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Home >> GMC >> 2000 >> C3500 HD 6.5 F, Standard >> Repair and Diagnosis >> Heating, Ventilation & A/C (HVAC) >> HVAC Control Systems >> HVAC System - Manual - Escalade, Pickup, TAHOE & YUKON >> Trouble Shooting >> Auxiliary Blower Motor Inoperative At Low Speed

Auxiliary Blower Motor Inoperative At Low Speed

  1. Perform BLOWER CONTROLS SYSTEM CHECK . Go to next step.
  2. Remove auxiliary blower motor low 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 low 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 "C" and "E" of front and rear auxiliary A/C-heater control assemblies. Rotate blower switches to low position. If continuity is indicated at both switches, go to step  6. If continuity is not indicated at 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 auxiliary blower motor resistor terminals "B" and "C" (resistor side). 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 low 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 low 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 Dark Blue wire between auxiliary blower motor low speed relay cavity terminal No. 2 and terminal "C" of front and rear auxiliary A/C-heater control assembly connectors. Go to BLOWER CONTROLS SYSTEM CHECK .
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