GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2004 🢒 TopKick C-Series (Crew) C4/C5 🢒 HVAC 🢒 Heating, Ventilation and Air Conditioning 🢒 Air Conditioning (A/C) Evaporator and Blower Module Assembly Replacement

Tools Required

J 39400-A Halogen Leak Detector

Removal Procedure
  1. Recover the refrigerant from the A/C system. Refer to Refrigerant Recovery and Recharging .
  2. Remove the right wheelhouse panel. Refer to Wheelhouse Panel Replacement in Body Front End.
  3. Remove the air cleaner layer. Refer to the appropriate procedure:
    4. •  Air Cleaner Replacement in Engine Controls-6.6L.
    •  Air Cleaner Replacement in Engine Controls-8.1L.
    •  Air Cleaner Replacement in Engine Controls-7.8L.
    • Caterpillar® 3126 Unit Repair Manual
  4. Disconnect the low pressure sensor electrical connector.
  5. Disconnect the blower motor assembly electrical connector.
  6. Disconnect the blower motor resistor assembly electrical connector.
  7. Remove the multi-use module bracket. Refer to the appropriate procedure:
    8. •  Multiuse Module Bracket Replacement in Engine Controls-6.6L.
    •  Multiuse Module Bracket Replacement in Engine Controls-8.1L.
    •  Multiuse Module Bracket Replacement in Engine Controls-7.8L.
    • Caterpillar® 3126 Unit Repair Manual

    Object Number: 769765 Size: SH
  8. Remove the evaporator outlet hose retaining nut (5) from the accumulator.

    9. Object Number: 769799 Size: SH
  9. Remove the compressor inlet hose retaining nut (2).
  10. Disconnect the low pressure sensor electrical connector.

    11. Object Number: 769756 Size: SH
  11. Remove the retaining nuts (3) from the accumulator retaining bracket.
  12. Remove the accumulator (5) from the bracket.
  13. Remove the O-ring seals.

    14. Object Number: 800358 Size: SH
  14. Remove the retaining nut (3) from the evaporator inlet tube (5).
  15. Remove the evaporator inlet tube from the evaporator.
  16. Remove the O-ring seal.

    17. Object Number: 769765 Size: SH
  17. Remove the retaining nut (4) from the evaporator outlet tube (3).
  18. Remove the evaporator outlet tube from the evaporator.
  19. Remove the O-ring seal.

    20. Object Number: 300824 Size: SH
  20. Remove the evaporator and blower module assembly (3).

Installation Procedure

    Object Number: 300824 Size: SH
  1. Install the evaporator and blower module assembly (3).

    2. 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 evaporator and blower module assembly retaining nuts (2) .

    3. Tighten
    Tighten the nuts to 6 N·m (53 lb in).

  3. Install new O-ring seals to the evaporator inlet and outlet tubes. Refer to O-Ring Replacement .

    4. Object Number: 800358 Size: SH
  4. Install the evaporator inlet tube (4) to the evaporator.
  5. Install the evaporator inlet tube retaining nut.

    6. Tighten
    Tighten the nut to 18 N·m (13 lb ft).


    Object Number: 769765 Size: SH
  6. Install the evaporator outlet tube (3) to the evaporator.
  7. Install the evaporator outlet tube retaining nut.

    8. Tighten
    Tighten the nut to 18 N·m (13 lb ft).


    Object Number: 769756 Size: SH
  8. Install the accumulator (5) to the bracket.
  9. Install the nuts (3) to the accumulator retaining bracket

    10. Tighten
    Tighten the nuts to 9 N·m (80 lb in).

  10. Connect the low pressure sensor electrical connector.
  11. Install new O-ring seals. Refer to O-Ring Replacement .
  12. Install the evaporator outlet hose.
  13. Install the evaporator outlet hose retaining nut (5) to the accumulator.

    14. Tighten
    Tighten the nut to 18 N·m (13 lb ft).

  14. Install the compressor inlet hose.

    15. Object Number: 769799 Size: SH
  15. Install the compressor inlet hose retaining nut (2) to the accumulator.

    16. Tighten
    Tighten the nut to 18 N·m (13 lb ft).

  16. Install the multi-use module bracket. Refer to the appropriate procedure:
    17. •  Multiuse Module Bracket Replacement in Engine Controls-6.6L.
    •  Multiuse Module Bracket Replacement in Engine Controls-8.1L.
    •  Multiuse Module Bracket Replacement in Engine Controls-7.8L.
    • Caterpillar® 3126 Unit Repair Manual
  17. Connect the low pressure sensor electrical connector.
  18. Connect the blower motor assembly electrical connector.
  19. Connect the blower motor resistor assembly electrical connector.
  20. Install the air cleaner layer. Refer to the appropriate procedure:
    21. •  Air Cleaner Replacement in Engine Controls-6.6L.
    •  Air Cleaner Replacement in Engine Controls-8.1L.
    •  Air Cleaner Replacement in Engine Controls-7.8L.
    • Caterpillar® 3126 Unit Repair Manual
  21. Install the right wheelhouse panel. Refer to Wheelhouse Panel Replacement in Body Front End.
  22. Evacuate and recharge the A/C system. Refer to Refrigerant Recovery and Recharging .
  23. Leak test the fittings of the components using the J 39400-A .