Sounds like the terminals on the gauge are backwards (reversed). It shouldn't move any direction when the switch is turned on and it is cold. It should start moving as the engine warms up, the gauge should go up.
As Hotrod Lincoln said, the same wire that supplies the fuel gauge with battery voltage also feed voltage to the temp gauge.
I would look to see if the gauge is even hooked up, or perhaps only one wire hooked up. The new cluster should have the terminals marked which is for the temp sender (green wire) and which is from the ignition switch for battery voltage.
I recently had to navigate through someone else work and they did not hook up all the wires (new wiring kit) and had to sort through what they had and didn't have to get both the temp and fuel gauge working.
