1997 Pontiac Grand Am Heater

Just about every Grand Am owner will have to survive the right of passage of replacing the heater core.
The heater core itself is not bad most of the time, the plastic tubes attached to the heater core that poke through holes in the firewall are what fail. The tubes split where they attach on the heater core.

Jack up the car and support it with jack stands.
Find the two hoses that connect to the heater core, about center of the firewall.
A few inches towards the passenger side of the car, and down a little is a nipple poking out of the firewall, this is a drain tube for the heater box. If it’s wet with coolant, you know you heater core needs to be replaced.