processor. The circuit is the position signal from the rear auxiliary HVAC control assembly for the auxiliary air temperature actuator. The circuit only provides a reference when the front auxiliary HVAC control assembly is in the REAR CNTL position.
    NOTE: The rear auxiliary HVAC control assembly connector must be connected to correctly perform test.
  12. Turn ignition on. Measure the voltage from the rear auxiliary temperature door control circuit of the rear auxiliary HVAC control assembly to ground. Place the front auxiliary air temperature switch from the coldest to hottest position. Does the voltage change and measure within zero-12 volts? If so, go to step  25. If not, go to step  23.
  13. Check the HVAC control assembly ignition 3 voltage circuit front auxiliary for an open or a high resistance. Did you find and correct the condition? If so, go to step  30. If not, go to next step.
  14. Check the front auxiliary HVAC control assembly air temperature door position signal circuit for an open, high resistance, a short to ground or short to voltage. Did you find and correct the condition? If so, go to step  30. If not, go to next step.
    15. NOTE: The circuit that is to be tested runs between the front auxiliary HVAC control assembly and the auxiliary HVAC control processor. The circuit is the position signal from the rear auxiliary HVAC control assembly for the auxiliary air temperature actuator. The circuit only provides a reference when the front auxiliary HVAC control assembly is in any other position than REAR CNTL.
    NOTE: The front auxiliary HVAC control assembly connector must be connected to correctly perform test.
  15. Turn ignition on. Measure the voltage from the air temperature door position signal circuit of the front auxiliary HVAC control assembly to ground. Place the front auxiliary air temperature switch from the coldest to hottest position. Does the voltage change and measure within zero-12 volts? If so, go to step  25. If not, go to step  24.
  16. Check the auxiliary HVAC processor ignition 3 voltage circuit for an open or a high resistance. Did you find and correct the condition? If so, go to step  30. If not, go to next step.
  17. Check the auxiliary air temperature actuator ignition 3 voltage circuit for an open or a high resistance. Did you find and correct the condition? If so, go to step  30. If not, go to next step.
  18. Check the auxiliary air temperature actuator ground circuit for an open. Did you find and correct the condition? If so, go to step  30. If not, go to next step.
  19. Check the auxiliary air temperature actuator auxiliary temperature door control circuit for an open, high resistance, a short to ground or short to voltage. Did you find and correct the condition? If so, go to step  30. If not, go to next step.
    20. NOTE: This step checks the output of the auxiliary HVAC control processor to the auxiliary air temperature actuator.
    NOTE: The auxiliary HVAC control processor, front and rear auxiliary HVAC control assembly connectors must be connected to correctly perform test.
  20. Turn ignition on. Select REAR CNTL on the front auxiliary HVAC control assembly. Measure the voltage from the auxiliary temperature door control circuit of the auxiliary air temperature actuator to ground. Place the front auxiliary air temperature switch from the coldest to hottest position. Does the voltage change and measure within zero-12 volts? If so, go to next step. If not, go to step  25.
  21. Inspect auxiliary air temperature actuator harness connector for poor connections. Did you find and correct the condition? If so, go to step  30. If not, go to next step.
  22. Inspect the auxiliary air temperature actuator, door and any attaching linkage for binding or a condition that prevents drive shaft rotation. Did you find and correct the condition? If so, go to step  30. If not, go to step  26.
  23. Inspect rear auxiliary HVAC control assembly harness connector for poor connections. Did you find and correct the condition? If so, go to step  30. If not, go to step  27.
  24. Inspect front auxiliary HVAC control assembly harness connector for poor connections. Did you find and correct the condition? If so, go to step  30. If not, go to step  28.
  25. Inspect auxiliary HVAC control processor harness connector for poor connections. Did you find and correct the condition? If so, go to step  30. If not, go to step  29.
  26. Replace the auxiliary air temperature actuator. See AIR TEMPERATURE ACTUATOR (AUXILIARY)  under REMOVAL & INSTALLATION. After repairs are complete, go to step  30.
  27. Replace the rear auxiliary HVAC control assembly. See HVAC CONTROL PROCESSOR (AUXILIARY)  under REMOVAL & INSTALLATION. After repairs are complete, go to step  30.
  28. Replace the front auxiliary HVAC control assembly. See HVAC CONTROL PROCESSOR (AUXILIARY)  under REMOVAL & INSTALLATION. After repairs are complete, go to step  30.
  29. Replace the auxiliary HVAC control processor. See HVAC CONTROL PROCESSOR (AUXILIARY)  under REMOVAL & INSTALLATION. After repairs are complete, go to next step.
  30. Operate the system in order to verify the repair. Did you correct the condition? If so, system is okay. If not, go to step  2.
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