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Matt J
Matt J, Chevy Technician
Category: Chevy
Satisfied Customers: 1399
Experience:  10+ years automotive tech, 5 years of experience in a GM dealer
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how to replace a heater core on a 99 chevy silverado

Customer Question

how to replace a heater core on a 99 chevy silverado
Submitted: 5 years ago.
Category: Chevy
Expert:  Matt J replied 5 years ago.

 

Heater Core Replacement

Removal Procedure

Caution: Unless directed otherwise, the ignition and start switch must be in the OFF or LOCK position, and all electrical loads must be OFF before servicing any electrical component. Disconnect the negative battery cable to prevent an electrical spark should a tool or equipment come in contact with an exposed electrical terminal. Failure to follow these precautions may result in personal injury and/or damage to the vehicle or its components.

  1. Disconnect the negative battery cable.
  2. Drain the engine coolant.
  3. Disconnect the heater hoses.
  4. Remove the instrument panel (IP) bezel.
  5. Remove the radio.
  6. Remove the heater control assembly.
  7. Disconnect the temperature control cable from the heater/ventilation module.
  8. Disconnect the temperature control cable from the heater/ventilation module.
  9. Remove the temperature control cable from the IP carrier.
  10. Disconnect the mode control cable from the heater/ventilation module.
  11. Remove the instrument panel (IP) carrier. Refer to Instrument Panel (I/P) Carrier Replacement in Instrument Panel, Gauges and Console.

Instrument Panel Carrier Replacement

Removal Procedure

    Caution: Unless directed otherwise, the ignition and start switch must be in the OFF or LOCK position, and all electrical loads must be OFF before servicing any electrical component. Disconnect the negative battery cable to prevent an electrical spark should a tool or equipment come in contact with an exposed electrical terminal. Failure to follow these precautions may result in personal injury and/or damage to the vehicle or its components.

    Caution: This vehicle is equipped with a Supplemental Inflatable Restraint (SIR) System. Failure to follow the correct procedure could cause the following conditions:

    Air bag deployment
    Personal injury
    Unnecessary SIR system repairs
    In order to avoid the above conditions, observe the following guidelines:
    Refer to SIR Component Views in order to determine if you are performing service on or near the SIR components or the SIR wiring.
    If you are performing service on or near the SIR components or the SIR wiring, disable the SIR system. Refer to Disabling the SIR System.

     

  1. Disconnect the negative battery cable.
  2. Remove the I/P trim pad.
  3. Remove the center console, if equipped.
  4. Remove the driver side knee bolster.
  5. Remove the lower I/P trim panel.
  6. Remove the passenger side air bag module.
  7. Remove the accessory switch housing.
  8. Remove the left air louver housing.
  9. Remove the steering column.
  10. Remove the remote control door lock receiver module, if equipped.
    Object Number: 786370  Size: SH

  11. Remove the data link bolt.
  12. Remove the park brake release lever from the I/P.
  13. Remove the I/P cluster. .
  14. Remove both front window air duct from the I/P assembly.
  15. Remove the harness from the I/P.
    Object Number: 394655  Size: SH

  16. Remove the I/P assembly retaining bolts (3) and nuts (4).
  17. Remove all harness hold down retainers from the I/P assembly.
  18. Remove the I/P assembly from the vehicle.
    Object Number: 348641  Size: SH

  19. Remove the I/P upper brackets.
  20. Disconnect all the electrical connectors from the wiring harness junction block.
  21. Remove the transfer case control module from the bracket, if equipped.
  22. Remove the antenna cable from the cross car duct.
  23. Remove the cross car duct.
  24. Separate the I/P harness from the carrier.

    Do not remove the I/P harness from the vehicle.


    Object Number: 892882  Size: SH

  25. If replacing the HVAC module, remove the right side of the carrier from the vehicle to gain access to the module.
    Object Number: 540359  Size: SH

  26. Remove the I/P center support bracket bezel (1).
    Object Number: 397332  Size: SH

    Important: Remove all of the parts of the I/P carrier assembly from the vehicle as a unit.

  27. Remove the I/P center support bracket bolt.
    Object Number: 397335  Size: SH

  28. Remove the I/P carrier side bolts.

    The left side is shown, the right side is similar.


