General Steps (Highly Simplified and Incomplete):
1. Preparation: Disconnect the battery negative terminal. Drain the coolant system completely. Gather all necessary tools, including various sockets, wrenches, screwdrivers (Phillips and flathead), possibly a plastic trim removal tool, and possibly a coolant flush kit. You'll also need a new heater core and potentially new O-rings and seals. Have plenty of shop towels or rags ready.
2. Dashboard Disassembly: This is the most time-consuming and delicate part. You will likely need to remove various parts of the dashboard, including the glove box, radio, and possibly the instrument panel. This often involves removing screws, clips, and connectors. Carefully label and photograph each step to ensure proper reassembly. Consult your repair manual for the exact procedure.
3. Heater Core Access: Once the dashboard is partially or fully disassembled, you'll gain access to the heater core, usually located behind the dashboard. Its location varies slightly depending on the exact model year and trim level of your Grand Am. Your repair manual will be crucial here.
4. Heater Core Removal: Carefully disconnect the heater core hoses. Be prepared for some coolant spillage. Remove the heater core from its housing. Note the orientation of the core and the location of any clips or brackets.
5. Heater Core Installation: Install the new heater core, ensuring it's properly seated and oriented. Reconnect the hoses.
6. Dashboard Reassembly: Carefully reassemble the dashboard, paying close attention to the order and position of all parts. Reconnect all electrical connectors.
7. Coolant Refill and Bleed: Refill the coolant system with the proper type and amount of coolant. Bleed the system to remove any air pockets. Run the engine and check for leaks.
Critical Considerations:
* Repair Manual: You absolutely must have a repair manual specific to your 1991 Pontiac Grand Am. This manual will provide detailed instructions, diagrams, and torque specifications.
* Patience and Precision: This is a time-consuming and detailed job requiring patience and precision.
* Safety: Wear safety glasses to protect your eyes from coolant.
* Professional Help: If you are not comfortable with complex automotive repairs, strongly consider taking your vehicle to a qualified mechanic. The cost of professional repair will likely be less than the potential damage caused by an improper repair.
This is a highly simplified overview. Attempting this repair without the proper knowledge, tools, and repair manual could lead to significant damage to your vehicle. Consult a repair manual and/or a qualified mechanic before proceeding.
