GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1997 🢒 Corvette 🢒 HVAC 🢒 HVAC Systems - Manual 🢒 Heater/Evaporator Module Assembly

Removal Procedure
  1. Disconnect the negative battery cable from the battery. Refer to

    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.

    in General Information.
  2. Disable the SIR system. Refer to Disabling the SIR System in SIR.
  3. Recover the refrigerant from the air conditioning system.
  4. Drain the cooling system. Refer to Cooling System Draining and Filling in Engine Cooling.
  5. Remove the intake manifold. Refer to Intake Manifold Replacement in Engine Mechanical.

    6. Object Number: 82061 Size: SH
  6. Disconnect the heater hose pipe assembly from the module.

    7. Object Number: 82081 Size: SH
  7. Disconnect the accumulator hose assembly from the module.

    8. Object Number: 174403 Size: SH
  8. Remove the drain tube from the module.
  9. Remove the I/P upper pad and air distribution duct assembly. Refer to Instrument Panel Upper Trim Pad Replacement in Instrument Panel, Gages and Console.
  10. Disconnect the electrical connector from the instrument cluster.
  11. Remove the instrument cluster assembly. Refer to Instrument Cluster Replacement in Instrument Panel, Gages and Console.

    12. Object Number: 95655 Size: SH
  12. Remove the LH inboard side window glass defroster duct from the windshield defroster duct.

    13. Object Number: 95658 Size: SH
  13. Remove the RH inboard side window glass defroster duct from the windshield defroster duct.

    14. Object Number: 179744 Size: SH
  14. Disconnect the DRL electrical connector, if equipped, from the windshield defroster duct.

    15. Object Number: 179747 Size: SH
  15. Disconnect the sun load temperature sensor (2), if equipped, from the windshield defroster duct.

    16. Object Number: 179743 Size: SH
  16. Remove the windshield defroster duct from the module.

    17. Object Number: 179226 Size: SH
  17. Remove the inside air temperature sensor duct from the module.
  18. Disconnect the electrical connector from the passenger SIR module.
  19. Remove the passenger SIR bracket and module assembly. Refer to Instrument Panel Inflatable Restraint Module Bracket Replacement in Instrument Panel, Gages and Console.
  20. Remove the I/P center support bracket. Refer to Instrument Panel Center Support Bracket Replacement in Instrument Panel, Gages and Console.

    21. Object Number: 179748 Size: SH
  21. Disconnect the electrical (1) and vacuum (C60 only) connections (2) from the HVAC control head.
  22. Remove the driver's knee bolster. Refer to Knee Bolster Bracket Replacement in Instrument Panel, Gages and Console.
  23. Remove the I/P center support bracket. Refer to Instrument Panel Center Support Bracket Replacement in Instrument Panel, Gages and Console.
  24. Remove the driver's floor hush panel.

    25. Object Number: 179746 Size: SH
  25. Remove the LH floor air outlet duct from the module.
  26. Remove the passenger floor hush panel.

    27. Object Number: 95649 Size: SH
  27. Unsnap the lower RH floor air duct from the upper RH air duct.

    28. Object Number: 179750 Size: SH
  28. Remove the upper RH floor air duct from the module.

    29. Object Number: 179747 Size: SH

    Caution: Unplug the blower motor before removal. Blower motor case contact with any ground may start the fan and cause personal injury.

  29. Disconnect the electrical connector (5) from the blower motor.
  30. Remove the blower motor from the module. Refer to Blower Motor and Fan Assembly .
  31. Disconnect the electrical connector (1) from the temperature door control motor if equipped with (CJ2) .
  32. Disconnect the electrical connection to the vacuum solenoid (3) if equipped with (CJ2) .
  33. Disconnect the vacuum source line connection (4) from the I/P harness.

    34. Object Number: 179744 Size: SH
  34. Disconnect the electrical connector (2) from the temperature door control motor (C60).

    35. Object Number: 179749 Size: SH
  35. Remove the LH and RH rear floor air ducts from the module.

    36. Object Number: 175438 Size: SH
  36. Remove the bolts and nuts retaining the evaporator and heater core module to the bulkhead and I/P brace.
  37. Remove the evaporator and heater core module from the vehicle.

    38. Object Number: 179036 Size: SH
  38. Remove and discard the air inlet, drain, and plumbing seals.

Installation Procedure

    Object Number: 179036 Size: SH
  1. Install new air inlet, drain, and plumbing seals onto the HVAC module.

    2. Important: Align the cut-outs on the dashmat so that the air inlet, drain, and plumbing seals are sealed against the dash panel and not the dashmat.


    Object Number: 175438 Size: SH
  2. Install the HVAC module into the vehicle in the following order:
    3. 2.1. Insert the LH stud through the dash panel.
    2.2. Insert the drain tube through the dash panel.
    2.3. Insert the RH stud through the dash panel.
  3. Install the HVAC module mounting bracket bolts in the following order:
    4. 3.1. Install the LH mounting bracket bolt.
    3.2. Install the RH mounting bracket bolt.
    3.3. Tighten the LH and RH mounting bracket bolts.

