The heater core on a Buick vehicle works in conjunction with the engine cooling system to provide hot air to heat the passenger cabin. Heated engine coolant flows from the engine to the heater core located in the heater/air conditioner housing through rubber heater hoses. Air drawn from either outside the vehicle or inside the passenger cabin, is pushed across the heater core by the heater blower fan. This heated air is then distributed through the heater and defroster vents through a series of ducts. The heater core on a Buick will be located in the heater housing, located either in the engine bay on the passenger side of the firewall, or underneath the dash on the passenger side of the cabin. Procedures for removing the heater core in either instance are similar, but you will need to consult the service manual for specific details.
Disconnect the ground cable from the negative battery terminal by loosening the clamp and removing the cable from the battery post.
Remove the radiator cap.
Locate the petcock valve on the lower corner of the radiator. Place a waste oil collection pan underneath the valve and open it to drain the coolant from the cooling system.
Locate the heater hoses. There will be two hoses that run from the engine and connect to the inlet and outlet ports of the heater core that extend through the heater/air conditioner housing on the left side of the engine bay. Disconnect the heater hoses by loosening the hose clamps and pulling the hoses off the inlet and outlet ports.
Remove the chrome trip piece at the base of the windshield, by removing the retaining screws, if equipped.
Remove the debris screen from the cowl (the portion of the vehicle's body just below the windshield) by removing the screws that retain it.
Label and disconnect the electrical leads attached to the blower motor. Remove the blower motor mounting screws and remove the motor from the vehicle.
Remove the retaining screws that secure the cover plate to the heater/air conditioning housing, and remove the cover plate from the vehicle.
Remove the heater core retaining bolt. To remove the heater core by pulling it straight up and out of the housing.
Drop the new heater core into position in the heater/air conditioner housing and reinstall the bolt that retains it.
Apply body sealer to the cover plate and heater/air conditioning housing mating surface, then reinstall the cover plate and the screws that retain it.
Reinstall the blower motor into the heater/air conditioner housing along with the screws that retain it. Reattach the electrical leads for the blower motor.
Reinstall the debris screen in the vehicle's cowl along with the screws that retain it.
Reinstall the chrome trip piece at the base of the windshield along with the screws that retain it.
Reattach the heater hoses to the inlet and outlet ports on the heater core. Reinstall and tighten the hose clamps.
Close the petcock valve on the lower corner of the radiator.
Fill the radiator with a 50/50 mix of antifreeze and water.
Reinstall the radiator cap.
Run the engine and visually inspect for leaks.
Wait until the engine cools, then remove the radiator cap and check the coolant level. Add coolant as necessary.
