GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1999 🢒 Safari - 2WD 🢒 Engine 🢒 Engine Cooling 🢒 Auxiliary Heater Core Replacement

Removal Procedure
  1. Remove the air cleaner. Refer to Air Cleaner Assembly Replacement in Engine Controls.
  2. Drain the engine coolant. Refer to Cooling System Draining and Filling in Engine Cooling.
  3. Remove the body side front lower trim panel. Refer to Body Side Front Lower Trim Panel Replacement in Interior Trim.
  4. Remove the clamps from the auxiliary heater pipes.
  5. Disconnect the auxiliary heater pipes from the auxiliary heater module.
  6. Remove the screws and the band clamp from the right side of the heater core.
  7. Remove the screw and the band clamp from the left side of the heater core.

    8. Important: Before removing the auxiliary heater module from the vehicle, be sure to place a protective cover on the floor in order to prevent coolant from leaking onto the carpet.

  8. Remove the heater core from the heater core case.

    9. Object Number: 280250 Size: SH
  9. Remove the seals from the heater core.

Installation Procedure

    Object Number: 280250 Size: SH
  1. Install the seals to the heater core.
  2. Install the heater core into the heater core case.

    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 screw and the band clamp to the left side of the heater core.

    4. Tighten
    Tighten the screws and the band clamp to the left side of the heater core to 2 N·m (18 lb in).

  4. Install the screws and the band clamp to the right side of the heater core.

    5. Tighten
    Tighten the screw and the band clamp to the right side of the heater core to 2 N·m (18 lb in).

  5. Connect the auxiliary heater pipes from the auxiliary heater module.
  6. Install the clamps to the auxiliary heater pipes.
  7. Install the body side front lower trim panel. Refer to Body Side Front Lower Trim Panel Replacement in Interior Trim.
  8. Fill the system with engine coolant. Refer to Cooling System Draining and Filling in Engine Cooling.
  9. Inspect the system for leaks.
  10. Install the air cleaner. Refer to Air Cleaner Assembly Replacement in Engine Controls.