    Tighten
    Tighten the HVAC module mounting bolts to 10 N·m (89 lb in).

    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.

    Important: To prevent possible water leaks or wind/road noise from entering the vehicle do not reuse the old HVAC module seal nuts.

  4. Install new seal nuts on the HVAC module studs.

    5. Tighten
    Tighten the HVAC module seal nuts to 10 N·m (89 lb in).

    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.


    Object Number: 179744 Size: SH
  5. Connect the electrical connector (2) to temperature door control motor (C60).

    6. Object Number: 179747 Size: SH
  6. Connect the vacuum source line (4) connection to the I/P harness.
  7. Connect the electrical connector to the vacuum solenoid (3) if equipped with (CJ2).
  8. Connect the electrical connector (1) to the temperature door control motor if equipped with (CJ2).
  9. Install the blower motor onto the module.

    10. Tighten
    Tighten the blower motor mounting screws to 20 N·m (15 lb in).

  10. Connect the blower motor electrical connector (5).

    11. Object Number: 179750 Size: SH
  11. Install the upper RH floor air outlet duct onto the module.

    12. Tighten
    Tighten the upper RH floor air outlet duct screws to 1.6 N·m (14 lb in).


    Object Number: 95649 Size: SH
  12. Snap the lower RH floor air outlet duct onto the upper RH floor air outlet duct.

    13. Object Number: 95733 Size: SH
  13. Install the RH upper rear floor air duct into RH lower rear floor air outlet duct.

    14. Object Number: 179749 Size: SH
  14. Install the LH and RH rear floor air outlet ducts into the HVAC module.
  15. Install the passenger floor hush panel.

    16. Object Number: 179746 Size: SH
  16. Install the LH floor air outlet duct onto the module.

    17. Tighten
    Tighten the LH floor air outlet duct screws to 1.6 N·m (14 lb in).

  17. Install the driver's floor hush panel.

    18. Object Number: 179744 Size: SH
  18. Connect the electrical connector (2) to the temperature door control motor (C60).

    19. Object Number: 179748 Size: SH
  19. Route the wiring for center stack back up between lower I/P brace and HVAC module.
  20. Connect the electrical (1) and vacuum (C60 only) connectors (2) the HVAC control head.
  21. Install the I/P center support bracket. Refer to Instrument Panel Center Support Bracket Replacement in Instrument Panel, Gages and Console.
  22. Install the driver's knee bolster. Refer to Knee Bolster Bracket Replacement in Instrument Panel, Gages and Console.

    23. Object Number: 179743 Size: SH
  23. Install the windshield defroster duct to the module.
    24. 23.1. Install the LH screw.
    23.2. Install the RH screw.

    Tighten
    Tighten the windshield defroster duct screws to 10 N·m (89 lb in).


    Object Number: 179747 Size: SH
  24. Connect the sun load temperature sensor electrical connector (2), if equipped, to the windshield defroster duct.

    25. Object Number: 179744 Size: SH
  25. Connect the DRL electrical connector (1), if equipped, to the windshield defroster duct.

    26. Object Number: 95658 Size: SH
  26. Install the RH inboard side window glass defroster duct onto the windshield defroster duct.
  27. Install the passenger SIR bracket and module assembly. Refer to Instrument Panel Inflatable Restraint Module Bracket Replacement in Instrument Panel, Gages and Console.

    28. Object Number: 95655 Size: SH
  28. Install the LH inboard side window glass defroster duct onto the windshield defroster duct.

    29. Object Number: 179226 Size: SH
  29. Install the inside air temperature sensor duct to the module.
  30. Connect the electrical connector to the instrument cluster.
  31. Install the instrument cluster Instrument Cluster Replacement in Instrument Panel, Gages and Console.
  32. Install the I/P upper pad and air distribution duct assembly. Refer to Instrument Panel Upper Trim Pad Replacement in Instrument Panel, Gages and Console.

    33. Object Number: 174403 Size: SH

    Important: The arrow on the drain tube indicates correct orientation. Make sure that the drain tube is fully seated.

  33. Install the drain tube to the module.

    34. Object Number: 82081 Size: SH
  34. Connect the accumulator hose assembly to the evaporator and heater core module.

    35. Tighten
    Tighten the accumulator hose mounting bolt to 16 N·m (12 lb in).


    Object Number: 82061 Size: SH
  35. Connect the heater hose pipe assembly to the evaporator and heater core module.

    36. Tighten

        • Tighten the heater hose pipe mounting bolt to 16 N·m (12 lb ft).
        • Tighten the heater hose mounting nut to 10 N·m (89 lb in).
  36. Install the intake manifold. Refer to Intake Manifold Replacement in Engine Mechanical.
  37. Connect the negative battery cable. Refer to

    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.

    in General Information.
  38. Enable the SIR system. Refer to Enabling the SIR System in SIR.
  39. Refill the cooling system. Refer to Cooling System Draining and Filling in Engine Cooling.
  40. Evacuate and charge the air conditioning system.