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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 40 (HVAC Systems - Manual) >> Symptom Tests >> Test N: Too Cold In Vehicle (Auxiliary) >> Models With Sunroof

Models With 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. 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 correctly for 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:
    • Low coolant level.
    • Loose or worn accessory drive belt.
    • Leaking radiator or auxiliary heater hoses.
    • Kinked radiator or auxiliary heater hoses.
    • Missing radiator cap pressure seal.
    • Leaking radiator cap.
    Did you find and correct the condition? If so, go to step  18. 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. Turn ignition on. Observe the drive shaft of the auxiliary air temperature actuator. Adjust the 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  9.
  8. 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  18. If not, go to HEATING SYSTEM PERFORMANCE  under PERFORMANCE TESTS.
  9. Check the air temperature actuator (auxiliary) ignition 3 voltage circuit for an open or a high resistance. Did you find and correct the condition? If so, go to step  18. If not, go to next step.
  10. Check the auxiliary air temperature actuator ground circuit for an open. Did you find and correct the condition? If so, go to step  18. If not, go to next step.
  11. Check the auxiliary air temperature actuator temperature door control circuit for an open, a high resistance, short to ground or short to voltage. Did you find and correct the condition? If so, go to step  18. If not, go to next step.
    12. NOTE: The auxiliary HVAC control assembly connector must be connected to correctly perform test.
  12. Turn ignition on. Measure the voltage from the auxiliary temperature door control circuit of the auxiliary air temperature actuator to ground. Adjust the auxiliary air temperature switch. Does the voltage change and measure within zero-12 volts? If so, go to next step. If not, go to step  15.
  13. Inspect auxiliary air temperature actuator harness connector for poor connections. Did you find and correct the condition? If so, go to step  18. If not, go to next step.
  14. 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  18. If not, go to step  16.
  15. Inspect auxiliary HVAC control assembly harness connector for poor connections. Did you find and correct the condition? If so, go to step  18. If not, go to step  17.
  16. Replace the auxiliary air temperature actuator. See AIR TEMPERATURE ACTUATOR  under REMOVAL & INSTALLATION. After repairs are complete, go to step  18.
  17. Replace the auxiliary HVAC control assembly. See HVAC CONTROL ASSEMBLY (FRONT AUXILIARY)  under REMOVAL & INSTALLATION. After repairs are complete, go to next step.
  18. 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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