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Test J: Blower Motor Malfunction - Auxiliary

WARNING: This page is about a different car, the 2002 GMC Savana Special, 2002 GMC Savana Camper Special, 2002 GMC Savana, and 2002 Chevrolet Chevy Express. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: For circuit reference, see CONNECTOR IDENTIFICATION  and/or WIRING DIAGRAMS  .
NOTE: Definition: The auxiliary blower motor operates in at least one, but not all, speed positions.
  1. If review of system operation has been performed, go to next step. If review of system operation has not been performed, see DESCRIPTION  and OPERATION  .
  2. Turn ignition on. Place front auxiliary blower switch in each speed position. If blower motor operates correctly in each speed position, go to next step. If blower motor does not operate correctly in each speed position, go to step  5.
  3. If vehicle is equipped with both front and rear auxiliary HVAC control assemblies, go to next step. If vehicle is not equipped with both front and rear auxiliary HVAC control assemblies, problem is intermittent. Check wiring and harness connectors for damage or defects and poor connections.
  4. Place front auxiliary blower switch in REAR CNTL position. Place rear auxiliary blower switch in each speed position. If auxiliary blower motor operates correctly in each speed position, problem is intermittent. Check wiring and harness connectors for damage or defects and poor connections. If auxiliary blower motor does not operate correctly in each speed position, go to step  13.
  5. Turn ignition off. Disconnect harness connector from auxiliary blower motor. Turn ignition on. Using a test light connected to ground, probe auxiliary blower motor voltage supply circuit (Yellow wire) at auxiliary blower motor harness connector. Place front auxiliary blower switch in each speed position. If test light illuminates in each speed position, go to step  12. If test light does not illuminate in each speed position, go to next step.
  6. Turn ignition off. Disconnect harness connector from auxiliary blower motor resistor. Turn ignition on. Using a test light connected to ground, probe each blower speed circuit terminal of resistor connector while placing front auxiliary blower switch in the appropriate speed position being tested. If test light illuminates on each speed circuit, go to step  20. If test light does not illuminate on speed circuit being tested, go to next step.
  7. Check applicable blower speed circuit for an open or high resistance between auxiliary blower motor resistor and corresponding auxiliary blower motor relay. See WIRING DIAGRAMS . If an open or high resistance was found, repair as necessary and go to step  33. If an open or high resistance was not found, go to next step.
  8. Turn ignition off. Disconnect harness connector from applicable auxiliary blower motor relay. See Figure. Turn ignition on. Using a test light connected to ground, probe ignition 3 voltage circuit (Brown wire) at harness connector of blower motor relay. See WIRING DIAGRAMS . If test light illuminates, go to next step. If test light does not illuminate, go to step  25.
  9. Using a test light connected to ground, probe positive battery voltage circuit (Red wire) at harness connector of applicable auxiliary blower motor relay. If test light illuminates, go to next step. If test light does not illuminate, go to step  26.
  10. Using a test light connected to positive battery voltage, probe control circuit at harness connector of applicable auxiliary blower motor relay. See WIRING DIAGRAMS . Place front auxiliary blower switch in the appropriate position for circuit being tested. If test light illuminates, go to step  19. If test light does not illuminate, go to next step.
  11. Check applicable control circuit of auxiliary blower motor relay for an open or high resistance between relay and front auxiliary HVAC control assembly. See WIRING DIAGRAMS . If an open or high resistance was found, repair as necessary and go to step  33. If an open or high resistance was not found, go to step  22.
  12. Check auxiliary blower motor ground circuit (Black wire) for high resistance. See WIRING DIAGRAMS . If high resistance was found, repair as necessary and go to step  33. If high resistance was not found, go to step  21.
  13. If auxiliary blower motor operates in any rear auxiliary blower switch speed position, go to next step. If auxiliary blower motor does not operate in any rear auxiliary blower switch speed position, go to step  15.
  14. Check applicable blower motor control circuit between rear auxiliary HVAC control assembly and the splice for an open or high resistance. See WIRING DIAGRAMS . If an open or high resistance was found, repair as necessary and go to step  33. If an open or high resistance was not found, go to step  23.
