GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Oldsmobile 🢒 1998 🢒 Silhouette Ext. 🢒 HVAC 🢒 HVAC Systems - Manual 🢒 Auxiliary Air Conditioning Evaporator Thermal Expansion Valve Replacement

Removal Procedure
  1. Recover the refrigerant. Refer to Refrigerant Recovery and Recharging
  2. Raise and support vehicle. Refer to Lifting and Jacking the Vehicle in General Information.

    3. Object Number: 400659 Size: SH
  3. Remove the A/C line block fitting bolt.

    4. Important: Cap or tape the open A/C refrigerant lines immediately.

  4. Separate the line block fitting, remove and discard the O-ring seal, and cap or tape the A/C line to prevent contamination of the refrigerant system.
  5. Lower the vehicle.
  6. Remove the left side rear quarter trim. Refer to Rear Quarter Lower Trim Panel Replacement

    7. Object Number: 400644 Size: SH
  7. Remove the nut from the line block fitting at the thermal expansion valve.
  8. Carefully remove the A/C lines from the thermal expansion valve and pull the lines up through the floor of the vehicle.

    9. Important: Cap or tape the open A/C refrigerant lines immediately.

  9. Remove and discard the O-ring seals and cap or tape the lines to prevent contamination.

    10. Object Number: 400643 Size: SH
  10. Remove the bolts from the thermal expansion valve that were exposed by removal of the line block fitting.
  11. Remove the thermal expansion valve from the evaporator core lines.

    12. Important: Cap or tape the open A/C refrigerant lines immediately.

  12. Remove and discard the O-ring seals from the evaporation core lines. Cap or tape the lines to prevent contamination of the evaporator core.

Installation Procedure
  1. Remove the cap or tape from the evaporator lines.
  2. Using a lint-free clean, dry cloth, carefully clean the sealing surface of the evaporator lines and the thermal expansion valve.

    3. Object Number: 297228 Size: SH
  3. Lightly coat the new O-ring seal (1) with mineral base 525 viscosity refrigerant oil.

    4. Important: DO NOT allow any of the mineral base 525 viscosity refrigerant oil on the new O-ring seal to enter the refrigerant system.

  4. Carefully slide the new O-ring seal (1) onto the A/C line until seated.

    5. Allow a light coating of the refrigerant oil to remain on the A/C line in the area indicated (2) ONLY.


    Object Number: 400643 Size: SH
  5. Install the thermal expansion valve onto the evaporator core lines.

    6. 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.

  6. Install the bolts through the thermal expansion valve to the A/C line block fitting on the evaporator core lines.

    7. Tighten
    Tighten the bolts to 5 N·m ( 44 lb in).

  7. Remove the cap or tape from the A/C lines.
  8. Using a lint-free clean, dry cloth, carefully clean the sealing surface of the A/C lines and the thermal expansion valve.

    9. Object Number: 297228 Size: SH
  9. Lightly coat the new O-ring seal (1) with mineral base 525 viscosity refrigerant oil.

    10. Important: DO NOT allow any of the mineral base 525 viscosity refrigerant oil on the new O-ring seal to enter the refrigerant system.

  10. Carefully slide the new O-ring seal (1) onto the A/C line until seated.

    11. Allow a light coating of the refrigerant oil to remain on the A/C line in the area indicated (2) ONLY.


    Object Number: 400644 Size: SH
  11. Carefully install the A/C lines through the floor of the vehicle and then up to the thermal expansion valve.
  12. Install the retaining nut to the line block fitting on the A/C lines

    13. Tighten
    Tighten the nut to 5 N·m (44 lb in).

  13. Install the left rear quarter trim. Refer to Rear Quarter Lower Trim Panel Replacement in Interior Trim.
  14. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
  15. Remove the cap or tape from the A/C lines.
  16. Using a lint-free clean, dry cloth, carefully clean the sealing surface of the evaporator lines and the thermal expansion valve.

    17. Object Number: 297228 Size: SH
  17. Lightly coat the new O-ring seal (1) with mineral base 525 viscosity refrigerant oil.

    18. Important: DO NOT allow any of the mineral base 525 viscosity refrigerant oil on the new O-ring seal to enter the refrigerant system.

  18. Carefully slide the new O-ring seal (1) onto the A/C line until seated.

    19. Allow a light coating of the refrigerant oil to remain on the A/C line in the area indicated (2) ONLY.


    Object Number: 400659 Size: SH
  19. Install the A/C line block fitting.
  20. Install the A/C line block fitting bolt.

    21. Tighten
    Tighten the bolt to 20 N·m ( 15 lb ft).

  21. Lower the vehicle.
  22. Evacuate, charge and leak test the system. Refer to Refrigerant Recovery and Recharging