1994 Pontiac Grand Am Part location

You didn't say what engine you have.
Generally the thermostat housing is where the upper radiator hose connects to the engine.

If you have a V6 the waterpump is on the front of the engine and is driven by a fan belt just like any other engine for the last 100 years. If you have a 4 cylinder the waterpump is driven by a rotating shaft driven by the timing chain.