no heat

i have a 95 grand prix se with the 3.1 and i have no heat coming out the car is at operating temp but no heat comes out? i replaced the thermostat,water pump and radiator cap i don't what else to chek or to replace? please help

Did you have this problem before you changed all those parts?
Did you bleed the system of air after you replaced them?
Are both hose connected to the heater core getting hot?
Are you losing coolant? If so, is it getting in the oil?

i had no heat before i changed the parts and yes i bleed the lines and no iam not losing coolant and i can't tell if the heater core lines are getting circulation.