2000 Dodge Caravan running hot

The engine cooling system is a closed system. It needs to be this way for many reasons. Mostly so pressure can build and this way it can raise the boiling point of the whole cooling system. You may have a leak, a bad thermostat, or many, more serious problems. It can be pressure tested to pinpoint the leak. I think its best to find a good shop where ASE certified technicians can help you with it. This problem could potentially cause a serious engine mechanical failure. No heat is the first sign something is wrong. It may be just a bad radiator cap, or just need fluid. I hope its not an expensive repair.