1992 Buick Park Avenue heater core replacement, how do I AC

I can't give you any illustrations, but fortunately, you car is pretty easy to work on.

You'll first need to drain the coolant. The from the engine compartment, remove the two coolant lines that go into the firewall and into the heater core. They're located on the passenger side and right next to the silver-colored a/c accumulator.

Then from under your dashboard, remove the screws holding the plastic cover over the heater core. Then inside you'll remove the two screw holding the heater core inside of the module.

That's it. Installation is the reverse of removal.