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Dan
Dan, Auto Technician
Category: Chevy
Satisfied Customers: 3490
Experience:  GM Mark of Excellence/ Service Guild Participant with 13 years experience, ASE Master Certified
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98 S10 pickup Heater core replacement - 4 cyl, 2wheel drive

Resolved Question:

Im in the process of replacing the heater core in my S10 P/U. Ive read the question/answer with "Bob" from sept. and its really saved my $%%, But Ive gotten I think all the bolts that were listed before but am still unable to get the HVAC unit to come out. It wiggles but seems to still be attached at the bottom bolt (from inside) and Ive removed the nuts from studs going from the engine side. I have the bolt from under the resistor out too.

What could I have missed?
Submitted: 6 years ago.
Category: Chevy
Expert:  Dan replied 6 years ago.

Heater/Vent Module Replacement

Removal Procedure

    Object Number: 617612  Size: SH
    Click here for detailed picture of above imageidth=
  1. Remove the instrument panel. Refer to Instrument Panel (I/P) Carrier Replacement in Instrument Panel, Gages and Console.
  2. Drain the engine coolant. Refer to Draining and Filling Cooling System in Engine Cooling.
  3. On vehicles with automatic climate control only, cut the outer layer of the A/C evaporator and blower module in order to access the service access cover.
    Object Number: 617623  Size: SH
    Click here for detailed picture of above imageidth=
  4. On vehicles with automatic climate control only, remove the service access cover mounting screws (1).
  5. On vehicles with automatic climate control only, remove the service access cover (2).
  6. On vehicles without automatic climate control, remove the blower motor resistor. Refer to Blower Motor Resistor Replacement .

    Important: Mark and use the same mounting bolt for the heater/vent module during the installation process. Other mounting bolts are longer and will obstruct the operation of the temperature door.

  7. Remove the heat/vent module mounting bolt through the blower motor resistor or service access cover opening.
    Object Number: 1595  Size: SH
    Click here for detailed picture of above imageidth=
  8. On vehicles with A/C only, remove the right wheel house panel. Refer to Wheelhouse Panel Replacement in Body Front End.
  9. On vehicles with A/C only, raise and support vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
  10. On vehicles with A/C only, remove the front right tire. Refer to Tire and Wheel Removal and Installation in Tires and Wheels.
  11. On the Utility only, remove the A/C evaporator and blower module heat shield screws.
  12. On the Utility only, slide the A/C evaporator and blower module heat shield toward the front of the vehicle.
  13. Remove the 2 lower heat/vent module mounting nuts.
  14. On the Utility only, remove the A/C evaporator and blower module heat shield bracket.
  15. Remove the bottom right heat/vent module mounting bolt from inside the vehicle.

    Important: The heat/vent mounting stud has a flange on the inside and cannot be removed from under the hood. Stop turning the stud after the threads are off the heat/vent module.

  16. On the Utility only, while an assistant inside the vehicle pulls the bottom right corner of the heat/vent module approximately 2.5 mm (1 in) back, remove the 2 heat/vent module mounting studs.
  17. On vehicles with A/C only, lower the vehicle.
    Object Number: 529580  Size: SH
    Click here for detailed picture of above imageidth=
  18. On vehicles with a 2.2 L engine only, remove the engine wiring harness bracket located at the rear of the intake manifold. Refer to Valve Rocker Arm Cover Replacement in Engine Mechanical - 2.2 L.
  19. Remove the HVAC module mounting bolt located at the lower left side of the heater core to heater hose connection.
  20. Remove the HVAC module mounting nut located at the lower right side of the heater core to heater connection.

    Important: The heat/vent mounting stud has a flange on the inside and cannot be removed from under the hood. Stop turning the stud after the threads are off the heat/vent module.

  21. On the Utility only, loosen the HVAC module mounting studs until the threads are free from the heat/vent module.
  22. Disconnect all of the electrical connectors from the HVAC module.
  23. Disconnect all of the vacuum lines from the heater assembly.
  24. Disconnect the heater hoses from the heater core.
  25. Remove the HVAC module from the vehicle.
Installation Procedure

    Object Number: 529580  Size: SH
    Click here for detailed picture of above imageidth=
  1. If replacing the HVAC module, transfer the components from the old heat/vent module as necessary.

    Important: Before installing the HVAC module to the vehicle, ensure that the HVAC module mounting studs are located in the proper positions.

  2. Install the HVAC module to the vehicle.
  3. Connect the heater hoses to the heater core.
  4. Connect all of the vacuum lines to the heater assembly.
  5. Connect all of the electrical connectors to the HVAC module.
  6. Install the bottom right HVAC module mounting bolt from inside the vehicle approximately halfway into the threads.

    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.

