2000/dodge grand caravan sport..the heater is throwing hot air even if temp control is on cold and the vent selector is on fresh air vent...whats wrong with it..??

Maybe nothing. The temperature control does nothing unless the heat or A/C is on and it's just pulling warm air in from outside with fresh air set and not recirculate. Now if you mean with A/C turned on different story. The A/C is not working.

From http://www.dodge.com/en/owners/manuals/ The Front Blower Control selects whether the Climate Control System is ON or OFF. When the blower control is set to the O (OFF) position the front blower will turn off and the system will be placed in the Recirculation mode. When the blower control is set to any position other than off, it selects the amount of air delivered to the passenger compartment. The top right button with the snowflake thing must be lit to have cold air. . click for full screen