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Auxiliary Blower Motor Inoperative At Medium Speed

NOTE: Auxiliary blower motor medium speed relay has two Red wires. Red wire, direct feed from convenience center, is hot at all times. The other Red wire is a switching wire to both auxiliary A/C-heater control assemblies.
  1. Perform BLOWER CONTROLS SYSTEM CHECK . Go to next step.
  2. Remove auxiliary blower motor medium speed relay. Relays are located on top of auxiliary heater unit, near right rear wheelwell. Connect a fused jumper wire between relay cavity terminals No. 1 (Red wire) and 4 (Yellow wire). See WIRING DIAGRAMS . If auxiliary blower motor runs, go to next step. If auxiliary blower motor does not run, go to step  4.
  3. Replace auxiliary blower motor medium speed relay. Go to BLOWER CONTROLS SYSTEM CHECK .
  4. Disconnect front and rear auxiliary A/C-heater control assemblies. Use a DVOM to check for continuity between terminals "B" and "E", and "B" and "F" of front auxiliary A/C-heater control assembly. Use a DVOM to check for continuity between terminals "E" and "F" of rear auxiliary A/C-heater control assembly. Rotate blower switches to medium position. If continuity is indicated for both switches, go to step  6. If continuity is not indicated at one or both switches, go to next step.
  5. Replace faulty auxiliary A/C-heater control assembly. See AUXILIARY A/C-HEATER CONTROL ASSEMBLIES  under REMOVAL & INSTALLATION. Go to BLOWER CONTROLS SYSTEM CHECK .
  6. Disconnect auxiliary blower resistor connector. Use a DVOM to check for continuity between terminals "A" (Light Blue wire) and "B" (Yellow wire). If continuity is indicated, go to step  8. If continuity is not indicated, go to next step.
  7. Replace auxiliary blower motor resistor. See AUXILIARY BLOWER MOTOR & FAN  under REMOVAL & INSTALLATION. Go to BLOWER CONTROLS SYSTEM CHECK .
  8. Use a DVOM to measure voltage between auxiliary blower motor medium speed relay cavity terminal No. 1 (Red wire) and ground. If battery voltage is indicated, go to step  10. If battery voltage is not indicated, go to next step.
  9. Repair open in Red wire between auxiliary blower motor medium speed relay and splice S401. Splice S401 is located approximately 5" (13 cm) from auxiliary blower motor connector. Go to BLOWER CONTROLS SYSTEM CHECK .
  10. Repair open in Red wire between auxiliary blower motor medium speed relay cavity terminal No. 2 and terminal "E" of front and rear auxiliary A/C-heater control assembly connectors. Go to BLOWER CONTROLS SYSTEM CHECK .
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