  7. On the Utility only, install the HVAC module mounting stud located at the lower right side of the heater core to heater hoses connection in the engine compartment.

    Tighten
    Tighten the HVAC module mounting stud to 4.5 N·m (40 lb in).

  8. On vehicles with A/C only, raise the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
  9. On the Utility only, install the bottom right HVAC mounting studs. Ask an assistant to pull the bottom right corner of the HVAC module back from inside the vehicle.

    Tighten
    Tighten the heat/vent module mounting studs to 4.5 N·m (40 lb in).

  10. On the Utility only, install the A/C evaporator and blower module heat shield bracket.
  11. Install the heater/vent module mounting nuts.

    Tighten
    Tighten the HVAC module mounting nuts to 4.5 N·m (40 lb in).

  12. On the Utility only, slide the A/C evaporator and blower module heat shield into the original position.
  13. On the Utility only, install the A/C evaporator and blower module heat shield screws.

    Tighten
    Tighten the A/C evaporator and blower module heat shield screws 2.2 N·m (19 lb in).


    Object Number: 1595  Size: SH
    Click here for detailed picture of above imageidth=
  14. On vehicles with A/C only, install the right front tire. Refer to Tire and Wheel Removal and Installation in Tires and Wheels.
  15. On vehicles with A/C only, lower the vehicle.
  16. Install the bottom right HVAC module mounting bolt from inside the vehicle.

    Tighten
    Tighten the HVAC module mounting bolt to 4.5 N·m (40 lb in).

  17. On vehicles with A/C only, install the right wheel house panel. Refer to Wheelhouse Panel Replacement in Body Front End.
    Object Number: 529580  Size: SH
    Click here for detailed picture of above imageidth=
  18. Install the HVAC module mounting nut located at the lower right side of the heater core to heater connection.

    Tighten
    Tighten the HVAC module mounting nut to 4.5 N·m (40 lb in).

  19. Install the HVAC module mounting bolt located at the lower left side of the heater core to heater hose connection.

    Tighten
    Tighten the HVAC module mounting bolt to 4.5 N·m (40 lb in).

  20. On vehicles with the 2.2 L engine only, install the engine wiring harness bracket located at the rear of the intake manifold. Refer to Valve Rocker Arm Cover Replacement in Engine Mechanical - 2.2 L.

    Important: Use the same mounting bolt marked during removal for the HVAC module during the installation process. Other mounting bolts are longer and will obstruct the operation of the temperature door.

  21. Install the HVAC module mounting bolt through the blower motor resistor or service access cover opening.

    Tighten
    Tighten the HVAC module mounting bolt to 4.5 N·m (40 lb in).

  22. On vehicles without automatic climate control, install the blower motor resistor. Refer to Blower Motor Resistor Replacement .
    Object Number: 617623  Size: SH
    Click here for detailed picture of above imageidth=
  23. On vehicles with automatic climate control only, install the service access cover (2).
  24. On vehicles with automatic climate control only, install the service access cover mounting screws (1).

    Tighten
    Tighten the screws to 1.9 N·m (17 lb in).


    Object Number: 617612  Size: SH
    Click here for detailed picture of above imageidth=
  25. On vehicles with automatic climate control only, install the outer layer of the A/C evaporator and blower module.

    Important: Do not use RTV. Apply the adhesive bead as straight as possible. Allow the adhesive to set for 15 minutes or until the adhesive becomes tacky.

  26. Seal the cut line using black weather-strip adhesive.
  27. Refill the engine coolant. Refer to Draining and Filling Cooling System in Engine Cooling.
  28. Install the instrument panel. Refer to Instrument Panel (I/P) Carrier Replacement in Instrument Panel, Gages and Console.
  29. Calibrate the HVAC module actuator.
  30. Heater Core Replacement

    Removal Procedure
    1. Remove the heater/vent module. Refer to Heater/Vent Module Replacement .
      Object Number: 426946  Size: SH
      Click here for detailed picture of above imageidth=
    2. Remove the heater core access cover screws.
    3. Remove the heater core access cover.
      Object Number: 426950  Size: SH
      Click here for detailed picture of above imageidth=
    4. Remove the heater core from the heater/vent module.
    Installation Procedure

      Object Number: 426950  Size: SH
      Click here for detailed picture of above imageidth=
    1. Install the heater core to the heater/vent module.
      Object Number: 426946  Size: SH
      Click here for detailed picture of above imageidth=

      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.

    2. Install the heater core access cover.

      Tighten
      Tighten the heater core access cover screws to 1.9 N·m (17 lb in).

    3. Install the heater/vent module. Refer to Heater/Vent Module Replacement .

Dan, Auto Technician
Category: Chevy
Satisfied Customers: 3490
Experience: GM Mark of Excellence/ Service Guild Participant with 13 years experience, ASE Master Certified
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