help please, I'm freezing, no heater

Hi:
A couple weeks ago I changed the heater core in my silverado 2001, just found out that hot air is not comming out, I checked the hoses that goes to the heater core and both feel hot, removed the actuator that closes and opens the heater core wall and nothing, also when I turn the ac on I have some leaking inside seems like the drain is stuck or something cold air no problem, blower no problem
Please help, any advise will be highly appreciate.
Marcos

It may be vapor lock? Air might have been trapped in the heater core when you changed it. With water present at both ends it will have a hard time getting out. Start the truck with the radiator open, heater on and see if it "burps?" Try making the front of the truck higher than the core, open the cap and start it the engine to force the air pocket to the cap? Remove a hose and pour coolant into the core?