How Do You Fix Your Heat In A Pontiac Sunbird 1996

No heat could mean a bad heater core, or a blend door stuck in the AC position. Check if you have coolant going to the heater core - two 1" dia. hoses run from the engine through the firewall to the heater core - do they get warm/hot with the engine running? If not, is your radiator fluid topped off? Any issues with engine coolant flow? Check if your blend door moves by switching back and forth from heat to cool - can you hear it moving? (you don't mention if your blower motor works - does it?) As old as your car is, it can be a number of issues, but those listed above are the easiest to check.