    Object Number: 397334  Size: SH

  29. Remove the I/P carrier top bolts (1).
    Object Number: 499360  Size: SH

  30. Remove the I/P carrier (1) from the vehicle.

Object Number: 372310  Size: SH

  • Disconnect the electrical harnesses and the ground connections as necessary.
    Object Number: 363009  Size: SH

  • Remove the heater/ventilation module mounting nuts and the screws.
  • Remove the heater/ventilation module assembly. Set the module assembly on a bench.
  • Remove the heater core cover screws.
    Object Number: 363771  Size: SH

  • Remove the heater core cover.
    Object Number: 363772  Size: SH

  • Remove the heater core.
  •  

    Object Number: 363772  Size: SH

  • Install the heater core.
    Object Number: 363771  Size: SH

  • Install the heater core cover.

    Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  • Install heater core cover screws.

    Tighten
    Tighten the screws to 1.6 N·m (14 lb in).

  • Install the heater/ventilation module assembly to the vehicle.
  • Install the heater/ventilation module mounting nuts and the screws.

    Tighten

    Tighten the screws to 4 N·m (35 lb in).
    Tighten the nuts to 9 N·m (80 lb in).

    Object Number: 372310  Size: SH

  • Connect the electrical harnesses and the ground connections as necessary.
  • Install the instrument panel carrier.

    1. Object Number: 499360  Size: SH

    2. Position the I/P carrier (1) in the vehicle.

      Notice: Refer to Fastener Notice in Cautions and Notices.


      Object Number: 397334  Size: SH

    3. Install the I/P carrier top bolts (1).

      Tighten

      Tighten the bolts to 50 N·m (37 lb ft).


      Object Number: 397335  Size: SH

    4. Install the I/P carrier side bolts.

      The left side is shown, the right is similar.

      Tighten

      Tighten the bolts to 50 N·m (37 lb ft).


      Object Number: 397332  Size: SH

    5. Install the I/P center support bracket bolt.

      Tighten

      Tighten the bolt to 25 N·m (18 lb ft).


      Object Number: 540359  Size: SH

    6. Install the I/P center support bracket bezel (1).
      Object Number: 892882  Size: SH

    7. Install the right side of the carrier to the vehicle, if the HVAC module was removed.
    8. Install the retaining bolts.

      Tighten

      Tighten bolts to 50 N·m (37 lb ft).

    9. Attach the I/P harness to the carrier.
    10. Install the cross car duct. Ventilation and Air Conditioning
    11. Install the antenna cable to the cross car duct.
    12. Install the transfer case control module to the bracket, if equipped.
    13. Connect all of the electrical connectors to the wiring harness junction block.Object Number: 348641  Size: SH

    14. Install the I/P upper brackets.

      Tighten

      Tighten the retaining bolts to 2 N·m (18 lb in)

    15. Install the I/P assembly to the vehicle.
      Object Number: 394655  Size: SH

    16. Install the I/P assembly retaining nuts and bolts.

      Ensure the wire harness is routed to all of the openings.

      Tighten

      Tighten the retaining bolts and nuts to 9 N·m (80 lb in).

    17. Install the harness hold down retainers to the I/P assembly.
    18. Install the harness to the I/P.
    19. Install both front window air duct to the I/P assembly.
    20. Install the I/P cluster assembly.
    21. Install the park brake release lever to the I/P.
      Object Number: 786370  Size: SH

    22. Install the data link connector bolt.

      Tighten

      Tighten the retaining bolts to 6 N·m (53 lb in)

    23. Install the remote control door lock receiver module, if equipped.
    24. Install the steering column.
    25. Install the left air louver housing.
    26. Install the accessory switch housing.
    27. Install the HVAC control.
    28. Install the radio.
    29. Install the passenger side airbag module.
    30. Install the lower trim panel.
    31. Install the driver side knee bolster.
    32. Install the center console, if equipped.
    33. Install the I/P trim pad.
    34. Connect the mode control cable to the heater/ventilation module.
    35. Connect the temperature control cable to the heater/ventilation module.
    36. Connect the heater hoses.
    37. Refill the engine coolant.
    38. Connect the negative battery cable.

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