How to Change the Heater Core in a 1998 Pontiac Sunfire

The heater in the Pontiac Sunfire makes use of hot engine coolant flowing through the heater core to provide heat inside the cabin of the car. If the heater core is clogged, or begins to leak, you need to replace it. The most common cause of a failed heater core is failing to flush the cooling system periodically to remove sludge buildup. You can complete this procedure yourself, and save a considerable amount of money over taking it to a repair shop. You should set aside an entire day for the project, however, so that you do not feel the need to rush.

Instructions

1

Place a drain pan under the radiator and open the valve on the bottom with a wrench to drain the cooling system. Disconnect the cables from the battery by loosening the terminal nuts with a wrench. Wait a few minutes before doing anything else so that the air bags will not accidently deploy.

2

Place the wheel chocks behind the rear wheels of the Sunfire. Lift the front of the car up with the automobile jack. Place a jack stand under the Pontiac near the jacking point and raise it to the frame. Crawl under the car and disconnect the hoses from the heater core using a screwdriver to loosen the hose clamps.

3

Remove the jack stand from under the car. Lower the Sunfire to the ground. Move to the inside of the car and remove the instrument panel, starting with the defrosting grille. Remove the screws from the end caps using a screwdriver and then pull them off. Remove the trim plate from the instrument cluster using the screwdriver.

4

Remove the heater and air conditioner control panel. Disconnect the air distribution ducts using the screwdriver and pull them out. Disconnect the wiring harness from the instrument panel light. Remove the screws that hold the instrument panel to the tie bar, and pull the instrument panel out.

5

Remove the heater core cover. Remove the heater core from the mounting clamps using a wrench and pull it from the Pontiac. Install the new heater core and clamp it into place. Install the heater core cover. Install the instrument panel and mount it to the tie bar with the screwdriver. Plug the wiring harness into the instrument panel light.

6

Install the air distribution ducts and fasten them in place with the screwdriver. Install the heater and air conditioner control panel. Install the trim plate on the instrument cluster. Install the end caps and then secure them with the screwdriver. Install the defrosting grille and secure it with the screwdriver.

7

Move to the outside of the Sunfire. Raise the Pontiac with the automobile jack. Place a jack stand under the car near the jacking point and raise it to the frame. Crawl under the car and connect the hoses to the heater core. Tighten the hose clamps with the screwdriver. Remove the jack stand from under the Sunfire and lower the vehicle to the ground.

8

Connect the battery cables to the Pontiac and tighten the terminal nuts with the wrench. Refill the radiator and reservoir with fresh engine coolant. Start the Sunfire and check thoroughly for leaking.