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Test D: Blower Motor Malfunction

WARNING: This page is about a different car, the 2002 Oldsmobile Intrigue. 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 blower motor is inoperative in all speed positions.
  1. If diagnostic system check was not performed, go to DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. If diagnostic system check was performed, go to next step.
  2. Turn ignition on. Place blower motor switch in each speed position. If blower motor operates at desired speeds, check for intermittents. If blower motor does not operate at desired speeds, go to next step.
  3. Using scan tool, observe DESIRED BLOWER MTR SPEED parameter in heating and air conditioning data list. Gradually adjust blower motor switch from minimum speed position to maximum speed position. If scan tool indicates DESIRED BLOWER MTR SPEED parameter continuously increases within 15-111 counts, go to next step. If DESIRED BLOWER MTR SPEED parameter does not continuously increase within 15-111 counts, go to step  10.
  4. Turn ignition off. Disconnect blower motor connector. Turn ignition on. Connect test light between blower motor supply voltage circuit and blower motor control circuit. See WIRING DIAGRAMS . Adjust blower motor switch from minimum speed position to maximum speed position. If test light comes on and increases intensity, go to step  8. If test light does not come on and increase intensity, go to next step.
  5. Check battery positive voltage circuit and ground circuit of blower motor control processor for high resistance. Repair wiring as necessary. If wiring is okay, go to next step.
  6. Ensure blower motor control processor and HVAC control module connectors are connected. Backprobe and measure voltage between blower speed control circuit at HVAC control module and ground. Gradually adjust blower motor switch from minimum speed to maximum speed. If voltage continuously decreases between 4.7-1.0 volts, go to step  9. If voltage does not continuously decreases between 4.7-1.0 volts, go to next step.
  7. Turn ignition off. Disconnect HVAC control module. Turn ignition on. Measure voltage between blower speed control circuit of HVAC control module and ground. If voltage is about 5 volts, go to step  9. If voltage is not about 5 volts, go to step  10.
  8. Check for poor connection at harness connector of blower motor. Repair connection as necessary. If connection is okay, go to step  11.
  9. Check for poor connection at harness connector of blower motor control processor. Repair connection as necessary. If connection is okay, go to step  12.
  10. Check for poor connection at harness connector of HVAC control module. Repair connector as necessary. If connector is okay, go to step  13.
  11. Replace blower motor. See BLOWER MOTOR  under REMOVAL & INSTALLATION. After repairs are complete, go to step  14.
  12. Replace blower motor control processor. See BLOWER MOTOR CONTROL MODULE PROCESSOR  under REMOVAL & INSTALLATION. After repairs are complete, go to step  14.
  13. Replace HVAC control module. See HVAC CONTROL MODULE  under REMOVAL & INSTALLATION. After repairs are complete, go to next step.
  14. 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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