Heater Core: Service and Repair

Heater Core Replacement

Removal Procedure






Important: Do not attempt to open the coolant cap while the cooling system is under pressure.

1. Disconnect the negative battery cable.
2. Remove the coolant cap from the coolant surge tank.

Caution: To avoid any vehicle damage, serious personal injury or death when major components are removed from the vehicle and the vehicle is supported by a hoist, support the vehicle with jack stands at the opposite end from which the components are being removed and strap the vehicle to the hoist.






3. Raise the vehicle.
4. Remove the lower cradle splash shield to cradle and wheelhouse fasteners and remove the splash shield.

Important: Failure to use a drain hose will result in uncontrolled coolant flow direction.

5. Slide a pliable piece of hose with an inside diameter of 3/8 in over the radiator drain tube.






Important: A 7.6 L (8 qt) coolant container will be needed.

6. Route the hose rearward and down to an approved coolant container.

Important: Only open the drain valve 1-2 turns.

7. Use a flat-blade screwdriver or pliers to open the radiator drain valve and drain the coolant.

Approximately 3.5 L (4 qt) of coolant can be drained from the radiator. Additional coolant will remain in some cooling system components. When completely drained, close the coolant drain valve and remove the drain hose.






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.

8. Install the lower cradle splash shield by sliding the shield (1) between the wheelhouse linen (2) and the wheelhouse (3). Install the splash shield to wheelhouse and cradle fasteners.

Tighten
Tighten the splash shield-to-wheelhouse and cradle fasteners to 5 Nm (44 lb in).

9. Lower the vehicle.






10. Remove the heater inlet hose:
- From the auxiliary water pump outlet on L81 engines
- From the thermostat outlet on L61 engines






11. Remove the heater return hose:
- From the head bridge on L81 engines
- From the block inlet on L61 engines
12. Place the end of heater return hose in a container and apply low pressure 34 kPa (5 psi) shop air to the heater inlet hose to blow the coolant out of the heater core.






13. Remove the right console extension.






Caution: Heater core pipes may be hot!

14. Remove the heater core pipe to heater core clamps. The clamps may need to be rotated to gain access to the clamp retaining tab.
15. Gently pull the pipes forward to remove the pipes from the heater core end tank.
16. Place absorbent rags under the heater core pipe joints to catch any residual coolant.






17. Remove the heater core retaining screw and strap.

Important: Use care not to spill any residual coolant on carpet or seats.

Important: The center console forward edge may need to be pulled outward to allow for the core to be removed.

Pull the heater core out of the HVAC module and into the passenger foot area.

Installation Procedure






1. Slide the heater core into the HVAC module being careful not to damage the foam seals.

Tighten
Tighten the heater core retaining strap screw to 1.9 Nm (9 lb in).






2. Install the bushings and O-rings onto the heater core pipes.
3. Install the heater pipes into the core and install the plastic clamps. The heater pipe clamps will only go on one way. The lower clamp hinge fits into the tab of the heater core retaining strap.






4. Install the right console extension.






5. Install the heater inlet hose to recirculation pump on L81, to thermostat outlet on L61.
6. Install the clamp at the 12 o'clock position.






7. Install the heater return hose to the thermostat inlet on L61.
8. Install the clamp at the 12 o'clock position.
9. Install the heater return hose to return inlet fitting on L81.
10. Install the clamp at the 3 o'clock position.
11. Rinse off any coolant that was spilled in the engine compartment.






12. Connect the negative battery cable.

Tighten
Tighten the battery terminal bolts to 17 Nm (13 lb ft).

Important: The vehicle must be level when filling the cooling system.

13. Slowly add a mixture of 50/50 DEX-COOL� antifreeze and clean water to the coolant surge tank until the level reaches the cold indicator, surge tank seam.

Capacity
- Fill the L81 cooling system volumes and heater core to 7.4 L (7.8 qt).
- Fill the L61 cooling system volumes and heater core to 7.0 L (7.4 qt).

14. Start the engine and inspect for cooling system leaks.
15. Run the engine until the thermostat has opened, use Tech 2 to verify the ECT is 87�C (188�F) or greater. Add coolant as necessary to bring the level up to the coolant surge tank cold line.
16. Install the coolant surge tank coolant cap.