front heater is blowing cool air.

Hello, ensure all air pockets are purged from the cooling system. If this is completed, carefully ensure that you have a blistering hot hose going into the heater core, and also check the hose coming out of it for relative temperature. As long there is the same hot temperature going in and out of the heater core, you should also have hot air inside the vehicle. If you do not, you could have a temperature blend door actuator issue, or a problem with the doors in the plenum itself. If temperatures are not hot in and / or out of the heater core, you have another problem under the hood. A heater control valve could be the culprit as well.