You could try checking or changing your thermostat and or check to see that there is in fact hot water from your radiator running into your engine and then through your car via 2 rad hoses located on your firewall in the engine compartment, 1 hose going to the heating system and the other hose returning from the heating system. The blower motor or heating systems in most cars have their own little radiator located most of the time just behind the blower motor inside your car. It receives hot water from the engine in order to blow out the hot air that we receive inside the car. If you don't have any hot air then check those things. Be sure to have enough water in your cooling system and that the thermostat is opening when the engine is warm for the hot water to begin circulating through your engine and through your heating system. NEVER OPEN THE RADIATER CAP WHEN THE ENGINE IS HOT! The hot water and pressure will spay out causing burns to your face and skin!