heat problem

Ok so i have a problem, i have changed the thermostat , flush and filled the coolant, blew out the heater core.but after a week or so i have no heat. The heater core is not leaking into the passenger compartment, the coolant is full. anyone have any idea what the problem could be ?

Welcome to AF!

What year and model GP is this? se, gt, gtp? And does it have the digital climate controll unit?

in addition to answering Tim's (Tblake) questions in case it's HVAC control issues, are both heater core hoses getting as hot as the radiator hoses, or are they luke warm (indicating a heater core blockage)?