How do you go about replacing the heater core on a 2003 Grand Prix?

Answer by  wickjeff (105)

Replacing the heater core on any vehicle can become time consuming and patience testing. After removing the passenger carpet and possibly part of the dashpad, the heater core may be accessed and the in/out fittings disconnected. Next, the mounting bolts must be removed in order to take the heater core out of its recepticle. Installion is in reverse, needs bled.

Answer by  doc325 (454)

The heater core can be accessed from under the passender side dash board. Remove the air ducts and shields to get to the core. Remove and replace the core and replace the shields.

Answer by  JohnHolmes (2660)

The heater core will be located behind the glove box area. You can get to it from under the hood by removing the four retaining bolts. Once removed install the new one and bolt up the system.