  15. Turn ignition off. Disconnect harness connector from front auxiliary HVAC control assembly. Turn ignition on. Place rear auxiliary blower switch in maximum speed position. Connect a 3-amp fused jumper wire between auxiliary blower switch control circuit (Light Blue wire) at front auxiliary HVAC control assembly harness connector and ground. If auxiliary blower motor operates, go to step  22. If auxiliary blower motor does not operate, go to next step.
  16. Turn ignition off. Disconnect harness connector from auxiliary HVAC control processor. Turn ignition on. Connect a 3-amp fused jumper wire between auxiliary blower switch control circuit (Light Blue wire) at auxiliary HVAC control processor harness connector and ground. If auxiliary blower motor operates, go to next step. If auxiliary blower motor does not operate, go to step  18.
  17. Check auxiliary blower switch control circuit (Light Blue wire) between front auxiliary HVAC control assembly and auxiliary HVAC control processor for an open or high resistance. See WIRING DIAGRAMS . If an open or high resistance was found, repair as necessary and go to step  33. If an open or high resistance was not found, go to step  24.
  18. Check auxiliary blower switch control circuit (Dark Blue wire) between rear auxiliary HVAC control assembly and auxiliary HVAC control processor for an open or high resistance. See WIRING DIAGRAMS . If an open or high resistance was found, repair as necessary and go to step  33. If an open or high resistance was not found, go to step  23.
  19. Check harness connector at applicable auxiliary blower motor relay for a poor connection. If a poor connection was found, repair as necessary and go to step  33. If a poor connection was not found, go to step  27.
  20. Check harness connector at auxiliary blower motor resistor for a poor connection. If a poor connection was found, repair as necessary and go to step  33. If a poor connection was not found, go to step  28.
  21. Check harness connector at auxiliary blower motor for a poor connection. If a poor connection was found, repair as necessary and go to step  33. If a poor connection was not found, go to step  29.
  22. Check harness connector at auxiliary blower switch (rear auxiliary heat only) or front auxiliary HVAC control assembly (auxiliary HVAC) for a poor connection. If a poor connection was found, repair as necessary and go to step  33. If a poor connection was not found, go to step  30.
  23. Check harness connector at rear auxiliary HVAC control assembly for a poor connection. If a poor connection was found, repair as necessary and go to step  33. If a poor connection was not found, go to step  31.
  24. Check harness connector at auxiliary HVAC control processor for a poor connection. If a poor connection was found, repair as necessary and go to step  33. If a poor connection was not found, go to step  32.
  25. Repair the open or high resistance condition in ignition 3 voltage circuit (Brown wire) between auxiliary blower motor relay and the splice. See WIRING DIAGRAMS . If repair is complete, go to step  33.
  26. Repair the open or high resistance condition in positive battery voltage circuit (Red wire) between auxiliary blower motor relay and the splice. See WIRING DIAGRAMS . If repair is complete, go to step  33.
  27. Replace the appropriate auxiliary blower motor relay. See Figure. After repairs are complete, go to step  33.
  28. Replace auxiliary blower motor resistor. After repairs are complete, go to step  33.
  29. Replace auxiliary blower motor. See BLOWER MOTORS  under REMOVAL & INSTALLATION. After repairs are complete, go to step  33.
  30. Replace front auxiliary blower switch (rear auxiliary heat only) or front auxiliary HVAC control assembly (auxiliary HVAC). See FRONT AUXILIARY BLOWER SWITCH  or FRONT AUXILIARY HVAC CONTROL ASSEMBLY  under REMOVAL & INSTALLATION. After repairs are complete, go to step  33.
  31. Replace rear auxiliary HVAC control assembly. See REAR AUXILIARY HVAC CONTROL ASSEMBLY  under REMOVAL & INSTALLATION. After repairs are complete, go to step  33.
  32. Replace auxiliary HVAC control processor. See AUXILIARY HVAC CONTROL PROCESSOR  under REMOVAL & INSTALLATION. If replacement is complete, go to next step.
  33. Operate system to verify repair. If the condition was corrected, system is okay. If the condition was not corrected, return to step  2.
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