GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2000 🢒 Montana 🢒 HVAC 🢒 HVAC Systems - Manual 🢒 Auxiliary HVAC Module Replacement

Removal Procedure
  1. Recover the refrigerant. Refer to Refrigerant Recovery and Recharging .
  2. Drain the cooling system. Refer to Cooling System Draining and Filling in Engine Cooling.
  3. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.

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

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

  5. Disconnect the A/C line block fitting, remove and discard the O-ring seals, and cap or tape the lines to prevent contamination of the system.

    6. Object Number: 400657 Size: SH
  6. Disconnect the heater hoses quick disconnects.
  7. Lower the vehicle.
  8. Remove the left side quarter trim. Refer to Rear Quarter Lower Trim Panel Replacement in Interior Trim.

    9. Object Number: 401095 Size: SH
  9. Disconnect the following items at the HVAC module:
    10. • The electrical connectors (1,2)
    • The vacuum line (3)
  10. Disconnect the rear compartment air outlet duct from the HVAC module.
  11. Remove the mounting bolts and the nut from the HVAC module.

    12. Object Number: 400655 Size: SH
  12. Remove the HVAC module.
  13. Remove and discard the HVAC module to body seals.

Installation Procedure
  1. Install new HVAC module to body seals.

    2. Object Number: 400655 Size: SH
  2. Install the HVAC module

    3. 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.

  3. Install the HVAC module mounting bolts and the nut.

    4. Tighten
    Tighten the bolts and the nut to 10 N·m (89 lb in).

  4. Reconnect the rear compartment air outlet duct.

    5. Object Number: 401095 Size: SH
  5. Connect the following items at the heater A/C module:
    6. • The electrical connectors (1,2)
    • The vacuum line (3)
  6. Install the left side quarter trim panel. Refer to Rear Quarter Lower Trim Panel Replacement in Interior Trim.
  7. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.

    8. Object Number: 400657 Size: SH
  8. Connect both of the heater hoses to the pipes.
  9. Remove the cap or tape from the A/C lines.
  10. Using a lint-free clean, dry cloth, carefully clean the sealing surfaces of the A/C lines.

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

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

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

    13. 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
  13. Install the rear A/C line block fitting bolt.

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

  14. Lower the vehicle.
  15. Refill the coolant. Refer to Cooling System Draining and Filling in Engine Cooling.
  16. Evacuate and charge the system. Refer to Refrigerant Recovery and Recharging .
  17. Leak test the A/C system. Refer to Leak Testing .