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HOMESERVICE MANUALSGMC1999FORWARD CONTROL 5.7 R, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 718 (HEATING, VENTILATION & AIR CONDITIONING)REPAIR INSTRUCTIONSHVAC MODULE ASSEMBLY REPLACEMENTREMOVAL PROCEDURE
1999 GMC Forward Control 5.7 R, Automatic

Removal Procedure

1999 GMC Forward Control 5.7 R, AutomaticSECTION Removal Procedure
WARNING: This page is about a different car, the 2002 Pontiac Grand Prix. However, it is still accessible from the selected car via links, so may be relevant.
  1. Recover the refrigerant. Refer to Refrigerant Recovery and Recharging .
  2. Disconnect the battery negative cable. Refer to BATTERY NEGATIVE CABLE DISCONNECT/CONNECT PROCEDURE .
  3. Remove the air cleaner assembly. Refer to AIR CLEANER ASSEMBLY .
  4. Remove the fuel injector sight shield (3.8L only). Refer to FUEL INJECTOR SIGHT SHIELD REPLACEMENT (L36) or FUEL INJECTOR SIGHT SHIELD REPLACEMENT (L67) .
  5. Drain the cooling system. Refer to DRAINING AND FILLING COOLING SYSTEM .
  6. Remove the instrument panel (IP) trim pad. Refer to TRIM PAD REPLACEMENT -- IP .
  7. Remove the passenger side SIR inflator module. Refer to REMOVAL & INSTALLATION (PASSENGER-SIDE) .
  8. Remove the screw from the right and left side air distribution duct.
  9. Remove the right and left side air distribution duct.
    10. Fig 1: Right & Left Side Air Distribution Ducts & Screws
    G01672668Courtesy of GENERAL MOTORS CORP.
  10. Unclip the fuse block and position aside.
  11. Remove the two screws below the fuse block that hold the main harness connector to the cross vehicle beam.
  12. Remove the brake pedal. Refer to BRAKE PEDAL ASSEMBLY .
  13. Remove the bolts from the steering column support bracket and remove the bracket.
    Fig 2: Fuse Block
    G01672669Courtesy of GENERAL MOTORS CORP.
  14. Remove the retaining bolts and position the BCM bracket aside.
  15. Release the wiring harness retaining clips from the cross vehicle beam and position the wiring harness out of the way.
    Fig 3: BCM Bracket & Retaining Bolts
    G01672670Courtesy of GENERAL MOTORS CORP.
  16. Remove the retaining bolts from the center support bracket of the HVAC module.
  17. Remove the center support bracket of the HVAC module.
    Fig 4: Center Support Bracket & Retaining Bolts
    G01672671Courtesy of GENERAL MOTORS CORP.
  18. Remove the retaining bolts from the upper support brackets of the HVAC module.
    Fig 5: Upper Support Brackets & Retaining Bolts
    G01672672Courtesy of GENERAL MOTORS CORP.
  19. Remove the bolts which secure the left cross vehicle beam to the hinge pillar.
    Fig 6: Left Cross Vehicle Beam Hinge Pillar Bolts
    G01672673Courtesy of GENERAL MOTORS CORP.
  20. Remove the bolts which secure the right cross vehicle beam to the hinge pillar.
    Fig 7: Right Cross Vehicle Beam Hinge Pillar Bolts
    G01672674Courtesy of GENERAL MOTORS CORP.
  21. Remove the bolt (1) from the cross vehicle beam.
  22. Remove the cross vehicle beam from the vehicle.
    Fig 8: Cross Vehicle Beam & Bolt
    G01672675Courtesy of GENERAL MOTORS CORP.
  23. Remove the accumulator tube to evaporator core block fitting bolt.
  24. Disconnect the accumulator tube from the evaporator.
  25. Disconnect the evaporator tube from the evaporator.
  26. Remove the O-rings seals and discard.
    Fig 9: Evaporator Core Block Fitting Bolt
    G01672676Courtesy of GENERAL MOTORS CORP.
  27. Use J 38185  in order to position aside the heater hose inlet and outlet clamps at the heater core (3.1 L).
  28. Disconnect the heater inlet and outlet hoses from the heater core (3.1 L).
    Fig 10: Inlet & Outlet Heater Hoses & Clamps (3.1L)
    G01672677Courtesy of GENERAL MOTORS CORP.
  29. Use J 38185  in order to position aside the heater hose inlet and outlet clamps at the heater core (3.8L).
  30. Disconnect the heater inlet and outlet hoses from the heater core (3.8L).
  31. Disconnect the vacuum hoses from the HVAC module assembly.
  32. Disconnect the electrical connectors from the HVAC module assembly.
    Fig 11: Inlet & Outlet Heater Hoses & Clamps (3.8L)
    G01672678Courtesy of GENERAL MOTORS CORP.

    Important:  Position the heater core outlet cover downward and rearward in order to disconnect the cover from the rear area floor duct assembly.

  33. Remove the cover screws from the heater core outlet.
  34. Remove the cover from the heater core outlet.
    Fig 12: Heater Core Outlet Cover
    G01672679Courtesy of GENERAL MOTORS CORP.
  35. Remove the evaporator drain elbow.
    Fig 13: Evaporator Drain Elbow
    G01672680Courtesy of GENERAL MOTORS CORP.
  36. Remove the nuts which secure the HVAC control module to the dash.
  37. Remove the HVAC control module.
    Fig 14: HVAC Control Module Securing Nuts
    G01672681Courtesy of GENERAL MOTORS CORP.
  38. Remove all of the seals (1,2,3) from the outer HVAC control module.
    Fig 15: Outer HVAC Control Module Seals
    G01672682Courtesy of GENERAL MOTORS CORP.
RENDER: 1.0x

NO RELATED

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When to See a Mechanic

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.