antifreeze leak, no heat

Your heater core needs to be replaced because it is leaking coolant out of it. The heater core is a radiator that brings in hot coolant so the heater fan can blow heated air at you. When the core is leaking it is not properly circulating hot coolant through it, so that coolant is cooler and thus you have no heat. It will not get better or fix itself, you need to get a new heater core, have the dashboard (different for each vehicle) taken apart at least partially, and replaced. Then you need to have your coolant either flushed or at least topped off and bled (to remove air bubbles). Sounds like a pain in the ass? It usually is. Any questions, just ask, and good luck!