Visible light is reflected from outside, heat is radiated from within. All an invisible cloak has to do is change the way light flows around you, but you can't stop being warm unless you're dead, and thermodynamics says that heat has to go somewhere. A cooling system with a large heat sink might provide temporary thermal invisibility, assuming it doesn't leak, but it's not going to be very stealthy-- like walking around with a refrigerator on your back.
Originally Posted by Sharlos
STARGAZING: All I see are the lights of a billion places I'll never go. --Howard Tayler, Schlock Mercenary