GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2008 🢒 CTS 🢒 HVAC 🢒 Heating, Ventilation, and Air Conditioning 🢒 HVAC Module Assembly Replacement

Tools Required
    • J 39400-A Halogen Leak Detector
    • J 38185 Hose Clamp Pliers
    • J 45689 A/C Quick Joint Tool

Removal Procedure
  1. Recover the refrigerant. Refer to Refrigerant Recovery and Recharging.
  2. Remove the battery. Refer to Battery Replacement.
  3. Drain the coolant. Refer to Cooling System Draining and Filling.

    4. Object Number: 760782 Size: SH
  4. Using the J 38185 disconnect the heater inlet hose (1).

    5. Object Number: 760784 Size: SH
  5. Using the J 38185 disconnect the heater outlet hose (1).
  6. Disconnect both A/C lines at the cowl.

    7. Important: The body of the tool should be parallel to the A/C line.


    Object Number: 817526 Size: SH
  7. Using the J 45689  (1) insert the probe end into the two small openings of the plastic quick joint.
  8. Remove both quick joint clamps.
  9. Disconnect both A/C lines.

    10. Object Number: 756222 Size: SH
  10. Remove the IP Carrier. Refer to Instrument Panel Carrier Replacement.
  11. Remove the air inlet assembly.
  12. Disconnect the HVAC module electrical connector.
  13. Disconnect the HVAC module drain tube (2) from the floor.

    14. Object Number: 756217 Size: SH
  14. Press the tab and release the left rear duct from the HVAC module.

    15. Object Number: 756233 Size: SH
  15. Disconnect the left rear heater duct from the HVAC module.

    16. Object Number: 756215 Size: SH
  16. Press the tab and release the right rear duct from the HVAC module.

    17. Object Number: 756234 Size: SH
  17. Disconnect the right rear heater ducts from the HVAC module.

    18. Object Number: 756232 Size: SH
  18. Remove the lower left HVAC module mounting nut (1).

    19. Object Number: 756237 Size: SH
  19. Remove the upper left HVAC module mounting nut (1).
  20. Remove the HVAC module from the vehicle.

    21. Object Number: 817511 Size: SH
  21. Remove the foam from the A/C lines.
  22. Remove the foam from around the heater pipes.

Installation Procedure

    Object Number: 819805 Size: SH
  1. Install the thick foam packing (1) on the heater core pipes.
  2. Install the thin foam packing (2) on the heater core pipes.

    3. Object Number: 819804 Size: SH
  3. Install the thick foam packing (1) on the A/C lines.
  4. Install the thin foam packing (2) on the A/C lines.
  5. Install the HVAC module into the vehicle.

    6. Notice: Refer to Fastener Notice in the Preface section.

  6. Install the upper left HVAC module mounting nut (1).

    7. Tighten
    Tighten the nut to 9 N·m (80 lb in).


    Object Number: 756232 Size: SH
  7. Install the lower left HVAC module mounting nut (1).

    8. Tighten
    Tighten the nut to 9 N·m (80 lb in).

  8. Connect the rear heater ducts to the HVAC module.
  9. Connect the drain tube to the bottom of the HVAC module.

    10. Object Number: 756222 Size: SH
  10. Connect the drain tube (2) to the floor.
  11. Connect the HVAC electrical connector.
  12. Install the air inlet assembly.

    13. Object Number: 817518 Size: SH
  13. Lubricate the O-rings of the A/C line with refrigerant oil before connecting the A/C lines. Refer to O-Ring Replacement.

    14. Object Number: 817539 Size: SH
  14. Install the A/C line and A/C line quick connect line clamp (1) to the evaporator.

    15. Object Number: 817519 Size: SH

    Important: Press the A/C line quick connect line clamp together until you hear it engage.

  15. Engage the clamp.

    16. Object Number: 817540 Size: SH
  16. Install the A/C line and A/C line quick connect line clamp (1) to the evaporator.

    17. Object Number: 817519 Size: SH

    Important: Press the A/C line quick connect line clamp together until you hear it engage.

  17. Engage the clamp.

    18. Object Number: 760782 Size: SH
  18. Connect the heater inlet hose (1) using J 38185 .

    19. Object Number: 760784 Size: SH
  19. Connect the heater outlet hose (1) using J 38185 .
  20. Install the IP carrier. Refer to Instrument Panel Carrier Replacement.
  21. Install the battery. Refer to Battery Replacement.
  22. Fill the coolant. Refer to Cooling System Draining and Filling.
  23. Evacuate and recharge the AC system. Refer to Refrigerant Recovery and Recharging.
  24. Leak test the fittings of the component using J 39400-A .