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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 B: Air Delivery Improper (Auxiliary) >> Models With Sunroof

Models With Sunroof

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  1. Perform SYSTEM OPERATION CHECK  under TROUBLE SHOOTING. Go to next step.
  2. Turn ignition on. Place the I/P HVAC control assembly to the rear position. Place the front auxiliary HVAC control assembly blower control in the OFF position. Is the auxiliary blower motor OFF? If so, go to next step. If not, go to TEST E: BLOWER MOTOR ALWAYS ON (AUXILIARY) 
    3. NOTE: This step tests for a auxiliary blower motor that does not operate regardless of the desired blower motor speed.
  3. Place the front auxiliary HVAC control assembly blower control in each mode 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. NOTE: This step tests for a auxiliary blower motor that operates, yet does not accurately respond to the desired blower motor speed.
  4. Does the auxiliary blower motor operate correctly for each mode position? If so, go to next step. If not, go to TEST I: BLOWER MOTOR MALFUNCTION (AUXILIARY) .
    5. NOTE: This step tests for an inoperative auxiliary mode actuator in one mode position(s) or in the wrong mode position(s).
  5. Place the front auxiliary HVAC control assembly blower control in the HIGH position. Place the front auxiliary HVAC control assembly mode control in each mode position. Does the auxiliary mode actuator operate correctly for each mode position? If so, check for intermittent and poor connections. If not, go to next step.
  6. Check the front auxiliary HVAC control assembly ignition 3 voltage circuit for an open, a high resistance or a short to ground. Did you find and correct the condition? If so, go to step  19. If not, go to next step.
  7. Check the front auxiliary HVAC control assembly ground circuit for an open. Did you find and correct the condition? If so, go to step  19. If not, go to next step.
  8. Check the auxiliary mode actuator ignition 3 voltage circuit for an open or a high resistance. Did you find and correct the condition? If so, go to step  19. If not, go to next step.
  9. Check the auxiliary mode actuator ground circuit for an open. Did you find and correct the condition? If so, go to step  19. If not, go to next step.
    10. NOTE: The front auxiliary HVAC control assembly mode switch control circuit will normally vary between zero-12 volts.
  10. Measure the voltage from the auxiliary mode door control circuit at the auxiliary mode actuator to ground. Place the front auxiliary HVAC control assembly mode control in each mode position. Does the voltage measure less than 12 volts in each mode position? If so, go to next step. If not, go to step  12.
  11. Does the voltage measure near zero volts in each mode position? If so, go to step  13. If not, go to step  15.
  12. Check the auxiliary mode door control circuit for a short to voltage. Did you find and correct the condition? If so, go to step  19. If not, go to step  14.
  13. Check the auxiliary mode door control circuit for an open, a high resistance or a short to ground. Did you find and correct the condition? If so, go to step  19. If not, go to next step.
  14. Inspect the front auxiliary HVAC control assembly harness connector for poor connections. Did you find and correct the condition? If so, go to step  19. If not, go to step  17.
  15. Inspect the auxiliary mode actuator harness connector for poor connections. Did you find and correct the condition? If so, go to step  19. If not, go to next step.
    16. NOTE: An incorrectly installed auxiliary mode actuator, damaged attaching linkages. Any mechanical repairs will not require the mode actuator (auxiliary) to be replaced.
  16. Check the auxiliary mode actuator, door and any attaching linkage for any binding. Inspect the duct work for any debris that would prevent air to flow through the duct work. Did you find and correct the condition? If so, go to step  19. If not, go to step  18.
  17. Replace the front auxiliary HVAC control assembly. See HVAC CONTROL ASSEMBLY (FRONT AUXILIARY)  under REMOVAL & INSTALLATION. After repairs are complete, go to step  19.
  18. Replace the auxiliary mode actuator. See MODE ACTUATOR (AUXILIARY)  under REMOVAL & INSTALLATION. After repairs are complete, go to next step.
  19. 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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