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

Removal Procedure
  1. Remove the air cleaner. Refer to Air Cleaner Assembly Replacement
  2. Drain the engine coolant.

    3. Refer to Cooling System Draining and Filling in Engine Cooling.

  3. Remove the heater hoses. Refer to Heater Hoses Replacement in Heater Hose Replacement.
  4. Remove the screws that retain the cover to the heater assembly.
  5. Remove the screws and the straps that retain the heater core to the heater assembly.
  6. Remove the heater core from the vehicle.

Installation Procedure
  1. Install the heater core to the vehicle.

    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 screws and the straps that retain the heater core to the heater assembly.

    3. Tighten
    Tighten the screws and the straps that retain the heater core to the heater assembly to 2 N·m (18 lb in).

  3. Install the screws that retain the cover to the heater assembly.

    4. Tighten
    Tighten the screws that retain the cover to the heater assembly to 2 N·m (18 lb in).

  4. Install the heater hoses. Refer to Heater Hoses Replacement in Heater Hose Replacement.
  5. Fill the cooling system. Refer to Cooling System Draining and Filling in Engine Cooling.
  6. Ensure that no leaks exist in the cooling system.
  7. Install the air cleaner. Refer to Air Cleaner Assembly Replacement