my 96 vette runs very hot in town about 240 and hotter and has no heater. the fan blows nothing but cold air. driving down the highway runs about 185 and stays there and still cold air with the heater on? where do i begin on this journey?  

Gee, we seem to be having a surge in C4 overheating/no heat problems!

My first guess for your car running hot would be the cooling fan sensor isn't working right and not turning the fan on when the motor gets to operating temp. The fact the car cools down when you're driving down the highway supports this theory. If it's not the sensor, then the cooling fan motor must be bad.

As for the no heat, I'd check your heater valve controls/vaccuum lines and make sure they're working properly. Sounds like the heater contorl valve isn't opening up like it should to let hot water into the heater core. Or, a vaccuum line may have gone bad and the valve isn't gettting the vaccuum to function.  

I would also check and make sure you're not leaking antifreeze from the manifold.  I had an issue recently that I was losing antifreeze on a GM motor and the heater wasn't working, the leak was at the intake manifold at the area where it routes it back to the heater core.  Fixed the seal, heater worked again.  It wasn't an obvious leak either, was hidden near the back of the engine.