Hi Karen,
The thermostat is behind the block where the coolant rail is going into the engine as well.
If you want the check the item you have to do that:
Take it out and put in boiling water.
If the thermostat will not open at the boiling point or before the boiling point (I do not know which kind of part you have),
then you can be sure that the item is broken and has to be changed.
Hope, this will help you.
Adam, April 2008