How do you replace the thermostat located on a 1997 Mazda 626 4 cylinder?

To replace the thermostat on a 1997 Mazda 626 with a 4-cylinder engine, first, ensure the engine is cool and disconnect the negative battery cable. Drain the coolant from the radiator, then remove the upper radiator hose connected to the thermostat housing. Unbolt the thermostat housing, take out the old thermostat, and clean the mating surfaces. Install the new thermostat, reassemble the housing and hose, refill the coolant, and reconnect the battery.