How hot is hot?

That's hot but not dangerous. Operating temp on my ('90's) BMWs is 108C = 226F...

Dart273 has a good sequence. First make sure your instruments aren't lying to you. I would put the probe in a cup of boiling water (at the elevation of Phoenix, about 210F) and make sure the gauge reading matches.

If the gauge is right, next take the 'stat out and put it in hot water. If it's a 180F unit, it should be fully open well before boiling.

Then if you still hear hoofbeats, start looking for zebras instead of horses. :)
(such as: electric fans hooked up backwards so they're pushing against the incoming air)...