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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 High Speed

Auxiliary Blower Motor Inoperative At High Speed

  1. Perform BLOWER CONTROLS SYSTEM CHECK . Go to next step.
  2. Remove auxiliary blower motor high speed relay. Relays are located on top of auxiliary heater unit, near right rear wheelwell. Connect a fused jumper 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 high speed relay. Go to BLOWER CONTROLS SYSTEM CHECK .
  4. Disconnect front auxiliary A/C-heater control assembly. Use a DVOM to check for continuity between terminals "B" and "D" of front auxiliary A/C-heater control assembly. Rotate switch to high position. Use a DVOM to check for continuity between terminals "B" and "F" of front auxiliary A/C-heater control assembly. Rotate switch to rear position. If continuity is indicated in both positions, go to step  6. If continuity is not indicated, go to next step.
  5. Replace front auxiliary A/C-heater control assembly. See AUXILIARY A/C-HEATER CONTROL ASSEMBLIES  under REMOVAL & INSTALLATION. Go to BLOWER CONTROLS SYSTEM CHECK .
  6. Disconnect rear auxiliary A/C-heater control assembly. Use a DVOM to check for continuity between terminals "F" and "D" of rear auxiliary A/C-heater control assembly. Rotate switch to high position. If continuity is indicated, go to step  8. If continuity is not indicated, go to next step.
  7. Replace rear auxiliary A/C-heater control assembly. See AUXILIARY A/C-HEATER CONTROL ASSEMBLIES  under REMOVAL & INSTALLATION. Go to BLOWER CONTROLS SYSTEM CHECK .
  8. Disconnect auxiliary blower motor connector. Use a DVOM to check for continuity between auxiliary blower motor high speed relay cavity terminal No. 4 and auxiliary blower motor connector terminal "A" (Yellow wire). If continuity is indicated, go to step  10. If continuity is not indicated, go to next step .
  9. Repair open in Yellow wire between auxiliary blower motor high speed relay and auxiliary blower motor. Go to BLOWER CONTROLS SYSTEM CHECK .
  10. Use a DVOM to measure voltage between auxiliary blower motor high speed relay cavity terminal No. 1 (Red wire) and ground. If battery voltage is indicated, go to step  12. If battery voltage is not indicated, go to next step.
  11. Repair open in Red wire between auxiliary blower motor high speed relay and splice S401. Splice S401 is located approximately 5" (13 cm) from auxiliary blower motor connector. Go to BLOWER CONTROLS SYSTEM CHECK .
  12. Repair open in White wire between auxiliary blower motor high speed relay cavity terminal No. 2 and front auxiliary A/C-heater control assembly connector terminal "D". Go to BLOWER CONTROLS SYSTEM CHECK .
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