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HOMESERVICE MANUALSGMC1999FORWARD CONTROL 5.7 R, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 30 (HVAC SYSTEMS - AUTOMATIC)SYMPTOM TESTSTEST C: AIR RECIRCULATION MALFUNCTION
1999 GMC Forward Control 5.7 R, Automatic

Test C: Air RECIRCULATION Malfunction

1999 GMC Forward Control 5.7 R, AutomaticSECTION Test C: Air RECIRCULATION Malfunction
WARNING: This page is about a different car, the 2002 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.
  1. Perform diagnostic system check. See DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing System Check, go to next step.
  2. Connect scan tool. Turn ignition on, engine off. Using scan tool, perform RECALIBRATE ALL MOTORS command in INSTRUMENT PANEL MODULE SPECIAL FUNCTIONS. Observe current DTC list in Instrument Panel Module (IPM). If scan tool displays any DTCs, see DIAGNOSTIC TROUBLE CODE INDEX  table under SELF-DIAGNOSTIC SYSTEM. If scan tool did not display any DTCs, go to next step.
  3. Turn ignition ON, engine OFF. Place blower motor switch in highest speed position. Place mode switch in bi-level position. Move recirculation switch between recirculation and ambient air positions. If recirculation door moves from recirculation to outside air positions, test for intermittent loose wires and/or poor connections between recirculation actuator and IPM. See INTERMITTENTS  under TROUBLE SHOOTING. If recirculation door does not move from recirculation to outside air positions, go to next step. See Figure.
  4. Use scan tool to observe AIR INLET DOOR COMMAND parameter in IPM data list. Alternatively place recirculation switch in recirculation and ambient air positions. If scan tool indicates that AIR INLET DOOR COMMAND parameter changes for each change in selected position, go to step  6. If scan tool indicates that AIR INLET DOOR COMMAND parameter does not change for each change in selected position, go to next step.
  5. Use scan tool to perform COMMAND RECIRCULATION DOOR from OUTSIDE to RECIRC. Observe AIR OUTLET DOOR COMMANDED parameter. If scan tool indicates that AIR INLET COMMANDED changes, go to step  11. If scan tool indicates that AIR INLET COMMANDED does not change, go to step  10.
  6. Check Brown wire between HVAC fuse (10-amp) and terminal No. 5 of Recirculation Actuator harness connector for high resistance. See Fig 1. If high resistance condition is found, repair as necessary. Go to step  15. If high resistance condition is not found, go to next step.
  7. Inspect air distribution system for a dirty HVAC air filter (if equipped), misaligned air ducts, air leaks or any obstructions to airflow. SeePASSENGER COMPARTMENT AIR FILTER  under REMOVAL & INSTALLATION. Repair any problems found. Go to step  15. If no problems were found, go to next step.
  8. Inspect Recirculation Door and Actuator for misaligned Recirculation Actuator, broken recirculation door or binding linkages, an obstruction that prevents Recirculation Door from moving with in its full range of motion or misaligned or missing Recirculation Door seals. See Figure. Repair any problems found. Go to step  15. If no problems found, go to next step.
    Fig 1: Identifying Recirculation Actuator Harness Connectors
    G00056191Courtesy of GENERAL MOTORS CORP.
  9. Check for loose wires and/or poor connections to Recirculation Actuator harness connector. Repair any poor connections found. Go to step  15. If poor connections are not found, go to step  12.
  10. Check for loose wires and/or poor connections at HVAC Control Module harness connector. Repair any poor connections found. Go to step  15. If poor connections are not found, go to step  13.
  11. Check for loose wires and/or poor connections at IPM harness connectors. Repair any poor connections found. Go to step  15. If poor connections are not found, go to step  14.
  12. Replace Recirculation Actuator. See RECIRCULATION ACTUATOR  under REMOVAL & INSTALLATION. Go to step  15.
  13. Replace HVAC Control Module. See HVAC CONTROL MODULE  under REMOVAL & INSTALLATION. Go to step  15.
  14. Replace IPM. See INSTRUMENT PANEL MODULE (IPM)  under REMOVAL & INSTALLATION. Go to step  15.
  15. Operate system to verify repair. If condition is corrected, system is okay. If condition is not corrected, go to step  3.
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Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.