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Test G: Blower Motor Malfunction

NOTE: For circuit reference, see CONNECTOR IDENTIFICATION  and/or WIRING DIAGRAMS  .
NOTE: Definition: The blower motor operates in at least one, but not all, speed positions.
  1. Did you review the DESCRIPTION & OPERATION  and perform SYMPTOM DIAGNOSIS? If so, go to next step. If not, see SYMPTOM DIAGNOSIS  under TROUBLE SHOOTING.
  2. Turn ignition on. Place mode control in VENT position. Place blower motor switch in each speed position. If blower motor operates in each speed position, go to next step. If blower motor does not operate in each speed position, go to step  4.
  3. Place blower motor switch in maximum speed position. Place mode control in each position. If blower motor operates in each position, problem is intermittent. Check wiring and connections. If blower motor does not operate in each speed position, go to step  18.
  4. Turn ignition off. Disconnect blower motor. Turn ignition on. Connect a test light between blower motor supply voltage circuit of the blower motor and ground. Place blower motor switch in each speed position. If test light illuminates in each speed position, go to step  16. If test light does not illuminate in each speed position, go to next step.
  5. If test light illuminates in maximum speed position, go to step  10. If test light does not illuminate in maximum speed position, go to next step.
  6. Turn ignition off. Disconnect blower motor relay. Turn ignition on. Connect a test light between Orange wire at blower motor relay terminal No. 87 and ground. If test light illuminates, go to next step. If test light does not illuminate, go to step  19.
  7. Place blower motor switch in maximum speed position. Using a test light connected to ground, probe battery voltage circuit of the blower motor relay. If test light illuminates, go to step  9. If test light does not illuminate, go to next step.
  8. Check for an open or high resistance in high blower motor control circuit of the blower motor relay. Repair as necessary, then go to step  24. If circuit is okay, go to step  14.
  9. Check for an open or high resistance in Black wire between blower motor relay and chassis ground G117. Repair Black wire as necessary, then go to step  24. If circuit is okay, go to step  15.
  10. Turn ignition off. Disconnect blower motor relay. Turn ignition on. Using a test light connected to ground, probe blower motor supply voltage circuit between the blower motor relay and the blower motor resistor. Place blower motor switch in minimum, medium (1), and medium (2) speed positions. If test light illuminates in each speed position, go to step  15. If test light does not illuminate in each speed position, go to next step.
  11. Check for an open, short to ground or high resistance in blower motor supply voltage circuit. Repair as necessary, then go to step  24. If circuit is okay, go to next step.
  12. Turn ignition off. Disconnect blower motor resistor. Turn ignition on. Place mode control in vent position. Using a test light connected to ground, probe the low, medium (1), and medium (2) blower motor control circuits. Place blower motor switch in appropriate speed position for circuit being tested. If test light illuminates when blower motor switch in is each position, go to step  17. If test light does not illuminate when blower motor switch in is each position, go to next step.
  13. Check for an open or high resistance in suspect blower motor control circuit of blower motor resistor. Repair circuit as necessary, then go to step 24. If circuit is okay, go to step  18.
  14. Check for an open or high resistance in low blower motor control circuit. Repair as necessary, then go to step  24. If circuit is okay, go to step  18.
  15. Check blower motor relay for loose wires and/or poor connections. Repair as necessary, then go to step  24. If wiring and connections are okay, go to step  20.
  16. Check blower motor for loose wires and/or poor connections. Repair as necessary, then go to step  24. If wiring and connections are okay, go to step  21.
  17. Check blower motor resistor harness connector for loose wires and/or poor connections. Repair as necessary, then go to step  24. If wiring and connections are okay, go to step  22.
  18. Check HVAC control assembly harness connector for loose wires and/or poor connections. Repair as necessary, then go to step  24. If wiring and connections are okay, go to step  23.
  19. Repair battery voltage circuit of blower motor relay. After repairs are complete, go to step  24.
  20. Replace blower motor relay. See BLOWER MOTOR RELAY  under REMOVAL & INSTALLATION. After replacement, go to step  24.
  21. Replace blower motor. See BLOWER MOTOR  under REMOVAL & INSTALLATION. After replacement, go to step  24.
  22. Replace blower motor resistor. See BLOWER MOTOR RESISTOR  under REMOVAL & INSTALLATION. After replacement, go to step  24.
  23. Replace HVAC control assembly. See HVAC CONTROL ASSEMBLY  under REMOVAL & INSTALLATION. After replacement, go to next step.
  24. Operate system to verify repair. If system does not operate properly, go to step  3. If system operates correctly, test is complete.
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